This revision was automatically updated to reflect the committed changes.
Closed by commit rG329ef60f3e21: [Clang] support for outputs along indirect
edges of asm goto (authored by nickdesaulniers).
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D136497/new/
https://reviews.llvm.org/D136497
Files:
clang/docs/LanguageExtensions.rst
clang/docs/ReleaseNotes.rst
clang/lib/CodeGen/CGStmt.cpp
clang/test/CodeGen/asm-goto.c
clang/test/CodeGen/asm-goto2.c
clang/test/Modules/asm-goto.c
Index: clang/test/Modules/asm-goto.c
===================================================================
--- clang/test/Modules/asm-goto.c
+++ clang/test/Modules/asm-goto.c
@@ -5,7 +5,7 @@
// CHECK-LABEL: define {{.*}} @foo(
// CHECK: callbr {{.*}} "=r,!i{{.*}}()
-// CHECK-NEXT: to label %asm.fallthrough [label %indirect]
+// CHECK-NEXT: to label %asm.fallthrough [label %indirect.split]
int bar(void) {
return foo();
Index: clang/test/CodeGen/asm-goto2.c
===================================================================
--- /dev/null
+++ clang/test/CodeGen/asm-goto2.c
@@ -0,0 +1,156 @@
+// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py
+// REQUIRES: x86-registered-target
+// RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -O0 -emit-llvm %s -o - | FileCheck %s
+
+// CHECK-LABEL: @test0(
+// CHECK-NEXT: entry:
+// CHECK-NEXT: [[RET:%.*]] = alloca i32, align 4
+// CHECK-NEXT: [[TMP0:%.*]] = callbr i32 asm "", "=r,!i,~{dirflag},~{fpsr},~{flags}"() #[[ATTR1:[0-9]+]]
+// CHECK-NEXT: to label [[ASM_FALLTHROUGH:%.*]] [label %z.split], !srcloc !2
+// CHECK: asm.fallthrough:
+// CHECK-NEXT: store i32 [[TMP0]], ptr [[RET]], align 4
+// CHECK-NEXT: store i32 42, ptr [[RET]], align 4
+// CHECK-NEXT: br label [[Z:%.*]]
+// CHECK: z:
+// CHECK-NEXT: [[TMP1:%.*]] = load i32, ptr [[RET]], align 4
+// CHECK-NEXT: ret i32 [[TMP1]]
+// CHECK: z.split:
+// CHECK-NEXT: store i32 [[TMP0]], ptr [[RET]], align 4
+// CHECK-NEXT: br label [[Z]]
+//
+int test0 (void) {
+ int ret;
+ asm goto ("" : "=r"(ret):::z);
+ ret = 42;
+z:
+ return ret;
+}
+
+// CHECK-LABEL: @test1(
+// CHECK-NEXT: entry:
+// CHECK-NEXT: [[RET:%.*]] = alloca i32, align 4
+// CHECK-NEXT: [[B:%.*]] = alloca i32, align 4
+// CHECK-NEXT: [[TMP0:%.*]] = callbr { i32, i32 } asm "", "=r,=r,!i,~{dirflag},~{fpsr},~{flags}"() #[[ATTR1]]
+// CHECK-NEXT: to label [[ASM_FALLTHROUGH:%.*]] [label %z.split], !srcloc !3
+// CHECK: asm.fallthrough:
+// CHECK-NEXT: [[ASMRESULT:%.*]] = extractvalue { i32, i32 } [[TMP0]], 0
+// CHECK-NEXT: [[ASMRESULT1:%.*]] = extractvalue { i32, i32 } [[TMP0]], 1
+// CHECK-NEXT: store i32 [[ASMRESULT]], ptr [[RET]], align 4
+// CHECK-NEXT: store i32 [[ASMRESULT1]], ptr [[B]], align 4
+// CHECK-NEXT: store i32 42, ptr [[RET]], align 4
+// CHECK-NEXT: br label [[Z:%.*]]
+// CHECK: z:
+// CHECK-NEXT: [[TMP1:%.*]] = load i32, ptr [[RET]], align 4
+// CHECK-NEXT: ret i32 [[TMP1]]
+// CHECK: z.split:
+// CHECK-NEXT: [[ASMRESULT2:%.*]] = extractvalue { i32, i32 } [[TMP0]], 0
+// CHECK-NEXT: [[ASMRESULT3:%.*]] = extractvalue { i32, i32 } [[TMP0]], 1
+// CHECK-NEXT: store i32 [[ASMRESULT2]], ptr [[RET]], align 4
+// CHECK-NEXT: store i32 [[ASMRESULT3]], ptr [[B]], align 4
+// CHECK-NEXT: br label [[Z]]
+//
+int test1 (void) {
+ int ret, b;
+ asm goto ("" : "=r"(ret), "=r"(b):::z);
+ ret = 42;
+z:
+ return ret;
+}
+
+// CHECK-LABEL: @test2(
+// CHECK-NEXT: entry:
+// CHECK-NEXT: [[RET:%.*]] = alloca i32, align 4
+// CHECK-NEXT: [[B:%.*]] = alloca i32, align 4
+// CHECK-NEXT: [[TMP0:%.*]] = callbr { i32, i32 } asm "", "=r,=r,!i,~{dirflag},~{fpsr},~{flags}"() #[[ATTR1]]
+// CHECK-NEXT: to label [[ASM_FALLTHROUGH:%.*]] [label %z.split], !srcloc !4
+// CHECK: asm.fallthrough:
+// CHECK-NEXT: [[ASMRESULT:%.*]] = extractvalue { i32, i32 } [[TMP0]], 0
+// CHECK-NEXT: [[ASMRESULT1:%.*]] = extractvalue { i32, i32 } [[TMP0]], 1
+// CHECK-NEXT: store i32 [[ASMRESULT]], ptr [[RET]], align 4
+// CHECK-NEXT: store i32 [[ASMRESULT1]], ptr [[B]], align 4
+// CHECK-NEXT: [[TMP1:%.*]] = callbr { i32, i32 } asm "", "=r,=r,!i,~{dirflag},~{fpsr},~{flags}"() #[[ATTR1]]
+// CHECK-NEXT: to label [[ASM_FALLTHROUGH4:%.*]] [label %z.split9], !srcloc !5
+// CHECK: asm.fallthrough4:
+// CHECK-NEXT: [[ASMRESULT5:%.*]] = extractvalue { i32, i32 } [[TMP1]], 0
+// CHECK-NEXT: [[ASMRESULT6:%.*]] = extractvalue { i32, i32 } [[TMP1]], 1
+// CHECK-NEXT: store i32 [[ASMRESULT5]], ptr [[RET]], align 4
+// CHECK-NEXT: store i32 [[ASMRESULT6]], ptr [[B]], align 4
+// CHECK-NEXT: br label [[Z:%.*]]
+// CHECK: z:
+// CHECK-NEXT: [[TMP2:%.*]] = load i32, ptr [[RET]], align 4
+// CHECK-NEXT: ret i32 [[TMP2]]
+// CHECK: z.split:
+// CHECK-NEXT: [[ASMRESULT2:%.*]] = extractvalue { i32, i32 } [[TMP0]], 0
+// CHECK-NEXT: [[ASMRESULT3:%.*]] = extractvalue { i32, i32 } [[TMP0]], 1
+// CHECK-NEXT: store i32 [[ASMRESULT2]], ptr [[RET]], align 4
+// CHECK-NEXT: store i32 [[ASMRESULT3]], ptr [[B]], align 4
+// CHECK-NEXT: br label [[Z]]
+// CHECK: z.split9:
+// CHECK-NEXT: [[ASMRESULT7:%.*]] = extractvalue { i32, i32 } [[TMP1]], 0
+// CHECK-NEXT: [[ASMRESULT8:%.*]] = extractvalue { i32, i32 } [[TMP1]], 1
+// CHECK-NEXT: store i32 [[ASMRESULT7]], ptr [[RET]], align 4
+// CHECK-NEXT: store i32 [[ASMRESULT8]], ptr [[B]], align 4
+// CHECK-NEXT: br label [[Z]]
+//
+int test2 (void) {
+ int ret, b;
+ asm goto ("" : "=r"(ret), "=r"(b):::z);
+ asm goto ("" : "=r"(ret), "=r"(b):::z);
+z:
+ return ret;
+}
+// CHECK-LABEL: @test3(
+// CHECK-NEXT: entry:
+// CHECK-NEXT: [[RETVAL:%.*]] = alloca i32, align 4
+// CHECK-NEXT: [[OUT1_ADDR:%.*]] = alloca i32, align 4
+// CHECK-NEXT: store i32 [[OUT1:%.*]], ptr [[OUT1_ADDR]], align 4
+// CHECK-NEXT: [[TMP0:%.*]] = callbr i32 asm "", "=r,!i,!i,~{dirflag},~{fpsr},~{flags}"() #[[ATTR1]]
+// CHECK-NEXT: to label [[ASM_FALLTHROUGH:%.*]] [label [[LABEL_TRUE_SPLIT:%.*]], label %loop.split], !srcloc !6
+// CHECK: asm.fallthrough:
+// CHECK-NEXT: store i32 [[TMP0]], ptr [[OUT1_ADDR]], align 4
+// CHECK-NEXT: store i32 0, ptr [[RETVAL]], align 4
+// CHECK-NEXT: br label [[RETURN:%.*]]
+// CHECK: label_true.split:
+// CHECK-NEXT: store i32 [[TMP0]], ptr [[OUT1_ADDR]], align 4
+// CHECK-NEXT: br label [[LABEL_TRUE:%.*]]
+// CHECK: loop.split:
+// CHECK-NEXT: store i32 [[TMP0]], ptr [[OUT1_ADDR]], align 4
+// CHECK-NEXT: br label [[LOOP:%.*]]
+// CHECK: loop:
+// CHECK-NEXT: store i32 0, ptr [[RETVAL]], align 4
+// CHECK-NEXT: br label [[RETURN]]
+// CHECK: label_true:
+// CHECK-NEXT: store i32 1, ptr [[RETVAL]], align 4
+// CHECK-NEXT: br label [[RETURN]]
+// CHECK: return:
+// CHECK-NEXT: [[TMP1:%.*]] = load i32, ptr [[RETVAL]], align 4
+// CHECK-NEXT: ret i32 [[TMP1]]
+//
+int test3 (int out1) {
+ asm goto("" : "=r"(out1)::: label_true, loop);
+ return 0;
+loop:
+ return 0;
+label_true:
+ return 1;
+}
+
+// CHECK-LABEL: @test4(
+// CHECK-NEXT: entry:
+// CHECK-NEXT: [[X:%.*]] = alloca i32, align 4
+// CHECK-NEXT: br label [[FOO:%.*]]
+// CHECK: foo:
+// CHECK-NEXT: [[TMP0:%.*]] = callbr i32 asm "", "=r,!i,~{dirflag},~{fpsr},~{flags}"() #[[ATTR1]]
+// CHECK-NEXT: to label [[ASM_FALLTHROUGH:%.*]] [label %foo.split], !srcloc !7
+// CHECK: asm.fallthrough:
+// CHECK-NEXT: store i32 [[TMP0]], ptr [[X]], align 4
+// CHECK-NEXT: ret void
+// CHECK: foo.split:
+// CHECK-NEXT: store i32 [[TMP0]], ptr [[X]], align 4
+// CHECK-NEXT: br label [[FOO]]
+//
+void test4 (void) {
+ int x;
+foo:
+ asm goto ("" : "=r"(x):::foo);
+}
Index: clang/test/CodeGen/asm-goto.c
===================================================================
--- clang/test/CodeGen/asm-goto.c
+++ clang/test/CodeGen/asm-goto.c
@@ -22,12 +22,12 @@
int test2(int cond) {
// CHECK-LABEL: define{{.*}} i32 @test2(
// CHECK: callbr i32 asm sideeffect
- // CHECK: to label %asm.fallthrough [label %label_true, label %loop]
+ // CHECK: to label %asm.fallthrough [label %label_true.split, label %loop.split]
// CHECK-LABEL: asm.fallthrough:
asm volatile goto("testl %0, %0; jne %l2;" : "=r"(cond) : "r"(cond) :: label_true, loop);
asm volatile goto("testl %0, %0; jne %l3;" : "=r"(cond) : "r"(cond) :: label_true, loop);
// CHECK: callbr i32 asm sideeffect
- // CHECK: to label %asm.fallthrough1 [label %label_true, label %loop]
+ // CHECK: to label %asm.fallthrough1 [label %label_true.split2, label %loop.split3]
// CHECK-LABEL: asm.fallthrough1:
return 0;
loop:
@@ -39,13 +39,13 @@
int test3(int out1, int out2) {
// CHECK-LABEL: define{{.*}} i32 @test3(
// CHECK: callbr { i32, i32 } asm sideeffect
- // CHECK: to label %asm.fallthrough [label %label_true, label %loop]
+ // CHECK: to label %asm.fallthrough [label %label_true.split, label %loop.split]
// CHECK-LABEL: asm.fallthrough:
asm volatile goto("testl %0, %0; jne %l3;" : "=r"(out1), "=r"(out2) : "r"(out1) :: label_true, loop);
asm volatile goto("testl %0, %0; jne %l4;" : "=r"(out1), "=r"(out2) : "r"(out1) :: label_true, loop);
// CHECK: callbr { i32, i32 } asm sideeffect
- // CHECK: to label %asm.fallthrough2 [label %label_true, label %loop]
- // CHECK-LABEL: asm.fallthrough2:
+ // CHECK: to label %asm.fallthrough6 [label %label_true.split11, label %loop.split14]
+ // CHECK-LABEL: asm.fallthrough6:
return 0;
loop:
return 0;
@@ -56,15 +56,15 @@
int test4(int out1, int out2) {
// CHECK-LABEL: define{{.*}} i32 @test4(
// CHECK: callbr { i32, i32 } asm sideeffect "jne ${5:l}", "={si},={di},r,0,1,!i,!i
- // CHECK: to label %asm.fallthrough [label %label_true, label %loop]
+ // CHECK: to label %asm.fallthrough [label %label_true.split, label %loop.split]
// CHECK-LABEL: asm.fallthrough:
if (out1 < out2)
asm volatile goto("jne %l5" : "+S"(out1), "+D"(out2) : "r"(out1) :: label_true, loop);
else
asm volatile goto("jne %l7" : "+S"(out1), "+D"(out2) : "r"(out1), "r"(out2) :: label_true, loop);
// CHECK: callbr { i32, i32 } asm sideeffect "jne ${7:l}", "={si},={di},r,r,0,1,!i,!i
- // CHECK: to label %asm.fallthrough2 [label %label_true, label %loop]
- // CHECK-LABEL: asm.fallthrough2:
+ // CHECK: to label %asm.fallthrough6 [label %label_true.split11, label %loop.split14]
+ // CHECK-LABEL: asm.fallthrough6:
return out1 + out2;
loop:
return -1;
@@ -75,7 +75,7 @@
int test5(int addr, int size, int limit) {
// CHECK-LABEL: define{{.*}} i32 @test5(
// CHECK: callbr i32 asm "add $1,$0 ; jc ${4:l} ; cmp $2,$0 ; ja ${4:l} ; ", "=r,imr,imr,0,!i
- // CHECK: to label %asm.fallthrough [label %t_err]
+ // CHECK: to label %asm.fallthrough [label %t_err.split]
// CHECK-LABEL: asm.fallthrough:
asm goto(
"add %1,%0 ; "
@@ -93,7 +93,7 @@
int test6(int out1) {
// CHECK-LABEL: define{{.*}} i32 @test6(
// CHECK: callbr i32 asm sideeffect "testl $0, $0; testl $1, $1; jne ${3:l}", "={si},r,0,!i,!i,{{.*}}
- // CHECK: to label %asm.fallthrough [label %label_true, label %landing]
+ // CHECK: to label %asm.fallthrough [label %label_true.split, label %landing.split]
// CHECK-LABEL: asm.fallthrough:
// CHECK-LABEL: landing:
int out2 = 42;
@@ -111,7 +111,7 @@
void *test7(void) {
// CHECK-LABEL: define{{.*}} ptr @test7(
// CHECK: %1 = callbr ptr asm "# $0\0A\09# ${2:l}", "=r,0,!i,~{dirflag},~{fpsr},~{flags}"(ptr %0)
- // CHECK-NEXT: to label %asm.fallthrough [label %foo]
+ // CHECK-NEXT: to label %asm.fallthrough [label %foo.split]
void *p = &&foo;
asm goto ("# %0\n\t# %l2":"+r"(p):::foo);
foo:
@@ -123,7 +123,7 @@
void *test8(void) {
// CHECK-LABEL: define{{.*}} ptr @test8(
// CHECK: %1 = callbr ptr asm "# $0\0A\09# ${2:l}", "=r,0,!i,~{dirflag},~{fpsr},~{flags}"(ptr %0)
- // CHECK-NEXT: to label %asm.fallthrough [label %foo]
+ // CHECK-NEXT: to label %asm.fallthrough [label %foo.split]
void *p = &&foo;
asm goto ("# %0\n\t# %l[foo]":"+r"(p):::foo);
foo:
Index: clang/lib/CodeGen/CGStmt.cpp
===================================================================
--- clang/lib/CodeGen/CGStmt.cpp
+++ clang/lib/CodeGen/CGStmt.cpp
@@ -25,6 +25,7 @@
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/TargetInfo.h"
#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/IR/Assumptions.h"
@@ -2809,13 +2810,40 @@
FTy, AsmString, Constraints, HasSideEffect,
/* IsAlignStack */ false, AsmDialect, HasUnwindClobber);
std::vector<llvm::Value*> RegResults;
+ llvm::CallBrInst *CBR;
+ llvm::DenseMap<llvm::BasicBlock *, SmallVector<llvm::Value *, 4>>
+ CBRRegResults;
if (IsGCCAsmGoto) {
- llvm::CallBrInst *Result =
- Builder.CreateCallBr(IA, Fallthrough, Transfer, Args);
+ CBR = Builder.CreateCallBr(IA, Fallthrough, Transfer, Args);
EmitBlock(Fallthrough);
- UpdateAsmCallInst(*Result, HasSideEffect, false, ReadOnly, ReadNone,
+ UpdateAsmCallInst(*CBR, HasSideEffect, false, ReadOnly, ReadNone,
InNoMergeAttributedStmt, S, ResultRegTypes, ArgElemTypes,
*this, RegResults);
+ // Because we are emitting code top to bottom, we don't have enough
+ // information at this point to know precisely whether we have a critical
+ // edge. If we have outputs, split all indirect destinations.
+ if (!RegResults.empty()) {
+ unsigned i = 0;
+ for (llvm::BasicBlock *Dest : CBR->getIndirectDests()) {
+ llvm::Twine SynthName = Dest->getName() + ".split";
+ llvm::BasicBlock *SynthBB = createBasicBlock(SynthName);
+ llvm::IRBuilderBase::InsertPointGuard IPG(Builder);
+ Builder.SetInsertPoint(SynthBB);
+
+ if (ResultRegTypes.size() == 1) {
+ CBRRegResults[SynthBB].push_back(CBR);
+ } else {
+ for (unsigned j = 0, e = ResultRegTypes.size(); j != e; ++j) {
+ llvm::Value *Tmp = Builder.CreateExtractValue(CBR, j, "asmresult");
+ CBRRegResults[SynthBB].push_back(Tmp);
+ }
+ }
+
+ EmitBranch(Dest);
+ EmitBlock(SynthBB);
+ CBR->setIndirectDest(i++, SynthBB);
+ }
+ }
} else if (HasUnwindClobber) {
llvm::CallBase *Result = EmitCallOrInvoke(IA, Args, "");
UpdateAsmCallInst(*Result, HasSideEffect, true, ReadOnly, ReadNone,
@@ -2832,6 +2860,19 @@
EmitAsmStores(*this, S, RegResults, ResultRegTypes, ResultTruncRegTypes,
ResultRegDests, ResultRegQualTys, ResultTypeRequiresCast,
ResultRegIsFlagReg);
+
+ // If this is an asm goto with outputs, repeat EmitAsmStores, but with a
+ // different insertion point; one for each indirect destination and with
+ // CBRRegResults rather than RegResults.
+ if (IsGCCAsmGoto && !CBRRegResults.empty()) {
+ for (llvm::BasicBlock *Succ : CBR->getIndirectDests()) {
+ llvm::IRBuilderBase::InsertPointGuard IPG(Builder);
+ Builder.SetInsertPoint(Succ, --(Succ->end()));
+ EmitAsmStores(*this, S, CBRRegResults[Succ], ResultRegTypes,
+ ResultTruncRegTypes, ResultRegDests, ResultRegQualTys,
+ ResultTypeRequiresCast, ResultRegIsFlagReg);
+ }
+ }
}
LValue CodeGenFunction::InitCapturedStruct(const CapturedStmt &S) {
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -40,6 +40,16 @@
C/C++ Language Potentially Breaking Changes
-------------------------------------------
+- Indirect edges of asm goto statements under certain circumstances may now be
+ split. In previous releases of clang, that means for the following code the
+ two inputs may have compared equal in the inline assembly. This is no longer
+ guaranteed (and necessary to support outputs along indirect edges, which is
+ now supported as of this release). This change is more consistent with the
+ behavior of GCC.
+
+ .. code-block:: c
+
+ foo: asm goto ("# %0 %1"::"i"(&&foo)::foo);
C++ Specific Potentially Breaking Changes
-----------------------------------------
@@ -71,6 +81,9 @@
C Language Changes
------------------
+- Support for outputs from asm goto statements along indirect edges has been
+ added. This fixes
+ `Issue 53562 <https://github.com/llvm/llvm-project/issues/53562`_.
C2x Feature Support
^^^^^^^^^^^^^^^^^^^
Index: clang/docs/LanguageExtensions.rst
===================================================================
--- clang/docs/LanguageExtensions.rst
+++ clang/docs/LanguageExtensions.rst
@@ -1588,25 +1588,8 @@
ASM Goto with Output Constraints
================================
-.. note::
-
- Clang's implementation of ASM goto differs from `GCC's
- implementation <https://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html>`_ in
- that Clang doesn't yet support outputs on the indirect branch. Use of an
- output on the indirect branch may result in undefined behavior and should be
- avoided. E.g., in the following `z` isn't valid when used and may have
- different values depending on optimization levels. (Clang may not warn about
- such constructs.)
-
- .. code-block:: c++
-
- int foo(int x) {
- int y, z;
- asm goto(... : "=r"(y), "=r"(z): "r"(x) : : err);
- return y;
- err:
- return z;
- }
+Outputs may be used along any branches from the ``asm goto`` whether the
+branches are taken or not.
When using tied-outputs (i.e. outputs that are inputs and outputs, not just
outputs) with the `+r` constraint, there is a hidden input that's created
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