[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-28 Thread LLVM Continuous Integration via cfe-commits 

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder 
`openmp-offload-libc-amdgpu-runtime` running on `omp-vega20-1` while building 
`clang` at step 7 "Add check check-offload".

Full details are available at: 
https://lab.llvm.org/buildbot/#/builders/73/builds/12566


Here is the relevant piece of the build log for the reference

```
Step 7 (Add check check-offload) failure: test (failure)
 TEST 'libomptarget :: amdgcn-amd-amdhsa :: 
mapping/declare_mapper_nested_mappers.cpp' FAILED 
Exit Code: 2

Command Output (stdout):
--
# RUN: at line 1
/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/./bin/clang++
 -fopenmp-I 
/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.src/offload/test 
-I 
/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/openmp/runtime/src
 -L 
/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/offload
 -L /home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/./lib -L 
/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/openmp/runtime/src
  -nogpulib 
-Wl,-rpath,/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/offload
 
-Wl,-rpath,/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/openmp/runtime/src
 
-Wl,-rpath,/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/./lib
  -fopenmp-targets=amdgcn-amd-amdhsa 
/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.src/offload/test/mapping/declare_mapper_nested_mappers.cpp
 -o 
/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/offload/test/amdgcn-amd-amdhsa/mapping/Output/declare_mapper_nested_mappers.cpp.tmp
 -Xoffload-linker -lc -Xoffload-linker -lm 
/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/./lib/libomptarget.devicertl.a
 && 
/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/offload/test/amdgcn-amd-amdhsa/mapping/Output/declare_mapper_nested_mappers.cpp.tmp
 | 
/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/./bin/FileCheck
 
/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.src/offload/test/mapping/declare_mapper_nested_mappers.cpp
# executed command: 
/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/./bin/clang++
 -fopenmp -I 
/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.src/offload/test 
-I 
/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/openmp/runtime/src
 -L 
/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/offload
 -L /home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/./lib -L 
/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/openmp/runtime/src
 -nogpulib 
-Wl,-rpath,/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/offload
 
-Wl,-rpath,/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/openmp/runtime/src
 
-Wl,-rpath,/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/./lib
 -fopenmp-targets=amdgcn-amd-amdhsa 
/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.src/offload/test/mapping/declare_mapper_nested_mappers.cpp
 -o 
/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/offload/test/amdgcn-amd-amdhsa/mapping/Output/declare_mapper_nested_mappers.cpp.tmp
 -Xoffload-linker -lc -Xoffload-linker -lm 
/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/./lib/libomptarget.devicertl.a
# executed command: 
/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/offload/test/amdgcn-amd-amdhsa/mapping/Output/declare_mapper_nested_mappers.cpp.tmp
# note: command had no output on stdout or stderr
# error: command failed with exit status: -11
# executed command: 
/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/./bin/FileCheck
 
/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.src/offload/test/mapping/declare_mapper_nested_mappers.cpp
# .---command stderr
# | FileCheck error: '' is empty.
# | FileCheck command line:  
/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/./bin/FileCheck
 
/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.src/offload/test/mapping/declare_mapper_nested_mappers.cpp
# `-
# error: command failed with exit status: 2

--




```



https://github.com/llvm/llvm-project/pull/122486
___
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-28 Thread Nikita Popov via cfe-commits 

https://github.com/nikic closed https://github.com/llvm/llvm-project/pull/122486
___
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-27 Thread Aaron Ballman via cfe-commits 

https://github.com/AaronBallman approved this pull request.

LGTM!

https://github.com/llvm/llvm-project/pull/122486
___
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-27 Thread Nikita Popov via cfe-commits 

https://github.com/nikic updated 
https://github.com/llvm/llvm-project/pull/122486

>From 925f74cad21eb6c46514d1ae543ac202073baf27 Mon Sep 17 00:00:00 2001
From: Nikita Popov 
Date: Fri, 10 Jan 2025 17:01:07 +0100
Subject: [PATCH 1/5] [Clang] Add -fwrapv-pointer flag

GCC supports three flags related to overflow behavior:
 * `-fwrapv`: Makes signed integer overflow well-defined.
 * `-fwrapv-pointer`: Makes pointer overflow well-defined.
 * `-fno-strict-overflow`: Implies `-fwrapv -fwrapv-pointer`,
   making both signed integer overflow and pointer overflow
   well-defined.

Clang currently only supports `-fno-strict-overflow` and `-fwrapv`,
but not `-fwrapv-pointer`.

This PR proposes to introduce `-fwrapv-pointer` and adjust the
semantics of `-fwrapv` to match GCC.

This allows signed integer overflow and pointer overflow to be
controlled independently, while `-fno-strict-overflow` still
exists to control both at the same time (and that option is
consistent across GCC and Clang).
---
 clang/docs/ReleaseNotes.rst   | 15 ++-
 clang/include/clang/Basic/LangOptions.def |  1 +
 clang/include/clang/Driver/Options.td |  5 
 clang/lib/CodeGen/CGBuiltin.cpp   |  2 +-
 clang/lib/CodeGen/CGExpr.cpp  | 27 +--
 clang/lib/CodeGen/CGExprScalar.cpp| 12 -
 clang/lib/Driver/SanitizerArgs.cpp|  3 +++
 clang/lib/Driver/ToolChains/CommonArgs.cpp| 15 ---
 clang/lib/Frontend/CompilerInvocation.cpp |  4 +++
 clang/lib/Sema/SemaExpr.cpp   |  2 +-
 clang/test/CodeGen/integer-overflow.c | 13 ++---
 clang/test/CodeGen/pointer-overflow.c | 12 +
 clang/test/Driver/clang_wrapv_opts.c  | 15 ++-
 .../Sema/tautological-pointer-comparison.c|  2 +-
 14 files changed, 88 insertions(+), 40 deletions(-)
 create mode 100644 clang/test/CodeGen/pointer-overflow.c

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index cad17c1b3957b6..12b2893b1eb824 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -79,7 +79,15 @@ code bases.
   Undefined behavior due to pointer addition overflow can be reliably detected
   using ``-fsanitize=pointer-overflow``. It is also possible to use
   ``-fno-strict-overflow`` to opt-in to a language dialect where signed integer
-  and pointer overflow are well-defined.
+  and pointer overflow are well-defined. Since Clang 20, it is also possible
+  to use ``-fwrapv-pointer`` to only make pointer overflow well-defined, while
+  not affecting the behavior of signed integer overflow.
+
+- The ``-fwrapv`` flag now only makes signed integer overflow well-defined,
+  without affecting pointer overflow, which is controlled by a new
+  ``-fwrapv-pointer`` flag. The ``-fno-strict-overflow`` flag now implies
+  both ``-fwrapv`` and ``-fwrapv-pointer`` and as such retains its old meaning.
+  The new behavior matches GCC.
 
 C/C++ Language Potentially Breaking Changes
 ---
@@ -500,6 +508,11 @@ New Compiler Flags
 - clang-cl and clang-dxc now support 
``-fdiagnostics-color=[auto|never|always]``
   in addition to ``-f[no-]color-diagnostics``.
 
+- The new ``-fwrapv-pointer`` flag opts-in to a language dialect where pointer
+  overflow is well-defined. The ``-fwrapv`` flag previously implied
+  ``-fwrapv-pointer`` as well, but no longer does. ``-fno-strict-overflow``
+  implies ``-fwrapv -fwrapv-pointer``. The flags now match GCC.
+
 Deprecated Compiler Flags
 -
 
diff --git a/clang/include/clang/Basic/LangOptions.def 
b/clang/include/clang/Basic/LangOptions.def
index a980be853d53e6..1bcec212fd332e 100644
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -407,6 +407,7 @@ VALUE_LANGOPT(TrivialAutoVarInitMaxSize, 32, 0,
  "stop trivial automatic variable initialization if var size 
exceeds the specified size (in bytes). Must be greater than 0.")
 ENUM_LANGOPT(SignedOverflowBehavior, SignedOverflowBehaviorTy, 2, 
SOB_Undefined,
  "signed integer overflow handling")
+LANGOPT(PointerOverflowDefined, 1, 0, "make pointer overflow defined")
 ENUM_LANGOPT(ThreadModel  , ThreadModelKind, 2, ThreadModelKind::POSIX, 
"Thread Model")
 
 BENIGN_LANGOPT(ArrowDepth, 32, 256,
diff --git a/clang/include/clang/Driver/Options.td 
b/clang/include/clang/Driver/Options.td
index 852051e772fc1c..820ed088029f8c 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -4299,6 +4299,11 @@ def fwrapv : Flag<["-"], "fwrapv">, Group,
   HelpText<"Treat signed integer overflow as two's complement">;
 def fno_wrapv : Flag<["-"], "fno-wrapv">, Group,
   Visibility<[ClangOption, CLOption, FlangOption]>;
+def fwrapv_pointer : Flag<["-"], "fwrapv-pointer">, Group,
+  Visibility<[ClangOption, CLOption, CC1Option, FlangOption, FC1Option]>,
+  HelpText<"Treat p

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-25 Thread Fangrui Song via cfe-commits 


@@ -1,11 +1,20 @@
 // RUN: %clang -### -S -fwrapv -fno-wrapv -fwrapv %s 2>&1 | FileCheck 
-check-prefix=CHECK1 %s
 // CHECK1: -fwrapv
 //
+// RUN: %clang -### -S -fwrapv-pointer -fno-wrapv-pointer -fwrapv-pointer %s 
2>&1 | FileCheck -check-prefix=CHECK1-POINTER %s
+// CHECK1-POINTER: -fwrapv-pointer
+//
 // RUN: %clang -### -S -fstrict-overflow -fno-strict-overflow %s 2>&1 | 
FileCheck -check-prefix=CHECK2 %s
-// CHECK2: -fwrapv
+// CHECK2: -fwrapv{{.*}}-fwrapv-pointer
 //
-// RUN: %clang -### -S -fwrapv -fstrict-overflow %s 2>&1 | FileCheck 
-check-prefix=CHECK3 %s
+// RUN: %clang -### -S -fwrapv -fstrict-overflow %s 2>&1 | FileCheck 
-check-prefix=CHECK3 %s --implicit-check-not="-fwrapv-pointer"
 // CHECK3: -fwrapv
 //
-// RUN: %clang -### -S -fno-wrapv -fno-strict-overflow %s 2>&1 | FileCheck 
-check-prefix=CHECK4 %s
-// CHECK4-NOT: -fwrapv
+// RUN: %clang -### -S -fwrapv-pointer -fstrict-overflow %s 2>&1 | FileCheck 
-check-prefix=CHECK3-POINTER %s --implicit-check-not="-fwrapv"
+// CHECK3-POINTER: -fwrapv-pointer
+//
+// RUN: %clang -### -S -fno-wrapv -fno-strict-overflow %s 2>&1 | FileCheck 
-check-prefix=CHECK4 %s --implicit-check-not="-fwrapv"
+// CHECK4: -fwrapv-pointer
+//
+// RUN: %clang -### -S -fno-wrapv-pointer -fno-strict-overflow %s 2>&1 | 
FileCheck -check-prefix=CHECK4-POINTER %s --implicit-check-not="-fwrapv-pointer"
+// CHECK4-POINTER: -fwrapv

MaskRay wrote:

You might need `"-fwrapv"`. Otherwise, IIUC even if the output is 
`-fwrap-pointer`, the check will pass. Because `-fwrapv` matches, and the 
remaining string will pass the --implicit-check-not check.

https://github.com/llvm/llvm-project/pull/122486
___
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-25 Thread Fangrui Song via cfe-commits 


@@ -1,11 +1,20 @@
 // RUN: %clang -### -S -fwrapv -fno-wrapv -fwrapv %s 2>&1 | FileCheck 
-check-prefix=CHECK1 %s
 // CHECK1: -fwrapv
 //
+// RUN: %clang -### -S -fwrapv-pointer -fno-wrapv-pointer -fwrapv-pointer %s 
2>&1 | FileCheck -check-prefix=CHECK1-POINTER %s
+// CHECK1-POINTER: -fwrapv-pointer
+//
 // RUN: %clang -### -S -fstrict-overflow -fno-strict-overflow %s 2>&1 | 
FileCheck -check-prefix=CHECK2 %s
-// CHECK2: -fwrapv
+// CHECK2: -fwrapv{{.*}}-fwrapv-pointer
 //
-// RUN: %clang -### -S -fwrapv -fstrict-overflow %s 2>&1 | FileCheck 
-check-prefix=CHECK3 %s
+// RUN: %clang -### -S -fwrapv -fstrict-overflow %s 2>&1 | FileCheck 
-check-prefix=CHECK3 %s --implicit-check-not="-fwrapv-pointer"

MaskRay wrote:

When testing both -fno-strict-overflow and -fwrapv{-pointer}, perhaps add 
-Werror to ensure that we don't emit a unused option warning (which would 
happen if the Driver code forgot to claim an option).

https://github.com/llvm/llvm-project/pull/122486
___
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-25 Thread Fangrui Song via cfe-commits 

https://github.com/MaskRay edited 
https://github.com/llvm/llvm-project/pull/122486
___
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-25 Thread Fangrui Song via cfe-commits 

https://github.com/MaskRay approved this pull request.

Will be used by chromium and other users. There is some gap in sanitizer that 
is not so important.

LGTM, but other reviewers need to stamp as well.

https://github.com/llvm/llvm-project/pull/122486
___
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-24 Thread Eli Friedman via cfe-commits 


@@ -4311,14 +4311,14 @@ LValue CodeGenFunction::EmitArraySubscriptExpr(const 
ArraySubscriptExpr *E,
 // GEP indexes are signed, and scaling an index isn't permitted to
 // signed-overflow, so we use the same semantics for our explicit
 // multiply.  We suppress this if overflow is not undefined behavior.
-if (getLangOpts().isSignedOverflowDefined()) {
+if (getLangOpts().PointerOverflowDefined) {
   Idx = Builder.CreateMul(Idx, numElements);

efriedma-quic wrote:

Opened #124358 .

https://github.com/llvm/llvm-project/pull/122486
___
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-24 Thread Eli Friedman via cfe-commits 


@@ -4311,14 +4311,14 @@ LValue CodeGenFunction::EmitArraySubscriptExpr(const 
ArraySubscriptExpr *E,
 // GEP indexes are signed, and scaling an index isn't permitted to
 // signed-overflow, so we use the same semantics for our explicit
 // multiply.  We suppress this if overflow is not undefined behavior.
-if (getLangOpts().isSignedOverflowDefined()) {
+if (getLangOpts().PointerOverflowDefined) {
   Idx = Builder.CreateMul(Idx, numElements);

efriedma-quic wrote:

This looks like a gap in the pointer-overflow sanitizer: we should trigger the 
sanitizer if the multiply overflows.  Same issue pops up in a few other places. 
 But you don't need to fix this in this patch, I guess.

https://github.com/llvm/llvm-project/pull/122486
___
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-24 Thread Eli Friedman via cfe-commits 

https://github.com/efriedma-quic edited 
https://github.com/llvm/llvm-project/pull/122486
___
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-24 Thread Eli Friedman via cfe-commits 

https://github.com/efriedma-quic commented:

CC @llvm/clang-vendors : this changes the behavior of -fwrapv.

Internally, I expect it's going to be a bit painful to communicate to all our 
internal teams that they need to change their -fwrapv usage to 
-fno-strict-overflow, but if we think it's important to align with gcc in that 
respect, we can do it, I guess?

-

The implementation looks correct.

https://github.com/llvm/llvm-project/pull/122486
___
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-24 Thread Nikita Popov via cfe-commits 


@@ -1,11 +1,24 @@
 // RUN: %clang -### -S -fwrapv -fno-wrapv -fwrapv %s 2>&1 | FileCheck 
-check-prefix=CHECK1 %s
 // CHECK1: -fwrapv
 //
+// RUN: %clang -### -S -fwrapv-pointer -fno-wrapv-pointer -fwrapv-pointer %s 
2>&1 | FileCheck -check-prefix=CHECK1-POINTER %s
+// CHECK1-POINTER: -fwrapv-pointer
+//
 // RUN: %clang -### -S -fstrict-overflow -fno-strict-overflow %s 2>&1 | 
FileCheck -check-prefix=CHECK2 %s
-// CHECK2: -fwrapv
+// CHECK2: -fwrapv{{.*}}-fwrapv-pointer
 //
 // RUN: %clang -### -S -fwrapv -fstrict-overflow %s 2>&1 | FileCheck 
-check-prefix=CHECK3 %s
 // CHECK3: -fwrapv
 //
+// RUN: %clang -### -S -fwrapv-pointer -fstrict-overflow %s 2>&1 | FileCheck 
-check-prefix=CHECK3-POINTER %s
+// CHECK3-POINTER: -fwrapv-pointer

nikic wrote:

Good idea, I've switched the last four tests to use `--implicit-check-not`.

https://github.com/llvm/llvm-project/pull/122486
___
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-24 Thread Nikita Popov via cfe-commits 

https://github.com/nikic updated 
https://github.com/llvm/llvm-project/pull/122486

>From 925f74cad21eb6c46514d1ae543ac202073baf27 Mon Sep 17 00:00:00 2001
From: Nikita Popov 
Date: Fri, 10 Jan 2025 17:01:07 +0100
Subject: [PATCH 1/3] [Clang] Add -fwrapv-pointer flag

GCC supports three flags related to overflow behavior:
 * `-fwrapv`: Makes signed integer overflow well-defined.
 * `-fwrapv-pointer`: Makes pointer overflow well-defined.
 * `-fno-strict-overflow`: Implies `-fwrapv -fwrapv-pointer`,
   making both signed integer overflow and pointer overflow
   well-defined.

Clang currently only supports `-fno-strict-overflow` and `-fwrapv`,
but not `-fwrapv-pointer`.

This PR proposes to introduce `-fwrapv-pointer` and adjust the
semantics of `-fwrapv` to match GCC.

This allows signed integer overflow and pointer overflow to be
controlled independently, while `-fno-strict-overflow` still
exists to control both at the same time (and that option is
consistent across GCC and Clang).
---
 clang/docs/ReleaseNotes.rst   | 15 ++-
 clang/include/clang/Basic/LangOptions.def |  1 +
 clang/include/clang/Driver/Options.td |  5 
 clang/lib/CodeGen/CGBuiltin.cpp   |  2 +-
 clang/lib/CodeGen/CGExpr.cpp  | 27 +--
 clang/lib/CodeGen/CGExprScalar.cpp| 12 -
 clang/lib/Driver/SanitizerArgs.cpp|  3 +++
 clang/lib/Driver/ToolChains/CommonArgs.cpp| 15 ---
 clang/lib/Frontend/CompilerInvocation.cpp |  4 +++
 clang/lib/Sema/SemaExpr.cpp   |  2 +-
 clang/test/CodeGen/integer-overflow.c | 13 ++---
 clang/test/CodeGen/pointer-overflow.c | 12 +
 clang/test/Driver/clang_wrapv_opts.c  | 15 ++-
 .../Sema/tautological-pointer-comparison.c|  2 +-
 14 files changed, 88 insertions(+), 40 deletions(-)
 create mode 100644 clang/test/CodeGen/pointer-overflow.c

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index cad17c1b3957b6..12b2893b1eb824 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -79,7 +79,15 @@ code bases.
   Undefined behavior due to pointer addition overflow can be reliably detected
   using ``-fsanitize=pointer-overflow``. It is also possible to use
   ``-fno-strict-overflow`` to opt-in to a language dialect where signed integer
-  and pointer overflow are well-defined.
+  and pointer overflow are well-defined. Since Clang 20, it is also possible
+  to use ``-fwrapv-pointer`` to only make pointer overflow well-defined, while
+  not affecting the behavior of signed integer overflow.
+
+- The ``-fwrapv`` flag now only makes signed integer overflow well-defined,
+  without affecting pointer overflow, which is controlled by a new
+  ``-fwrapv-pointer`` flag. The ``-fno-strict-overflow`` flag now implies
+  both ``-fwrapv`` and ``-fwrapv-pointer`` and as such retains its old meaning.
+  The new behavior matches GCC.
 
 C/C++ Language Potentially Breaking Changes
 ---
@@ -500,6 +508,11 @@ New Compiler Flags
 - clang-cl and clang-dxc now support 
``-fdiagnostics-color=[auto|never|always]``
   in addition to ``-f[no-]color-diagnostics``.
 
+- The new ``-fwrapv-pointer`` flag opts-in to a language dialect where pointer
+  overflow is well-defined. The ``-fwrapv`` flag previously implied
+  ``-fwrapv-pointer`` as well, but no longer does. ``-fno-strict-overflow``
+  implies ``-fwrapv -fwrapv-pointer``. The flags now match GCC.
+
 Deprecated Compiler Flags
 -
 
diff --git a/clang/include/clang/Basic/LangOptions.def 
b/clang/include/clang/Basic/LangOptions.def
index a980be853d53e6..1bcec212fd332e 100644
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -407,6 +407,7 @@ VALUE_LANGOPT(TrivialAutoVarInitMaxSize, 32, 0,
  "stop trivial automatic variable initialization if var size 
exceeds the specified size (in bytes). Must be greater than 0.")
 ENUM_LANGOPT(SignedOverflowBehavior, SignedOverflowBehaviorTy, 2, 
SOB_Undefined,
  "signed integer overflow handling")
+LANGOPT(PointerOverflowDefined, 1, 0, "make pointer overflow defined")
 ENUM_LANGOPT(ThreadModel  , ThreadModelKind, 2, ThreadModelKind::POSIX, 
"Thread Model")
 
 BENIGN_LANGOPT(ArrowDepth, 32, 256,
diff --git a/clang/include/clang/Driver/Options.td 
b/clang/include/clang/Driver/Options.td
index 852051e772fc1c..820ed088029f8c 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -4299,6 +4299,11 @@ def fwrapv : Flag<["-"], "fwrapv">, Group,
   HelpText<"Treat signed integer overflow as two's complement">;
 def fno_wrapv : Flag<["-"], "fno-wrapv">, Group,
   Visibility<[ClangOption, CLOption, FlangOption]>;
+def fwrapv_pointer : Flag<["-"], "fwrapv-pointer">, Group,
+  Visibility<[ClangOption, CLOption, CC1Option, FlangOption, FC1Option]>,
+  HelpText<"Treat p

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-24 Thread Fangrui Song via cfe-commits 


@@ -1,11 +1,24 @@
 // RUN: %clang -### -S -fwrapv -fno-wrapv -fwrapv %s 2>&1 | FileCheck 
-check-prefix=CHECK1 %s
 // CHECK1: -fwrapv
 //
+// RUN: %clang -### -S -fwrapv-pointer -fno-wrapv-pointer -fwrapv-pointer %s 
2>&1 | FileCheck -check-prefix=CHECK1-POINTER %s
+// CHECK1-POINTER: -fwrapv-pointer
+//
 // RUN: %clang -### -S -fstrict-overflow -fno-strict-overflow %s 2>&1 | 
FileCheck -check-prefix=CHECK2 %s
-// CHECK2: -fwrapv
+// CHECK2: -fwrapv{{.*}}-fwrapv-pointer
 //
 // RUN: %clang -### -S -fwrapv -fstrict-overflow %s 2>&1 | FileCheck 
-check-prefix=CHECK3 %s
 // CHECK3: -fwrapv
 //
+// RUN: %clang -### -S -fwrapv-pointer -fstrict-overflow %s 2>&1 | FileCheck 
-check-prefix=CHECK3-POINTER %s
+// CHECK3-POINTER: -fwrapv-pointer

MaskRay wrote:

Needs a NOT pattern for -fwrapv.

Perhaps use --implicit-check-not=-fwrap so that we don't need a NOT before and 
a NOT after the positive pattern.

https://github.com/llvm/llvm-project/pull/122486
___
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-24 Thread Nikita Popov via cfe-commits 


@@ -57,15 +57,6 @@ void test1(void) {
   // TRAPV_HANDLER: foo(
   --a;
   
-  // -fwrapv should turn off inbounds for GEP's, PR9256
-  extern int* P;
-  ++P;
-  // DEFAULT: getelementptr inbounds nuw i32, ptr
-  // WRAPV: getelementptr i32, ptr
-  // TRAPV: getelementptr inbounds nuw i32, ptr
-  // CATCH_UB_POINTER: getelementptr inbounds nuw i32, ptr
-  // NOCATCH_UB_POINTER: getelementptr i32, ptr

nikic wrote:

I've restored the test. The intent here was to split off the pointer case into 
pointer-overflow.c, but there's no reason we can't have both...

https://github.com/llvm/llvm-project/pull/122486
___
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-24 Thread Nikita Popov via cfe-commits 

https://github.com/nikic updated 
https://github.com/llvm/llvm-project/pull/122486

>From 925f74cad21eb6c46514d1ae543ac202073baf27 Mon Sep 17 00:00:00 2001
From: Nikita Popov 
Date: Fri, 10 Jan 2025 17:01:07 +0100
Subject: [PATCH 1/2] [Clang] Add -fwrapv-pointer flag

GCC supports three flags related to overflow behavior:
 * `-fwrapv`: Makes signed integer overflow well-defined.
 * `-fwrapv-pointer`: Makes pointer overflow well-defined.
 * `-fno-strict-overflow`: Implies `-fwrapv -fwrapv-pointer`,
   making both signed integer overflow and pointer overflow
   well-defined.

Clang currently only supports `-fno-strict-overflow` and `-fwrapv`,
but not `-fwrapv-pointer`.

This PR proposes to introduce `-fwrapv-pointer` and adjust the
semantics of `-fwrapv` to match GCC.

This allows signed integer overflow and pointer overflow to be
controlled independently, while `-fno-strict-overflow` still
exists to control both at the same time (and that option is
consistent across GCC and Clang).
---
 clang/docs/ReleaseNotes.rst   | 15 ++-
 clang/include/clang/Basic/LangOptions.def |  1 +
 clang/include/clang/Driver/Options.td |  5 
 clang/lib/CodeGen/CGBuiltin.cpp   |  2 +-
 clang/lib/CodeGen/CGExpr.cpp  | 27 +--
 clang/lib/CodeGen/CGExprScalar.cpp| 12 -
 clang/lib/Driver/SanitizerArgs.cpp|  3 +++
 clang/lib/Driver/ToolChains/CommonArgs.cpp| 15 ---
 clang/lib/Frontend/CompilerInvocation.cpp |  4 +++
 clang/lib/Sema/SemaExpr.cpp   |  2 +-
 clang/test/CodeGen/integer-overflow.c | 13 ++---
 clang/test/CodeGen/pointer-overflow.c | 12 +
 clang/test/Driver/clang_wrapv_opts.c  | 15 ++-
 .../Sema/tautological-pointer-comparison.c|  2 +-
 14 files changed, 88 insertions(+), 40 deletions(-)
 create mode 100644 clang/test/CodeGen/pointer-overflow.c

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index cad17c1b3957b6..12b2893b1eb824 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -79,7 +79,15 @@ code bases.
   Undefined behavior due to pointer addition overflow can be reliably detected
   using ``-fsanitize=pointer-overflow``. It is also possible to use
   ``-fno-strict-overflow`` to opt-in to a language dialect where signed integer
-  and pointer overflow are well-defined.
+  and pointer overflow are well-defined. Since Clang 20, it is also possible
+  to use ``-fwrapv-pointer`` to only make pointer overflow well-defined, while
+  not affecting the behavior of signed integer overflow.
+
+- The ``-fwrapv`` flag now only makes signed integer overflow well-defined,
+  without affecting pointer overflow, which is controlled by a new
+  ``-fwrapv-pointer`` flag. The ``-fno-strict-overflow`` flag now implies
+  both ``-fwrapv`` and ``-fwrapv-pointer`` and as such retains its old meaning.
+  The new behavior matches GCC.
 
 C/C++ Language Potentially Breaking Changes
 ---
@@ -500,6 +508,11 @@ New Compiler Flags
 - clang-cl and clang-dxc now support 
``-fdiagnostics-color=[auto|never|always]``
   in addition to ``-f[no-]color-diagnostics``.
 
+- The new ``-fwrapv-pointer`` flag opts-in to a language dialect where pointer
+  overflow is well-defined. The ``-fwrapv`` flag previously implied
+  ``-fwrapv-pointer`` as well, but no longer does. ``-fno-strict-overflow``
+  implies ``-fwrapv -fwrapv-pointer``. The flags now match GCC.
+
 Deprecated Compiler Flags
 -
 
diff --git a/clang/include/clang/Basic/LangOptions.def 
b/clang/include/clang/Basic/LangOptions.def
index a980be853d53e6..1bcec212fd332e 100644
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -407,6 +407,7 @@ VALUE_LANGOPT(TrivialAutoVarInitMaxSize, 32, 0,
  "stop trivial automatic variable initialization if var size 
exceeds the specified size (in bytes). Must be greater than 0.")
 ENUM_LANGOPT(SignedOverflowBehavior, SignedOverflowBehaviorTy, 2, 
SOB_Undefined,
  "signed integer overflow handling")
+LANGOPT(PointerOverflowDefined, 1, 0, "make pointer overflow defined")
 ENUM_LANGOPT(ThreadModel  , ThreadModelKind, 2, ThreadModelKind::POSIX, 
"Thread Model")
 
 BENIGN_LANGOPT(ArrowDepth, 32, 256,
diff --git a/clang/include/clang/Driver/Options.td 
b/clang/include/clang/Driver/Options.td
index 852051e772fc1c..820ed088029f8c 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -4299,6 +4299,11 @@ def fwrapv : Flag<["-"], "fwrapv">, Group,
   HelpText<"Treat signed integer overflow as two's complement">;
 def fno_wrapv : Flag<["-"], "fno-wrapv">, Group,
   Visibility<[ClangOption, CLOption, FlangOption]>;
+def fwrapv_pointer : Flag<["-"], "fwrapv-pointer">, Group,
+  Visibility<[ClangOption, CLOption, CC1Option, FlangOption, FC1Option]>,
+  HelpText<"Treat p

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-24 Thread Nikita Popov via cfe-commits 

https://github.com/nikic updated 
https://github.com/llvm/llvm-project/pull/122486

>From 925f74cad21eb6c46514d1ae543ac202073baf27 Mon Sep 17 00:00:00 2001
From: Nikita Popov 
Date: Fri, 10 Jan 2025 17:01:07 +0100
Subject: [PATCH 1/2] [Clang] Add -fwrapv-pointer flag

GCC supports three flags related to overflow behavior:
 * `-fwrapv`: Makes signed integer overflow well-defined.
 * `-fwrapv-pointer`: Makes pointer overflow well-defined.
 * `-fno-strict-overflow`: Implies `-fwrapv -fwrapv-pointer`,
   making both signed integer overflow and pointer overflow
   well-defined.

Clang currently only supports `-fno-strict-overflow` and `-fwrapv`,
but not `-fwrapv-pointer`.

This PR proposes to introduce `-fwrapv-pointer` and adjust the
semantics of `-fwrapv` to match GCC.

This allows signed integer overflow and pointer overflow to be
controlled independently, while `-fno-strict-overflow` still
exists to control both at the same time (and that option is
consistent across GCC and Clang).
---
 clang/docs/ReleaseNotes.rst   | 15 ++-
 clang/include/clang/Basic/LangOptions.def |  1 +
 clang/include/clang/Driver/Options.td |  5 
 clang/lib/CodeGen/CGBuiltin.cpp   |  2 +-
 clang/lib/CodeGen/CGExpr.cpp  | 27 +--
 clang/lib/CodeGen/CGExprScalar.cpp| 12 -
 clang/lib/Driver/SanitizerArgs.cpp|  3 +++
 clang/lib/Driver/ToolChains/CommonArgs.cpp| 15 ---
 clang/lib/Frontend/CompilerInvocation.cpp |  4 +++
 clang/lib/Sema/SemaExpr.cpp   |  2 +-
 clang/test/CodeGen/integer-overflow.c | 13 ++---
 clang/test/CodeGen/pointer-overflow.c | 12 +
 clang/test/Driver/clang_wrapv_opts.c  | 15 ++-
 .../Sema/tautological-pointer-comparison.c|  2 +-
 14 files changed, 88 insertions(+), 40 deletions(-)
 create mode 100644 clang/test/CodeGen/pointer-overflow.c

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index cad17c1b3957b6..12b2893b1eb824 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -79,7 +79,15 @@ code bases.
   Undefined behavior due to pointer addition overflow can be reliably detected
   using ``-fsanitize=pointer-overflow``. It is also possible to use
   ``-fno-strict-overflow`` to opt-in to a language dialect where signed integer
-  and pointer overflow are well-defined.
+  and pointer overflow are well-defined. Since Clang 20, it is also possible
+  to use ``-fwrapv-pointer`` to only make pointer overflow well-defined, while
+  not affecting the behavior of signed integer overflow.
+
+- The ``-fwrapv`` flag now only makes signed integer overflow well-defined,
+  without affecting pointer overflow, which is controlled by a new
+  ``-fwrapv-pointer`` flag. The ``-fno-strict-overflow`` flag now implies
+  both ``-fwrapv`` and ``-fwrapv-pointer`` and as such retains its old meaning.
+  The new behavior matches GCC.
 
 C/C++ Language Potentially Breaking Changes
 ---
@@ -500,6 +508,11 @@ New Compiler Flags
 - clang-cl and clang-dxc now support 
``-fdiagnostics-color=[auto|never|always]``
   in addition to ``-f[no-]color-diagnostics``.
 
+- The new ``-fwrapv-pointer`` flag opts-in to a language dialect where pointer
+  overflow is well-defined. The ``-fwrapv`` flag previously implied
+  ``-fwrapv-pointer`` as well, but no longer does. ``-fno-strict-overflow``
+  implies ``-fwrapv -fwrapv-pointer``. The flags now match GCC.
+
 Deprecated Compiler Flags
 -
 
diff --git a/clang/include/clang/Basic/LangOptions.def 
b/clang/include/clang/Basic/LangOptions.def
index a980be853d53e6..1bcec212fd332e 100644
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -407,6 +407,7 @@ VALUE_LANGOPT(TrivialAutoVarInitMaxSize, 32, 0,
  "stop trivial automatic variable initialization if var size 
exceeds the specified size (in bytes). Must be greater than 0.")
 ENUM_LANGOPT(SignedOverflowBehavior, SignedOverflowBehaviorTy, 2, 
SOB_Undefined,
  "signed integer overflow handling")
+LANGOPT(PointerOverflowDefined, 1, 0, "make pointer overflow defined")
 ENUM_LANGOPT(ThreadModel  , ThreadModelKind, 2, ThreadModelKind::POSIX, 
"Thread Model")
 
 BENIGN_LANGOPT(ArrowDepth, 32, 256,
diff --git a/clang/include/clang/Driver/Options.td 
b/clang/include/clang/Driver/Options.td
index 852051e772fc1c..820ed088029f8c 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -4299,6 +4299,11 @@ def fwrapv : Flag<["-"], "fwrapv">, Group,
   HelpText<"Treat signed integer overflow as two's complement">;
 def fno_wrapv : Flag<["-"], "fno-wrapv">, Group,
   Visibility<[ClangOption, CLOption, FlangOption]>;
+def fwrapv_pointer : Flag<["-"], "fwrapv-pointer">, Group,
+  Visibility<[ClangOption, CLOption, CC1Option, FlangOption, FC1Option]>,
+  HelpText<"Treat p

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-24 Thread Aaron Ballman via cfe-commits 


@@ -79,7 +79,15 @@ code bases.
   Undefined behavior due to pointer addition overflow can be reliably detected
   using ``-fsanitize=pointer-overflow``. It is also possible to use
   ``-fno-strict-overflow`` to opt-in to a language dialect where signed integer
-  and pointer overflow are well-defined.
+  and pointer overflow are well-defined. Since Clang 20, it is also possible
+  to use ``-fwrapv-pointer`` to only make pointer overflow well-defined, while
+  not affecting the behavior of signed integer overflow.
+
+- The ``-fwrapv`` flag now only makes signed integer overflow well-defined,

AaronBallman wrote:

Curiously enough, we only ever documented the signed integer overflow behavior, 
not the pointer overflow: 
https://clang.llvm.org/docs/ClangCommandLineReference.html#cmdoption-clang-fwrapv

https://github.com/llvm/llvm-project/pull/122486
___
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-24 Thread Aaron Ballman via cfe-commits 


@@ -57,15 +57,6 @@ void test1(void) {
   // TRAPV_HANDLER: foo(
   --a;
   
-  // -fwrapv should turn off inbounds for GEP's, PR9256
-  extern int* P;
-  ++P;
-  // DEFAULT: getelementptr inbounds nuw i32, ptr
-  // WRAPV: getelementptr i32, ptr
-  // TRAPV: getelementptr inbounds nuw i32, ptr
-  // CATCH_UB_POINTER: getelementptr inbounds nuw i32, ptr
-  // NOCATCH_UB_POINTER: getelementptr i32, ptr

AaronBallman wrote:

Should we keep the test but update the comment + expected results?

https://github.com/llvm/llvm-project/pull/122486
___
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-24 Thread Aaron Ballman via cfe-commits 

https://github.com/AaronBallman edited 
https://github.com/llvm/llvm-project/pull/122486
___
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-24 Thread Aaron Ballman via cfe-commits 

https://github.com/AaronBallman commented:

The changes look correct to me, but I'd love to hear from the codegen and 
sanitizer experts as to whether they agree with the changes and the timeline to 
land it for 20.

https://github.com/llvm/llvm-project/pull/122486
___
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-24 Thread Aaron Ballman via cfe-commits 

AaronBallman wrote:

I am a bit concerned about the behavioral change, but given the more aggressive 
optimizations in LLVM 20, I think it makes sense to get this into Clang 20 to 
see what the fallout is during early RCs. If there's negative impact, we can 
consider cherry-picking a revert from the branch. Matching GCC's behavior for 
the options seems like a defensible approach.

https://github.com/llvm/llvm-project/pull/122486
___
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-24 Thread Nikita Popov via cfe-commits 

nikic wrote:

If we want to make this change, I think doing it for Clang 20 would be ideal, 
because it is related to the pointer overflow optimization changes in that 
release.

https://github.com/llvm/llvm-project/pull/122486
___
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-23 Thread Shafik Yaghmour via cfe-commits 

https://github.com/shafik commented:

I feel like matching gcc's behavior makes sense for users but I am not sure 
about the timing for clang-20. This seems like the change in behavior could be 
impactful.

https://github.com/llvm/llvm-project/pull/122486
___
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-23 Thread Carlo Cabrera via cfe-commits 

carlocab wrote:

> Matching gcc's behavior for -f flags both compilers have also makes sense, 
> IMHO.

Agree with this, FWIW.

https://github.com/llvm/llvm-project/pull/122486
___
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-23 Thread Nikita Popov via cfe-commits 

https://github.com/nikic updated 
https://github.com/llvm/llvm-project/pull/122486

>From 925f74cad21eb6c46514d1ae543ac202073baf27 Mon Sep 17 00:00:00 2001
From: Nikita Popov 
Date: Fri, 10 Jan 2025 17:01:07 +0100
Subject: [PATCH] [Clang] Add -fwrapv-pointer flag

GCC supports three flags related to overflow behavior:
 * `-fwrapv`: Makes signed integer overflow well-defined.
 * `-fwrapv-pointer`: Makes pointer overflow well-defined.
 * `-fno-strict-overflow`: Implies `-fwrapv -fwrapv-pointer`,
   making both signed integer overflow and pointer overflow
   well-defined.

Clang currently only supports `-fno-strict-overflow` and `-fwrapv`,
but not `-fwrapv-pointer`.

This PR proposes to introduce `-fwrapv-pointer` and adjust the
semantics of `-fwrapv` to match GCC.

This allows signed integer overflow and pointer overflow to be
controlled independently, while `-fno-strict-overflow` still
exists to control both at the same time (and that option is
consistent across GCC and Clang).
---
 clang/docs/ReleaseNotes.rst   | 15 ++-
 clang/include/clang/Basic/LangOptions.def |  1 +
 clang/include/clang/Driver/Options.td |  5 
 clang/lib/CodeGen/CGBuiltin.cpp   |  2 +-
 clang/lib/CodeGen/CGExpr.cpp  | 27 +--
 clang/lib/CodeGen/CGExprScalar.cpp| 12 -
 clang/lib/Driver/SanitizerArgs.cpp|  3 +++
 clang/lib/Driver/ToolChains/CommonArgs.cpp| 15 ---
 clang/lib/Frontend/CompilerInvocation.cpp |  4 +++
 clang/lib/Sema/SemaExpr.cpp   |  2 +-
 clang/test/CodeGen/integer-overflow.c | 13 ++---
 clang/test/CodeGen/pointer-overflow.c | 12 +
 clang/test/Driver/clang_wrapv_opts.c  | 15 ++-
 .../Sema/tautological-pointer-comparison.c|  2 +-
 14 files changed, 88 insertions(+), 40 deletions(-)
 create mode 100644 clang/test/CodeGen/pointer-overflow.c

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index cad17c1b3957b6..12b2893b1eb824 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -79,7 +79,15 @@ code bases.
   Undefined behavior due to pointer addition overflow can be reliably detected
   using ``-fsanitize=pointer-overflow``. It is also possible to use
   ``-fno-strict-overflow`` to opt-in to a language dialect where signed integer
-  and pointer overflow are well-defined.
+  and pointer overflow are well-defined. Since Clang 20, it is also possible
+  to use ``-fwrapv-pointer`` to only make pointer overflow well-defined, while
+  not affecting the behavior of signed integer overflow.
+
+- The ``-fwrapv`` flag now only makes signed integer overflow well-defined,
+  without affecting pointer overflow, which is controlled by a new
+  ``-fwrapv-pointer`` flag. The ``-fno-strict-overflow`` flag now implies
+  both ``-fwrapv`` and ``-fwrapv-pointer`` and as such retains its old meaning.
+  The new behavior matches GCC.
 
 C/C++ Language Potentially Breaking Changes
 ---
@@ -500,6 +508,11 @@ New Compiler Flags
 - clang-cl and clang-dxc now support 
``-fdiagnostics-color=[auto|never|always]``
   in addition to ``-f[no-]color-diagnostics``.
 
+- The new ``-fwrapv-pointer`` flag opts-in to a language dialect where pointer
+  overflow is well-defined. The ``-fwrapv`` flag previously implied
+  ``-fwrapv-pointer`` as well, but no longer does. ``-fno-strict-overflow``
+  implies ``-fwrapv -fwrapv-pointer``. The flags now match GCC.
+
 Deprecated Compiler Flags
 -
 
diff --git a/clang/include/clang/Basic/LangOptions.def 
b/clang/include/clang/Basic/LangOptions.def
index a980be853d53e6..1bcec212fd332e 100644
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -407,6 +407,7 @@ VALUE_LANGOPT(TrivialAutoVarInitMaxSize, 32, 0,
  "stop trivial automatic variable initialization if var size 
exceeds the specified size (in bytes). Must be greater than 0.")
 ENUM_LANGOPT(SignedOverflowBehavior, SignedOverflowBehaviorTy, 2, 
SOB_Undefined,
  "signed integer overflow handling")
+LANGOPT(PointerOverflowDefined, 1, 0, "make pointer overflow defined")
 ENUM_LANGOPT(ThreadModel  , ThreadModelKind, 2, ThreadModelKind::POSIX, 
"Thread Model")
 
 BENIGN_LANGOPT(ArrowDepth, 32, 256,
diff --git a/clang/include/clang/Driver/Options.td 
b/clang/include/clang/Driver/Options.td
index 852051e772fc1c..820ed088029f8c 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -4299,6 +4299,11 @@ def fwrapv : Flag<["-"], "fwrapv">, Group,
   HelpText<"Treat signed integer overflow as two's complement">;
 def fno_wrapv : Flag<["-"], "fno-wrapv">, Group,
   Visibility<[ClangOption, CLOption, FlangOption]>;
+def fwrapv_pointer : Flag<["-"], "fwrapv-pointer">, Group,
+  Visibility<[ClangOption, CLOption, CC1Option, FlangOption, FC1Option]>,
+  HelpText<"Treat point

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-22 Thread Nico Weber via cfe-commits 

nico wrote:

We (chromium) turned on fwrapv due to the pointer changes, and it had a bit of 
a perf hit. We'd probably switch to this, hoping it'd address the perf issues 
at least some.

Matching gcc's behavior for -f flags both compilers have also makes sense, IMHO.

https://github.com/llvm/llvm-project/pull/122486
___
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-13 Thread Nikita Popov via cfe-commits 

nikic wrote:

> I'm tempted to say we should just treat 
> -fwrapv/-fwrapv-pointer/-fno-strict-overflow as aliases for each other. I 
> don't think anyone using -fwrapv is going to be happy that we're turning on 
> overflow optimizations.

Yeah, I'm not entirely sure this change is worthwhile either. My general 
thinking here was that we already have the `-fno-strict-overflow` flag, which 
works the same on GCC and Clang and disables all overflow optimization. If 
someone wants to disable pointer overflow optimization and they're using 
`-fwrapv` to do that, their code is already broken on GCC. So given that we 
already have an option that works the same for all compilers and compiler 
versions, it's best to go for consistency for the rest.

https://github.com/llvm/llvm-project/pull/122486
___
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-10 Thread Eli Friedman via cfe-commits 

efriedma-quic wrote:

I'm tempted to say we should just treat 
-fwrapv/-fwrapv-pointer/-fno-strict-overflow as aliases for each other.  I 
don't think anyone using -fwrapv is going to be happy that we're turning on 
overflow optimizations.

https://github.com/llvm/llvm-project/pull/122486
___
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-10 Thread Nikita Popov via cfe-commits 

https://github.com/nikic updated 
https://github.com/llvm/llvm-project/pull/122486

>From b32e3e1eee4b359ae2f0a1563420104de8d52277 Mon Sep 17 00:00:00 2001
From: Nikita Popov 
Date: Fri, 10 Jan 2025 17:01:07 +0100
Subject: [PATCH] [Clang] Add -fwrapv-pointer flag

GCC supports three flags related to overflow behavior:
 * `-fwrapv`: Makes signed integer overflow well-defined.
 * `-fwrapv-pointer`: Makes pointer overflow well-defined.
 * `-fno-strict-overflow`: Implies `-fwrapv -fwrapv-pointer`,
   making both signed integer overflow and pointer overflow
   well-defined.

Clang currently only supports `-fno-strict-overflow` and `-fwrapv`,
but not `-fwrapv-pointer`.

This PR proposes to introduce `-fwrapv-pointer` and adjust the
semantics of `-fwrapv` to match GCC.

This allows signed integer overflow and pointer overflow to be
controlled independently, while `-fno-strict-overflow` still
exists to control both at the same time (and that option is
consistent across GCC and Clang).
---
 clang/docs/ReleaseNotes.rst   | 11 
 clang/include/clang/Basic/LangOptions.def |  1 +
 clang/include/clang/Driver/Options.td |  5 
 clang/lib/CodeGen/CGBuiltin.cpp   |  2 +-
 clang/lib/CodeGen/CGExpr.cpp  | 27 +--
 clang/lib/CodeGen/CGExprScalar.cpp| 12 -
 clang/lib/Driver/SanitizerArgs.cpp|  3 +++
 clang/lib/Driver/ToolChains/CommonArgs.cpp| 15 ---
 clang/lib/Frontend/CompilerInvocation.cpp |  4 +++
 clang/lib/Sema/SemaExpr.cpp   |  2 +-
 clang/test/CodeGen/integer-overflow.c | 13 ++---
 clang/test/CodeGen/pointer-overflow.c | 12 +
 clang/test/Driver/clang_wrapv_opts.c  | 15 ++-
 .../Sema/tautological-pointer-comparison.c|  2 +-
 14 files changed, 85 insertions(+), 39 deletions(-)
 create mode 100644 clang/test/CodeGen/pointer-overflow.c

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 511a28c5554bbb..44d98d98411d12 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -58,6 +58,12 @@ code bases.
   containing strict-aliasing violations. The new default behavior can be
   disabled using ``-fno-pointer-tbaa``.
 
+- The ``-fwrapv`` flag now only makes signed integer overflow well-defined,
+  without affecting pointer overflow, which is controlled by a new
+  ``-fwrapv-pointer`` flag. The ``-fno-strict-overflow`` flag now implies
+  both ``-fwrapv`` and ``-fwrapv-pointer`` and as such retains its old meaning.
+  The new behavior matches GCC.
+
 C/C++ Language Potentially Breaking Changes
 ---
 
@@ -464,6 +470,11 @@ New Compiler Flags
 - clang-cl and clang-dxc now support 
``-fdiagnostics-color=[auto|never|always]``
   in addition to ``-f[no-]color-diagnostics``.
 
+- The new ``-fwrapv-pointer`` flag opts-in to a language dialect where pointer
+  overflow is well-defined. The ``-fwrapv`` flag previously implied
+  ``-fwrapv-pointer`` as well, but no longer does. ``-fno-strict-overflow``
+  implies ``-fwrapv -fwrapv-pointer``. The flags now match GCC.
+
 Deprecated Compiler Flags
 -
 
diff --git a/clang/include/clang/Basic/LangOptions.def 
b/clang/include/clang/Basic/LangOptions.def
index 3b833240e5b68c..c4c53d7455c417 100644
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -407,6 +407,7 @@ VALUE_LANGOPT(TrivialAutoVarInitMaxSize, 32, 0,
  "stop trivial automatic variable initialization if var size 
exceeds the specified size (in bytes). Must be greater than 0.")
 ENUM_LANGOPT(SignedOverflowBehavior, SignedOverflowBehaviorTy, 2, 
SOB_Undefined,
  "signed integer overflow handling")
+LANGOPT(PointerOverflowDefined, 1, 0, "make pointer overflow defined")
 ENUM_LANGOPT(ThreadModel  , ThreadModelKind, 2, ThreadModelKind::POSIX, 
"Thread Model")
 
 BENIGN_LANGOPT(ArrowDepth, 32, 256,
diff --git a/clang/include/clang/Driver/Options.td 
b/clang/include/clang/Driver/Options.td
index 41a7e8c3728066..8b45aa6dd4c2df 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -4291,6 +4291,11 @@ def fwrapv : Flag<["-"], "fwrapv">, Group,
   HelpText<"Treat signed integer overflow as two's complement">;
 def fno_wrapv : Flag<["-"], "fno-wrapv">, Group,
   Visibility<[ClangOption, CLOption, FlangOption]>;
+def fwrapv_pointer : Flag<["-"], "fwrapv-pointer">, Group,
+  Visibility<[ClangOption, CLOption, CC1Option, FlangOption, FC1Option]>,
+  HelpText<"Treat pointer overflow as two's complement">;
+def fno_wrapv_pointer : Flag<["-"], "fno-wrapv-pointer">, Group,
+  Visibility<[ClangOption, CLOption, FlangOption]>;
 def fwritable_strings : Flag<["-"], "fwritable-strings">, Group,
   Visibility<[ClangOption, CC1Option]>,
   HelpText<"Store string literals as writable data">,
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/C

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-10 Thread Nikita Popov via cfe-commits 

https://github.com/nikic updated 
https://github.com/llvm/llvm-project/pull/122486

>From 1f3737d2eeb7681cb57a66f7bd6c4614cd038aac Mon Sep 17 00:00:00 2001
From: Nikita Popov 
Date: Fri, 10 Jan 2025 17:01:07 +0100
Subject: [PATCH] [Clang] Add -fwrapv-pointer flag

GCC supports three flags related to overflow behavior:
 * `-fwrapv`: Makes signed integer overflow well-defined.
 * `-fwrapv-pointer`: Makes pointer overflow well-defined.
 * `-fno-strict-overflow`: Implies `-fwrapv -fwrapv-pointer`,
   making both signed integer overflow and pointer overflow
   well-defined.

Clang currently only supports `-fno-strict-overflow` and `-fwrapv`,
but not `-fwrapv-pointer`.

This PR proposes to introduce `-fwrapv-pointer` and adjust the
semantics of `-fwrapv` to match GCC.

This allows signed integer overflow and pointer overflow to be
controlled independently, while `-fno-strict-overflow` still
exists to control both at the same time (and that option is
consistent across GCC and Clang).
---
 clang/docs/ReleaseNotes.rst   | 11 ++
 clang/include/clang/Basic/LangOptions.def |  1 +
 clang/include/clang/Driver/Options.td |  5 +
 clang/lib/CodeGen/CGBuiltin.cpp   |  2 +-
 clang/lib/CodeGen/CGExpr.cpp  | 22 +--
 clang/lib/CodeGen/CGExprScalar.cpp| 12 +-
 clang/lib/Driver/SanitizerArgs.cpp|  3 +++
 clang/lib/Driver/ToolChains/CommonArgs.cpp| 15 +
 clang/lib/Frontend/CompilerInvocation.cpp |  4 
 clang/lib/Sema/SemaExpr.cpp   |  2 +-
 clang/test/CodeGen/integer-overflow.c | 13 ++-
 clang/test/CodeGen/pointer-overflow.c | 12 ++
 clang/test/Driver/clang_wrapv_opts.c  | 15 -
 .../Sema/tautological-pointer-comparison.c|  2 +-
 14 files changed, 83 insertions(+), 36 deletions(-)
 create mode 100644 clang/test/CodeGen/pointer-overflow.c

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 511a28c5554bbb..44d98d98411d12 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -58,6 +58,12 @@ code bases.
   containing strict-aliasing violations. The new default behavior can be
   disabled using ``-fno-pointer-tbaa``.
 
+- The ``-fwrapv`` flag now only makes signed integer overflow well-defined,
+  without affecting pointer overflow, which is controlled by a new
+  ``-fwrapv-pointer`` flag. The ``-fno-strict-overflow`` flag now implies
+  both ``-fwrapv`` and ``-fwrapv-pointer`` and as such retains its old meaning.
+  The new behavior matches GCC.
+
 C/C++ Language Potentially Breaking Changes
 ---
 
@@ -464,6 +470,11 @@ New Compiler Flags
 - clang-cl and clang-dxc now support 
``-fdiagnostics-color=[auto|never|always]``
   in addition to ``-f[no-]color-diagnostics``.
 
+- The new ``-fwrapv-pointer`` flag opts-in to a language dialect where pointer
+  overflow is well-defined. The ``-fwrapv`` flag previously implied
+  ``-fwrapv-pointer`` as well, but no longer does. ``-fno-strict-overflow``
+  implies ``-fwrapv -fwrapv-pointer``. The flags now match GCC.
+
 Deprecated Compiler Flags
 -
 
diff --git a/clang/include/clang/Basic/LangOptions.def 
b/clang/include/clang/Basic/LangOptions.def
index 3b833240e5b68c..c4c53d7455c417 100644
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -407,6 +407,7 @@ VALUE_LANGOPT(TrivialAutoVarInitMaxSize, 32, 0,
  "stop trivial automatic variable initialization if var size 
exceeds the specified size (in bytes). Must be greater than 0.")
 ENUM_LANGOPT(SignedOverflowBehavior, SignedOverflowBehaviorTy, 2, 
SOB_Undefined,
  "signed integer overflow handling")
+LANGOPT(PointerOverflowDefined, 1, 0, "make pointer overflow defined")
 ENUM_LANGOPT(ThreadModel  , ThreadModelKind, 2, ThreadModelKind::POSIX, 
"Thread Model")
 
 BENIGN_LANGOPT(ArrowDepth, 32, 256,
diff --git a/clang/include/clang/Driver/Options.td 
b/clang/include/clang/Driver/Options.td
index 41a7e8c3728066..8b45aa6dd4c2df 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -4291,6 +4291,11 @@ def fwrapv : Flag<["-"], "fwrapv">, Group,
   HelpText<"Treat signed integer overflow as two's complement">;
 def fno_wrapv : Flag<["-"], "fno-wrapv">, Group,
   Visibility<[ClangOption, CLOption, FlangOption]>;
+def fwrapv_pointer : Flag<["-"], "fwrapv-pointer">, Group,
+  Visibility<[ClangOption, CLOption, CC1Option, FlangOption, FC1Option]>,
+  HelpText<"Treat pointer overflow as two's complement">;
+def fno_wrapv_pointer : Flag<["-"], "fno-wrapv-pointer">, Group,
+  Visibility<[ClangOption, CLOption, FlangOption]>;
 def fwritable_strings : Flag<["-"], "fwritable-strings">, Group,
   Visibility<[ClangOption, CC1Option]>,
   HelpText<"Store string literals as writable data">,
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-10 Thread Nikita Popov via cfe-commits 

https://github.com/nikic updated 
https://github.com/llvm/llvm-project/pull/122486

>From b8c7a369fffecc9d1811d286fb1536346045fb74 Mon Sep 17 00:00:00 2001
From: Nikita Popov 
Date: Fri, 10 Jan 2025 17:01:07 +0100
Subject: [PATCH] [Clang] Add -fwrapv-pointer flag

GCC supports three flags related to overflow behavior:
 * `-fwrapv`: Makes signed integer overflow well-defined.
 * `-fwrapv-pointer`: Makes pointer overflow well-defined.
 * `-fno-strict-overflow`: Implies `-fwrapv -fwrapv-pointer`,
   making both signed integer overflow and pointer overflow
   well-defined.

Clang currently only supports `-fno-strict-overflow` and `-fwrapv`,
but not `-fwrapv-pointer`.

This PR proposes to introduce `-fwrapv-pointer` and adjust the
semantics of `-fwrapv` to match GCC.

This allows signed integer overflow and pointer overflow to be
controlled independently, while `-fno-strict-overflow` still
exists to control both at the same time (and that option is
consistent across GCC and Clang).
---
 clang/docs/ReleaseNotes.rst   | 11 ++
 clang/include/clang/Basic/LangOptions.def |  1 +
 clang/include/clang/Driver/Options.td |  5 +
 clang/lib/CodeGen/CGBuiltin.cpp   |  2 +-
 clang/lib/CodeGen/CGExpr.cpp  | 22 +--
 clang/lib/CodeGen/CGExprScalar.cpp| 12 +-
 clang/lib/Driver/SanitizerArgs.cpp|  3 +++
 clang/lib/Driver/ToolChains/CommonArgs.cpp| 15 +
 clang/lib/Frontend/CompilerInvocation.cpp |  4 
 clang/lib/Sema/SemaExpr.cpp   |  2 +-
 clang/test/CodeGen/integer-overflow.c | 13 ++-
 clang/test/CodeGen/pointer-overflow.c | 12 ++
 clang/test/Driver/clang_wrapv_opts.c  | 19 +---
 .../Sema/tautological-pointer-comparison.c|  2 +-
 14 files changed, 85 insertions(+), 38 deletions(-)
 create mode 100644 clang/test/CodeGen/pointer-overflow.c

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 511a28c5554bbb..44d98d98411d12 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -58,6 +58,12 @@ code bases.
   containing strict-aliasing violations. The new default behavior can be
   disabled using ``-fno-pointer-tbaa``.
 
+- The ``-fwrapv`` flag now only makes signed integer overflow well-defined,
+  without affecting pointer overflow, which is controlled by a new
+  ``-fwrapv-pointer`` flag. The ``-fno-strict-overflow`` flag now implies
+  both ``-fwrapv`` and ``-fwrapv-pointer`` and as such retains its old meaning.
+  The new behavior matches GCC.
+
 C/C++ Language Potentially Breaking Changes
 ---
 
@@ -464,6 +470,11 @@ New Compiler Flags
 - clang-cl and clang-dxc now support 
``-fdiagnostics-color=[auto|never|always]``
   in addition to ``-f[no-]color-diagnostics``.
 
+- The new ``-fwrapv-pointer`` flag opts-in to a language dialect where pointer
+  overflow is well-defined. The ``-fwrapv`` flag previously implied
+  ``-fwrapv-pointer`` as well, but no longer does. ``-fno-strict-overflow``
+  implies ``-fwrapv -fwrapv-pointer``. The flags now match GCC.
+
 Deprecated Compiler Flags
 -
 
diff --git a/clang/include/clang/Basic/LangOptions.def 
b/clang/include/clang/Basic/LangOptions.def
index 3b833240e5b68c..c4c53d7455c417 100644
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -407,6 +407,7 @@ VALUE_LANGOPT(TrivialAutoVarInitMaxSize, 32, 0,
  "stop trivial automatic variable initialization if var size 
exceeds the specified size (in bytes). Must be greater than 0.")
 ENUM_LANGOPT(SignedOverflowBehavior, SignedOverflowBehaviorTy, 2, 
SOB_Undefined,
  "signed integer overflow handling")
+LANGOPT(PointerOverflowDefined, 1, 0, "make pointer overflow defined")
 ENUM_LANGOPT(ThreadModel  , ThreadModelKind, 2, ThreadModelKind::POSIX, 
"Thread Model")
 
 BENIGN_LANGOPT(ArrowDepth, 32, 256,
diff --git a/clang/include/clang/Driver/Options.td 
b/clang/include/clang/Driver/Options.td
index 41a7e8c3728066..8b45aa6dd4c2df 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -4291,6 +4291,11 @@ def fwrapv : Flag<["-"], "fwrapv">, Group,
   HelpText<"Treat signed integer overflow as two's complement">;
 def fno_wrapv : Flag<["-"], "fno-wrapv">, Group,
   Visibility<[ClangOption, CLOption, FlangOption]>;
+def fwrapv_pointer : Flag<["-"], "fwrapv-pointer">, Group,
+  Visibility<[ClangOption, CLOption, CC1Option, FlangOption, FC1Option]>,
+  HelpText<"Treat pointer overflow as two's complement">;
+def fno_wrapv_pointer : Flag<["-"], "fno-wrapv-pointer">, Group,
+  Visibility<[ClangOption, CLOption, FlangOption]>;
 def fwritable_strings : Flag<["-"], "fwritable-strings">, Group,
   Visibility<[ClangOption, CC1Option]>,
   HelpText<"Store string literals as writable data">,
diff --git a/clang/lib/CodeGen/CGBuiltin.cp

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-10 Thread via cfe-commits 

github-actions[bot] wrote:




:warning: C/C++ code formatter, clang-format found issues in your code. 
:warning:



You can test this locally with the following command:


``bash
git-clang-format --diff c39500f88c93f668c68bdafe56bd8d16e8abbec1 
32fe619505787c434f97b01da0458ba7861f9550 --extensions c,cpp -- 
clang/lib/CodeGen/CGBuiltin.cpp clang/lib/CodeGen/CGExpr.cpp 
clang/lib/CodeGen/CGExprScalar.cpp clang/lib/Driver/SanitizerArgs.cpp 
clang/lib/Driver/ToolChains/CommonArgs.cpp 
clang/lib/Frontend/CompilerInvocation.cpp clang/lib/Sema/SemaExpr.cpp 
clang/test/CodeGen/integer-overflow.c clang/test/Driver/clang_wrapv_opts.c 
clang/test/Sema/tautological-pointer-comparison.c
``





View the diff from clang-format here.


``diff
diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index dc9c2afeaa..6fd9e82292 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -4413,10 +4413,9 @@ LValue CodeGenFunction::EmitArraySubscriptExpr(const 
ArraySubscriptExpr *E,
 Addr = EmitPointerWithAlignment(E->getBase(), &EltBaseInfo, &EltTBAAInfo);
 auto *Idx = EmitIdxAfterBase(/*Promote*/true);
 QualType ptrType = E->getBase()->getType();
-Addr = emitArraySubscriptGEP(*this, Addr, Idx, E->getType(),
- !getLangOpts().PointerOverflowDefined,
- SignedIndices, E->getExprLoc(), &ptrType,
- E->getBase());
+Addr = emitArraySubscriptGEP(
+*this, Addr, Idx, E->getType(), !getLangOpts().PointerOverflowDefined,
+SignedIndices, E->getExprLoc(), &ptrType, E->getBase());
   }
 
   LValue LV = MakeAddrLValue(Addr, E->getType(), EltBaseInfo, EltTBAAInfo);

``




https://github.com/llvm/llvm-project/pull/122486
___
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-10 Thread via cfe-commits 

llvmbot wrote:




@llvm/pr-subscribers-clang-driver

Author: Nikita Popov (nikic)


Changes

GCC supports three flags related to overflow behavior:
 * `-fwrapv`: Makes signed integer overflow well-defined.
 * `-fwrapv-pointer`: Makes pointer overflow well-defined.
 * `-fno-strict-overflow`: Implies `-fwrapv -fwrapv-pointer`, making both 
signed integer overflow and pointer overflow well-defined.

Clang currently only supports `-fno-strict-overflow` and `-fwrapv`, but not 
`-fwrapv-pointer`.

This PR proposes to introduce `-fwrapv-pointer` and adjust the semantics of 
`-fwrapv` to match GCC.

This allows signed integer overflow and pointer overflow to be controlled 
independently, while `-fno-strict-overflow` still exists to control both at the 
same time (and that option is consistent across GCC and Clang).

---
Full diff: https://github.com/llvm/llvm-project/pull/122486.diff


13 Files Affected:

- (modified) clang/docs/ReleaseNotes.rst (+11) 
- (modified) clang/include/clang/Basic/LangOptions.def (+1) 
- (modified) clang/include/clang/Driver/Options.td (+5) 
- (modified) clang/lib/CodeGen/CGBuiltin.cpp (+1-1) 
- (modified) clang/lib/CodeGen/CGExpr.cpp (+11-11) 
- (modified) clang/lib/CodeGen/CGExprScalar.cpp (+6-6) 
- (modified) clang/lib/Driver/SanitizerArgs.cpp (+3) 
- (modified) clang/lib/Driver/ToolChains/CommonArgs.cpp (+11-4) 
- (modified) clang/lib/Frontend/CompilerInvocation.cpp (+4) 
- (modified) clang/lib/Sema/SemaExpr.cpp (+1-1) 
- (modified) clang/test/CodeGen/integer-overflow.c (+2-11) 
- (modified) clang/test/Driver/clang_wrapv_opts.c (+16-3) 
- (modified) clang/test/Sema/tautological-pointer-comparison.c (+1-1) 


``diff
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 511a28c5554bbb..44d98d98411d12 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -58,6 +58,12 @@ code bases.
   containing strict-aliasing violations. The new default behavior can be
   disabled using ``-fno-pointer-tbaa``.
 
+- The ``-fwrapv`` flag now only makes signed integer overflow well-defined,
+  without affecting pointer overflow, which is controlled by a new
+  ``-fwrapv-pointer`` flag. The ``-fno-strict-overflow`` flag now implies
+  both ``-fwrapv`` and ``-fwrapv-pointer`` and as such retains its old meaning.
+  The new behavior matches GCC.
+
 C/C++ Language Potentially Breaking Changes
 ---
 
@@ -464,6 +470,11 @@ New Compiler Flags
 - clang-cl and clang-dxc now support 
``-fdiagnostics-color=[auto|never|always]``
   in addition to ``-f[no-]color-diagnostics``.
 
+- The new ``-fwrapv-pointer`` flag opts-in to a language dialect where pointer
+  overflow is well-defined. The ``-fwrapv`` flag previously implied
+  ``-fwrapv-pointer`` as well, but no longer does. ``-fno-strict-overflow``
+  implies ``-fwrapv -fwrapv-pointer``. The flags now match GCC.
+
 Deprecated Compiler Flags
 -
 
diff --git a/clang/include/clang/Basic/LangOptions.def 
b/clang/include/clang/Basic/LangOptions.def
index 3b833240e5b68c..c4c53d7455c417 100644
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -407,6 +407,7 @@ VALUE_LANGOPT(TrivialAutoVarInitMaxSize, 32, 0,
  "stop trivial automatic variable initialization if var size 
exceeds the specified size (in bytes). Must be greater than 0.")
 ENUM_LANGOPT(SignedOverflowBehavior, SignedOverflowBehaviorTy, 2, 
SOB_Undefined,
  "signed integer overflow handling")
+LANGOPT(PointerOverflowDefined, 1, 0, "make pointer overflow defined")
 ENUM_LANGOPT(ThreadModel  , ThreadModelKind, 2, ThreadModelKind::POSIX, 
"Thread Model")
 
 BENIGN_LANGOPT(ArrowDepth, 32, 256,
diff --git a/clang/include/clang/Driver/Options.td 
b/clang/include/clang/Driver/Options.td
index 41a7e8c3728066..8b45aa6dd4c2df 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -4291,6 +4291,11 @@ def fwrapv : Flag<["-"], "fwrapv">, Group,
   HelpText<"Treat signed integer overflow as two's complement">;
 def fno_wrapv : Flag<["-"], "fno-wrapv">, Group,
   Visibility<[ClangOption, CLOption, FlangOption]>;
+def fwrapv_pointer : Flag<["-"], "fwrapv-pointer">, Group,
+  Visibility<[ClangOption, CLOption, CC1Option, FlangOption, FC1Option]>,
+  HelpText<"Treat pointer overflow as two's complement">;
+def fno_wrapv_pointer : Flag<["-"], "fno-wrapv-pointer">, Group,
+  Visibility<[ClangOption, CLOption, FlangOption]>;
 def fwritable_strings : Flag<["-"], "fwritable-strings">, Group,
   Visibility<[ClangOption, CC1Option]>,
   HelpText<"Store string literals as writable data">,
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index ca03fb665d423d..b5bbfeae576029 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -22113,7 +22113,7 @@ RValue CodeGenFunction::EmitBuiltinAlignTo(const 
CallExpr *E, bool AlignUp) {
 // By adding the ma

[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

2025-01-10 Thread Nikita Popov via cfe-commits 

https://github.com/nikic created 
https://github.com/llvm/llvm-project/pull/122486

GCC supports three flags related to overflow behavior:
 * `-fwrapv`: Makes signed integer overflow well-defined.
 * `-fwrapv-pointer`: Makes pointer overflow well-defined.
 * `-fno-strict-overflow`: Implies `-fwrapv -fwrapv-pointer`, making both 
signed integer overflow and pointer overflow well-defined.

Clang currently only supports `-fno-strict-overflow` and `-fwrapv`, but not 
`-fwrapv-pointer`.

This PR proposes to introduce `-fwrapv-pointer` and adjust the semantics of 
`-fwrapv` to match GCC.

This allows signed integer overflow and pointer overflow to be controlled 
independently, while `-fno-strict-overflow` still exists to control both at the 
same time (and that option is consistent across GCC and Clang).

>From 32fe619505787c434f97b01da0458ba7861f9550 Mon Sep 17 00:00:00 2001
From: Nikita Popov 
Date: Fri, 10 Jan 2025 17:01:07 +0100
Subject: [PATCH] [Clang] Add -fwrapv-pointer flag

GCC supports three flags related to overflow behavior:
 * `-fwrapv`: Makes signed integer overflow well-defined.
 * `-fwrapv-pointer`: Makes pointer overflow well-defined.
 * `-fno-strict-overflow`: Implies `-fwrapv -fwrapv-pointer`,
   making both signed integer overflow and pointer overflow
   well-defined.

Clang currently only supports `-fno-strict-overflow` and `-fwrapv`,
but not `-fwrapv-pointer`.

This PR proposes to introduce `-fwrapv-pointer` and adjust the
semantics of `-fwrapv` to match GCC.

This allows signed integer overflow and pointer overflow to be
controlled independently, while `-fno-strict-overflow` still
exists to control both at the same time (and that option is
consistent across GCC and Clang).
---
 clang/docs/ReleaseNotes.rst   | 11 ++
 clang/include/clang/Basic/LangOptions.def |  1 +
 clang/include/clang/Driver/Options.td |  5 +
 clang/lib/CodeGen/CGBuiltin.cpp   |  2 +-
 clang/lib/CodeGen/CGExpr.cpp  | 22 +--
 clang/lib/CodeGen/CGExprScalar.cpp| 12 +-
 clang/lib/Driver/SanitizerArgs.cpp|  3 +++
 clang/lib/Driver/ToolChains/CommonArgs.cpp| 15 +
 clang/lib/Frontend/CompilerInvocation.cpp |  4 
 clang/lib/Sema/SemaExpr.cpp   |  2 +-
 clang/test/CodeGen/integer-overflow.c | 13 ++-
 clang/test/Driver/clang_wrapv_opts.c  | 19 +---
 .../Sema/tautological-pointer-comparison.c|  2 +-
 13 files changed, 73 insertions(+), 38 deletions(-)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 511a28c5554bbb..44d98d98411d12 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -58,6 +58,12 @@ code bases.
   containing strict-aliasing violations. The new default behavior can be
   disabled using ``-fno-pointer-tbaa``.
 
+- The ``-fwrapv`` flag now only makes signed integer overflow well-defined,
+  without affecting pointer overflow, which is controlled by a new
+  ``-fwrapv-pointer`` flag. The ``-fno-strict-overflow`` flag now implies
+  both ``-fwrapv`` and ``-fwrapv-pointer`` and as such retains its old meaning.
+  The new behavior matches GCC.
+
 C/C++ Language Potentially Breaking Changes
 ---
 
@@ -464,6 +470,11 @@ New Compiler Flags
 - clang-cl and clang-dxc now support 
``-fdiagnostics-color=[auto|never|always]``
   in addition to ``-f[no-]color-diagnostics``.
 
+- The new ``-fwrapv-pointer`` flag opts-in to a language dialect where pointer
+  overflow is well-defined. The ``-fwrapv`` flag previously implied
+  ``-fwrapv-pointer`` as well, but no longer does. ``-fno-strict-overflow``
+  implies ``-fwrapv -fwrapv-pointer``. The flags now match GCC.
+
 Deprecated Compiler Flags
 -
 
diff --git a/clang/include/clang/Basic/LangOptions.def 
b/clang/include/clang/Basic/LangOptions.def
index 3b833240e5b68c..c4c53d7455c417 100644
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -407,6 +407,7 @@ VALUE_LANGOPT(TrivialAutoVarInitMaxSize, 32, 0,
  "stop trivial automatic variable initialization if var size 
exceeds the specified size (in bytes). Must be greater than 0.")
 ENUM_LANGOPT(SignedOverflowBehavior, SignedOverflowBehaviorTy, 2, 
SOB_Undefined,
  "signed integer overflow handling")
+LANGOPT(PointerOverflowDefined, 1, 0, "make pointer overflow defined")
 ENUM_LANGOPT(ThreadModel  , ThreadModelKind, 2, ThreadModelKind::POSIX, 
"Thread Model")
 
 BENIGN_LANGOPT(ArrowDepth, 32, 256,
diff --git a/clang/include/clang/Driver/Options.td 
b/clang/include/clang/Driver/Options.td
index 41a7e8c3728066..8b45aa6dd4c2df 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -4291,6 +4291,11 @@ def fwrapv : Flag<["-"], "fwrapv">, Group,
   HelpText<"Treat signed integer overflow as two's complement">;
 def fno_wrapv