https://github.com/Disservin created https://github.com/llvm/llvm-project/pull/207502
Adds a `__attribute__((noipa))` attribute to clang, more info on this attribute can be found in #203304. We also set the noinline attribute on the targeted function as pointed out by @jryans in #203304. fixes https://github.com/llvm/llvm-project/issues/40819 Assisted by GPT 5.4 for tests >From 0f3be6f5f12219590ea10ff7cdd7e9bb0e60ba87 Mon Sep 17 00:00:00 2001 From: Disservin <[email protected]> Date: Sat, 4 Jul 2026 10:57:45 +0200 Subject: [PATCH 1/2] Add tests --- clang/test/CodeGen/attr-noipa.c | 28 +++++++++++++++++++ ...a-attribute-supported-attributes-list.test | 1 + clang/test/Sema/attr-noipa.c | 7 +++++ clang/test/Sema/attr-noipa.cpp | 7 +++++ 4 files changed, 43 insertions(+) create mode 100644 clang/test/CodeGen/attr-noipa.c create mode 100644 clang/test/Sema/attr-noipa.c create mode 100644 clang/test/Sema/attr-noipa.cpp diff --git a/clang/test/CodeGen/attr-noipa.c b/clang/test/CodeGen/attr-noipa.c new file mode 100644 index 0000000000000..82394793827f1 --- /dev/null +++ b/clang/test/CodeGen/attr-noipa.c @@ -0,0 +1,28 @@ +// RUN: %clang_cc1 -emit-llvm -x c %s -triple x86_64-unknown-linux-gnu -O1 -o - | FileCheck %s --check-prefix=C +// RUN: %clang_cc1 -emit-llvm -x c++ %s -triple x86_64-unknown-linux-gnu -std=c++23 -O1 -o - | FileCheck %s --check-prefix=CXX + +// C-LABEL: define {{.*}} @with_noipa( +// C-SAME: ) {{.*}}#[[NOIPA_ATTR:[0-9]+]] { +__attribute__((noipa)) int with_noipa(int x) { + return x + 1; +} + +// C-LABEL: define {{.*}} @without_noipa( +// C-SAME: ) {{.*}}#[[PLAIN_ATTR:[0-9]+]] { +int without_noipa(int x) { + return x - 1; +} + +// CXX-LABEL: define {{.*}} @_Z10with_noipai( +// CXX-SAME: ) {{.*}}#[[NOIPA_ATTR:[0-9]+]] { + +// CXX-LABEL: define {{.*}} @_Z13without_noipai( +// CXX-SAME: ) {{.*}}#[[PLAIN_ATTR:[0-9]+]] { + +// C: attributes #[[NOIPA_ATTR]] = { {{.*}}noipa{{.*}} } +// C: attributes #[[PLAIN_ATTR]] = { {{.*}} } +// C-NOT: attributes #[[PLAIN_ATTR]] = { {{.*}}noipa{{.*}} } + +// CXX: attributes #[[NOIPA_ATTR]] = { {{.*}}noipa{{.*}} } +// CXX: attributes #[[PLAIN_ATTR]] = { {{.*}} } +// CXX-NOT: attributes #[[PLAIN_ATTR]] = { {{.*}}noipa{{.*}} } diff --git a/clang/test/Misc/pragma-attribute-supported-attributes-list.test b/clang/test/Misc/pragma-attribute-supported-attributes-list.test index 8bca68e2119e7..f952a4e57543c 100644 --- a/clang/test/Misc/pragma-attribute-supported-attributes-list.test +++ b/clang/test/Misc/pragma-attribute-supported-attributes-list.test @@ -127,6 +127,7 @@ // CHECK-NEXT: NoDuplicate (SubjectMatchRule_function) // CHECK-NEXT: NoEscape (SubjectMatchRule_variable_is_parameter) // CHECK-NEXT: NoFieldProtection (SubjectMatchRule_field) +// CHECK-NEXT: NoIPA (SubjectMatchRule_function) // CHECK-NEXT: NoInline (SubjectMatchRule_function) // CHECK-NEXT: NoInstrumentFunction (SubjectMatchRule_function, SubjectMatchRule_objc_method) // CHECK-NEXT: NoMerge (SubjectMatchRule_function, SubjectMatchRule_variable) diff --git a/clang/test/Sema/attr-noipa.c b/clang/test/Sema/attr-noipa.c new file mode 100644 index 0000000000000..a22e04dd71ca3 --- /dev/null +++ b/clang/test/Sema/attr-noipa.c @@ -0,0 +1,7 @@ +// RUN: %clang_cc1 -verify -fsyntax-only %s + +__attribute__((noipa)) int a; // expected-warning {{'noipa' attribute only applies to functions}} + +__attribute__((noipa)) void t1(void); + +__attribute__((noipa(2))) void t2(void); // expected-error {{'noipa' attribute takes no arguments}} diff --git a/clang/test/Sema/attr-noipa.cpp b/clang/test/Sema/attr-noipa.cpp new file mode 100644 index 0000000000000..1d4cb60c84d0a --- /dev/null +++ b/clang/test/Sema/attr-noipa.cpp @@ -0,0 +1,7 @@ +// RUN: %clang_cc1 -verify -fsyntax-only %s + +__attribute__((noipa)) int a; // expected-warning {{'noipa' attribute only applies to functions}} + +__attribute__((noipa)) void t1(); + +__attribute__((noipa(2))) void t2(); // expected-error {{'noipa' attribute takes no arguments}} >From 10c677422bd1e1a166af928aaa943f9546b099ff Mon Sep 17 00:00:00 2001 From: Disservin <[email protected]> Date: Sat, 4 Jul 2026 10:57:55 +0200 Subject: [PATCH 2/2] [clang] Add noipa attribute --- clang/include/clang/Basic/Attr.td | 7 +++++++ clang/include/clang/Basic/AttrDocs.td | 10 ++++++++++ clang/lib/CodeGen/CodeGenModule.cpp | 6 ++++++ 3 files changed, 23 insertions(+) diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td index 3f57104d474a7..3123ae3d369c3 100644 --- a/clang/include/clang/Basic/Attr.td +++ b/clang/include/clang/Basic/Attr.td @@ -2420,6 +2420,13 @@ def NoOutline : DeclOrStmtAttr { let SimpleHandler = true; } +def NoIPA : InheritableAttr { + let Spellings = [GCC<"noipa">]; + let Subjects = SubjectList<[Function]>; + let Documentation = [NoIPADocs]; + let SimpleHandler = 1; +} + def NoMips16 : InheritableAttr, TargetSpecificAttr<TargetMips32> { let Spellings = [GCC<"nomips16">]; let Subjects = SubjectList<[Function], ErrorDiag>; diff --git a/clang/include/clang/Basic/AttrDocs.td b/clang/include/clang/Basic/AttrDocs.td index b67a5b076237c..37d0f303a8cfc 100644 --- a/clang/include/clang/Basic/AttrDocs.td +++ b/clang/include/clang/Basic/AttrDocs.td @@ -1043,6 +1043,16 @@ the opposite of inlining. It can help to reduce code size. }]; } +def NoIPADocs : Documentation { + let Category = DocCatFunction; + let Content = [{ +This function attribute suppresses interprocedural optimization involving the +annotated function. Clang lowers it to LLVM IR's ``noipa`` function attribute +and sets the ```noinline`` function attribute as well, unless always_inline +is specified. + }]; +} + def MustTailDocs : Documentation { let Category = DocCatStmt; let Content = [{ diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp index 813cd67e4dd51..c9ddfbaa9a4e7 100644 --- a/clang/lib/CodeGen/CodeGenModule.cpp +++ b/clang/lib/CodeGen/CodeGenModule.cpp @@ -3105,6 +3105,12 @@ void CodeGenModule::SetLLVMFunctionAttributesForDefinition(const Decl *D, if (CodeGenOpts.DisableOutlining || D->hasAttr<NoOutlineAttr>()) B.addAttribute(llvm::Attribute::NoOutline); + if (D->hasAttr<NoIPAAttr>()) { + B.addAttribute(llvm::Attribute::NoIPA); + if (!F->hasFnAttribute(llvm::Attribute::AlwaysInline)) + B.addAttribute(llvm::Attribute::NoInline); + } + F->addFnAttrs(B); llvm::MaybeAlign ExplicitAlignment; _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
