From 02a25279aedcd959d060bba585adc0fe1cec3782 Mon Sep 17 00:00:00 2001 From: Ryan Prichard Date: Thu, 21 Jul 2022 13:09:48 -0700 Subject: [Frontend] Correct values of ATOMIC_*_LOCK_FREE to match builtin Correct the logic used to set `ATOMIC_*_LOCK_FREE` preprocessor macros not to rely on the ABI alignment of types. Instead, just assume all those types are aligned correctly by default since clang uses safe alignment for `_Atomic` types even if the underlying types are aligned to a lower boundary by default. For example, the `long long` and `double` types on x86 are aligned to 32-bit boundary by default. However, `_Atomic long long` and `_Atomic double` are aligned to 64-bit boundary, therefore satisfying the requirements of lock-free atomic operations. This fixes PR #19355 by correcting the value of `__GCC_ATOMIC_LLONG_LOCK_FREE` on x86, and therefore also fixing the assumption made in libc++ tests. This also fixes PR #30581 by applying a consistent logic between the functions used to implement both interfaces. Reviewed By: hfinkel, efriedma Differential Revision: https://reviews.llvm.org/D28213 --- clang/lib/Frontend/InitPreprocessor.cpp | 10 ++++------ clang/test/Preprocessor/init-x86.c | 6 +++--- clang/test/Sema/atomic-ops.c | 4 ---- 3 files changed, 7 insertions(+), 13 deletions(-) (limited to 'clang') diff --git a/clang/lib/Frontend/InitPreprocessor.cpp b/clang/lib/Frontend/InitPreprocessor.cpp index 655490ba06e5..20bfbf144a30 100644 --- a/clang/lib/Frontend/InitPreprocessor.cpp +++ b/clang/lib/Frontend/InitPreprocessor.cpp @@ -298,12 +298,12 @@ static void DefineFastIntType(unsigned TypeWidth, bool IsSigned, /// Get the value the ATOMIC_*_LOCK_FREE macro should have for a type with /// the specified properties. -static const char *getLockFreeValue(unsigned TypeWidth, unsigned TypeAlign, - unsigned InlineWidth) { +static const char *getLockFreeValue(unsigned TypeWidth, unsigned InlineWidth) { // Fully-aligned, power-of-2 sizes no larger than the inline // width will be inlined as lock-free operations. - if (TypeWidth == TypeAlign && (TypeWidth & (TypeWidth - 1)) == 0 && - TypeWidth <= InlineWidth) + // Note: we do not need to check alignment since _Atomic(T) is always + // appropriately-aligned in clang. + if ((TypeWidth & (TypeWidth - 1)) == 0 && TypeWidth <= InlineWidth) return "2"; // "always lock free" // We cannot be certain what operations the lib calls might be // able to implement as lock-free on future processors. @@ -1142,7 +1142,6 @@ static void InitializePredefinedMacros(const TargetInfo &TI, #define DEFINE_LOCK_FREE_MACRO(TYPE, Type) \ Builder.defineMacro(Prefix + #TYPE "_LOCK_FREE", \ getLockFreeValue(TI.get##Type##Width(), \ - TI.get##Type##Align(), \ InlineWidthBits)); DEFINE_LOCK_FREE_MACRO(BOOL, Bool); DEFINE_LOCK_FREE_MACRO(CHAR, Char); @@ -1157,7 +1156,6 @@ static void InitializePredefinedMacros(const TargetInfo &TI, DEFINE_LOCK_FREE_MACRO(LLONG, LongLong); Builder.defineMacro(Prefix + "POINTER_LOCK_FREE", getLockFreeValue(TI.getPointerWidth(0), - TI.getPointerAlign(0), InlineWidthBits)); #undef DEFINE_LOCK_FREE_MACRO }; diff --git a/clang/test/Preprocessor/init-x86.c b/clang/test/Preprocessor/init-x86.c index 339941fcf3ee..9c4e328bdf79 100644 --- a/clang/test/Preprocessor/init-x86.c +++ b/clang/test/Preprocessor/init-x86.c @@ -185,9 +185,9 @@ // I386:#define __i386__ 1 // I386:#define i386 1 -// RUN: %clang_cc1 -E -dM -ffreestanding -fgnuc-version=4.2.1 -triple=i386-pc-linux-gnu -target-cpu pentium4 < /dev/null | FileCheck -match-full-lines -check-prefix I386-LINUX -check-prefix I386-LINUX-ALIGN32 %s -// RUN: %clang_cc1 -x c++ -E -dM -ffreestanding -fgnuc-version=4.2.1 -triple=i386-pc-linux-gnu -target-cpu pentium4 < /dev/null | FileCheck -match-full-lines -check-prefix I386-LINUX -check-prefix I386-LINUX-CXX -check-prefix I386-LINUX-ALIGN32 %s -// RUN: %clang_cc1 -E -dM -ffreestanding -fgnuc-version=4.2.1 -triple=i386-pc-linux-gnu -target-cpu pentium4 -malign-double < /dev/null | FileCheck -match-full-lines -check-prefix I386-LINUX -check-prefix I386-LINUX-ALIGN64 %s +// RUN: %clang_cc1 -E -dM -ffreestanding -fgnuc-version=4.2.1 -triple=i386-pc-linux-gnu -target-cpu i486 < /dev/null | FileCheck -match-full-lines -check-prefix I386-LINUX -check-prefix I386-LINUX-ALIGN32 %s +// RUN: %clang_cc1 -E -dM -ffreestanding -fgnuc-version=4.2.1 -triple=i386-pc-linux-gnu -target-cpu pentium4 < /dev/null | FileCheck -match-full-lines -check-prefix I386-LINUX -check-prefix I386-LINUX-ALIGN64 %s +// RUN: %clang_cc1 -x c++ -E -dM -ffreestanding -fgnuc-version=4.2.1 -triple=i386-pc-linux-gnu -target-cpu pentium4 < /dev/null | FileCheck -match-full-lines -check-prefix I386-LINUX -check-prefix I386-LINUX-ALIGN64 -check-prefix I386-LINUX-CXX %s // // I386-LINUX-NOT:#define _LP64 // I386-LINUX:#define __BIGGEST_ALIGNMENT__ 16 diff --git a/clang/test/Sema/atomic-ops.c b/clang/test/Sema/atomic-ops.c index 3ad469d33743..45196ea19783 100644 --- a/clang/test/Sema/atomic-ops.c +++ b/clang/test/Sema/atomic-ops.c @@ -33,11 +33,7 @@ _Static_assert(__GCC_ATOMIC_INT_LOCK_FREE == 2, ""); _Static_assert(__GCC_ATOMIC_INT_LOCK_FREE == __CLANG_ATOMIC_INT_LOCK_FREE, ""); _Static_assert(__GCC_ATOMIC_LONG_LOCK_FREE == 2, ""); _Static_assert(__GCC_ATOMIC_LONG_LOCK_FREE == __CLANG_ATOMIC_LONG_LOCK_FREE, ""); -#ifdef __i386__ -_Static_assert(__GCC_ATOMIC_LLONG_LOCK_FREE == 1, ""); -#else _Static_assert(__GCC_ATOMIC_LLONG_LOCK_FREE == 2, ""); -#endif _Static_assert(__GCC_ATOMIC_LLONG_LOCK_FREE == __CLANG_ATOMIC_LLONG_LOCK_FREE, ""); _Static_assert(__GCC_ATOMIC_POINTER_LOCK_FREE == 2, ""); _Static_assert(__GCC_ATOMIC_POINTER_LOCK_FREE == __CLANG_ATOMIC_POINTER_LOCK_FREE, ""); -- cgit v1.2.3-65-gdbad