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[Clang] Reland '__has_builtin should return false for aux triple builtins' #126324

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Merged
merged 4 commits into from
Jul 28, 2025
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[Clang] Reland '__has_builtin should return false for aux triple builtins' #126324

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[clang] Reland '__has_builtin should return false for aux triple buil…
sarnex Jul 28, 2025
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sarnex Jul 28, 2025
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3 changes: 3 additions & 0 deletions clang/docs/LanguageExtensions.rst
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Expand Up @@ -68,6 +68,9 @@ It can be used like this:
``__has_builtin`` should not be used to detect support for a builtin macro;
use ``#ifdef`` instead.

When compiling with target offloading, ``__has_builtin`` only considers the
currently active target.

``__has_constexpr_builtin``
---------------------------

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2 changes: 2 additions & 0 deletions clang/docs/ReleaseNotes.rst
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Expand Up @@ -98,6 +98,8 @@ Non-comprehensive list of changes in this release
This feature is enabled by default but can be disabled by compiling with
``-fno-sanitize-annotate-debug-info-traps``.

- The ``__has_builtin`` function now only considers the currently active target when being used with target offloading.
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This should be moved to the potentially breaking changes section, because the behavioral change could catch folks off-guard.

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will do then merge, thanks!


New Compiler Flags
------------------
- New option ``-fno-sanitize-annotate-debug-info-traps`` added to disable emitting trap reasons into the debug info when compiling with trapping UBSan (e.g. ``-fsanitize-trap=undefined``).
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8 changes: 6 additions & 2 deletions clang/lib/Lex/PPMacroExpansion.cpp
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Expand Up @@ -1760,7 +1760,8 @@ void Preprocessor::ExpandBuiltinMacro(Token &Tok) {
Tok, *this, diag::err_feature_check_malformed);
if (!II)
return false;
else if (II->getBuiltinID() != 0) {
unsigned BuiltinID = II->getBuiltinID();
if (BuiltinID != 0) {
switch (II->getBuiltinID()) {
case Builtin::BI__builtin_cpu_is:
return getTargetInfo().supportsCpuIs();
Expand All @@ -1774,8 +1775,11 @@ void Preprocessor::ExpandBuiltinMacro(Token &Tok) {
// usual allocation and deallocation functions. Required by libc++
return 201802;
default:
// __has_builtin should return false for aux builtins.
if (getBuiltinInfo().isAuxBuiltinID(BuiltinID))
return false;
return Builtin::evaluateRequiredTargetFeatures(
getBuiltinInfo().getRequiredFeatures(II->getBuiltinID()),
getBuiltinInfo().getRequiredFeatures(BuiltinID),
getTargetInfo().getTargetOpts().FeatureMap);
}
return true;
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5 changes: 4 additions & 1 deletion clang/test/Headers/__cpuidex_conflict.c
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Expand Up @@ -3,7 +3,10 @@
// RUN: %clang_cc1 %s -ffreestanding -fms-extensions -fms-compatibility \
// RUN: -fms-compatibility-version=19.00 -triple x86_64-pc-windows-msvc -emit-llvm -o -
// %clang_cc1 %s -ffreestanding -triple x86_64-w64-windows-gnu -fms-extensions -emit-llvm -o -
// RUN: %clang_cc1 %s -ffreestanding -fopenmp -fopenmp-is-target-device -aux-triple x86_64-unknown-linux-gnu
//
// FIXME: See https://github.com/llvm/llvm-project/pull/121839 and
// FIXME: https://github.com/llvm/llvm-project/pull/126324
// RUN: not %clang_cc1 %s -ffreestanding -fopenmp -fopenmp-is-target-device -aux-triple x86_64-unknown-linux-gnu

typedef __SIZE_TYPE__ size_t;

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18 changes: 18 additions & 0 deletions clang/test/Preprocessor/builtin_aux_info.cpp
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@@ -0,0 +1,18 @@
// RUN: %clang_cc1 -fopenmp -triple=spirv64 -fopenmp-is-target-device \
// RUN: -aux-triple x86_64-linux-unknown -E %s | FileCheck -implicit-check-not=BAD %s

// RUN: %clang_cc1 -fopenmp -triple=nvptx64 -fopenmp-is-target-device \
// RUN: -aux-triple x86_64-linux-unknown -E %s | FileCheck -implicit-check-not=BAD %s

// RUN: %clang_cc1 -fopenmp -triple=amdgcn-amd-amdhsa -fopenmp-is-target-device \
// RUN: -aux-triple x86_64-linux-unknown -E %s | FileCheck -implicit-check-not=BAD %s

// RUN: %clang_cc1 -fopenmp -triple=aarch64 -fopenmp-is-target-device \
// RUN: -aux-triple x86_64-linux-unknown -E %s | FileCheck -implicit-check-not=BAD %s

// CHECK: GOOD
#if __has_builtin(__builtin_ia32_pause)
BAD
#else
GOOD
#endif