From b7c6d95af5e295c560d1445e7090e31eb9289932 Mon Sep 17 00:00:00 2001 From: Tom Tan Date: Thu, 2 May 2019 00:38:14 +0000 Subject: [PATCH] [COFF, ARM64] Align global symbol by size for ARM64 MSVC ABI According to alignment section in below ARM64 ABI document, MSVC could increase alignment of global data based on its total size. Clang doesn't do this. Compile the same symbol into different alignments by Clang and MSVC could cause link error because some instruction encodings, like 64-bit LDR/STR with immediate, require the target to be 8 bytes aligned, and linker could choose code stream with such LDR/STR instruction from MSVC and 4 bytes aligned data from Clang into final image, which actually cannot be linked together (see https://bugs.llvm.org/show_bug.cgi?id=41506 for more details). https://docs.microsoft.com/en-us/cpp/build/arm64-windows-abi-conventions?view=vs-2019#alignment Differential Revision: https://reviews.llvm.org/D61225 llvm-svn: 359744 --- clang/include/clang/Basic/TargetInfo.h | 4 ++- clang/lib/AST/ASTContext.cpp | 9 ++++--- clang/lib/Basic/Targets/AArch64.cpp | 17 ++++++++++++ clang/lib/Basic/Targets/AArch64.h | 2 ++ clang/lib/Basic/Targets/NVPTX.cpp | 2 +- .../CodeGen/arm64-microsoft-struct-align.cpp | 27 +++++++++++++++++++ 6 files changed, 56 insertions(+), 5 deletions(-) create mode 100644 clang/test/CodeGen/arm64-microsoft-struct-align.cpp diff --git a/clang/include/clang/Basic/TargetInfo.h b/clang/include/clang/Basic/TargetInfo.h index 7b9f9d9565d06..9143431c442ee 100644 --- a/clang/include/clang/Basic/TargetInfo.h +++ b/clang/include/clang/Basic/TargetInfo.h @@ -542,7 +542,9 @@ class TargetInfo : public virtual TransferrableTargetInfo, /// getMinGlobalAlign - Return the minimum alignment of a global variable, /// unless its alignment is explicitly reduced via attributes. - unsigned getMinGlobalAlign() const { return MinGlobalAlign; } + virtual unsigned getMinGlobalAlign (uint64_t) const { + return MinGlobalAlign; + } /// Return the largest alignment for which a suitably-sized allocation with /// '::operator new(size_t)' is guaranteed to produce a correctly-aligned diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp index ef0244ace08f6..ad76e529bde82 100644 --- a/clang/lib/AST/ASTContext.cpp +++ b/clang/lib/AST/ASTContext.cpp @@ -1600,8 +1600,10 @@ CharUnits ASTContext::getDeclAlign(const Decl *D, bool ForAlignof) const { if (BaseT.getQualifiers().hasUnaligned()) Align = Target->getCharWidth(); if (const auto *VD = dyn_cast(D)) { - if (VD->hasGlobalStorage() && !ForAlignof) - Align = std::max(Align, getTargetInfo().getMinGlobalAlign()); + if (VD->hasGlobalStorage() && !ForAlignof) { + uint64_t TypeSize = getTypeSize(T.getTypePtr()); + Align = std::max(Align, getTargetInfo().getMinGlobalAlign(TypeSize)); + } } } @@ -2239,7 +2241,8 @@ unsigned ASTContext::getTargetDefaultAlignForAttributeAligned() const { /// getAlignOfGlobalVar - Return the alignment in bits that should be given /// to a global variable of the specified type. unsigned ASTContext::getAlignOfGlobalVar(QualType T) const { - return std::max(getTypeAlign(T), getTargetInfo().getMinGlobalAlign()); + uint64_t TypeSize = getTypeSize(T.getTypePtr()); + return std::max(getTypeAlign(T), getTargetInfo().getMinGlobalAlign(TypeSize)); } /// getAlignOfGlobalVarInChars - Return the alignment in characters that diff --git a/clang/lib/Basic/Targets/AArch64.cpp b/clang/lib/Basic/Targets/AArch64.cpp index d61a6f4938b2e..120a0e2d4e884 100644 --- a/clang/lib/Basic/Targets/AArch64.cpp +++ b/clang/lib/Basic/Targets/AArch64.cpp @@ -551,6 +551,23 @@ MicrosoftARM64TargetInfo::getCallingConvKind(bool ClangABICompat4) const { return CCK_MicrosoftWin64; } +unsigned MicrosoftARM64TargetInfo::getMinGlobalAlign(uint64_t TypeSize) const { + unsigned Align = WindowsARM64TargetInfo::getMinGlobalAlign(TypeSize); + + // MSVC does size based alignment for arm64 based on alignment section in + // below document, replicate that to keep alignment consistent with object + // files compiled by MSVC. + // https://docs.microsoft.com/en-us/cpp/build/arm64-windows-abi-conventions + if (TypeSize >= 512) { // TypeSize >= 64 bytes + Align = std::max(Align, 128u); // align type at least 16 bytes + } else if (TypeSize >= 64) { // TypeSize >= 8 bytes + Align = std::max(Align, 64u); // align type at least 8 butes + } else if (TypeSize >= 16) { // TypeSize >= 2 bytes + Align = std::max(Align, 32u); // align type at least 4 bytes + } + return Align; +} + MinGWARM64TargetInfo::MinGWARM64TargetInfo(const llvm::Triple &Triple, const TargetOptions &Opts) : WindowsARM64TargetInfo(Triple, Opts) { diff --git a/clang/lib/Basic/Targets/AArch64.h b/clang/lib/Basic/Targets/AArch64.h index f843a9ce74b41..73fd3bde5adcf 100644 --- a/clang/lib/Basic/Targets/AArch64.h +++ b/clang/lib/Basic/Targets/AArch64.h @@ -129,6 +129,8 @@ class LLVM_LIBRARY_VISIBILITY MicrosoftARM64TargetInfo MacroBuilder &Builder) const override; TargetInfo::CallingConvKind getCallingConvKind(bool ClangABICompat4) const override; + + unsigned getMinGlobalAlign(uint64_t TypeSize) const override; }; // ARM64 MinGW target diff --git a/clang/lib/Basic/Targets/NVPTX.cpp b/clang/lib/Basic/Targets/NVPTX.cpp index ee4eb898a10b1..c917e3d41985e 100644 --- a/clang/lib/Basic/Targets/NVPTX.cpp +++ b/clang/lib/Basic/Targets/NVPTX.cpp @@ -119,7 +119,7 @@ NVPTXTargetInfo::NVPTXTargetInfo(const llvm::Triple &Triple, LongAlign = HostTarget->getLongAlign(); LongLongWidth = HostTarget->getLongLongWidth(); LongLongAlign = HostTarget->getLongLongAlign(); - MinGlobalAlign = HostTarget->getMinGlobalAlign(); + MinGlobalAlign = HostTarget->getMinGlobalAlign(/* TypeSize = */ 0); NewAlign = HostTarget->getNewAlign(); DefaultAlignForAttributeAligned = HostTarget->getDefaultAlignForAttributeAligned(); diff --git a/clang/test/CodeGen/arm64-microsoft-struct-align.cpp b/clang/test/CodeGen/arm64-microsoft-struct-align.cpp new file mode 100644 index 0000000000000..4076c3ca34ad7 --- /dev/null +++ b/clang/test/CodeGen/arm64-microsoft-struct-align.cpp @@ -0,0 +1,27 @@ +// RUN: %clang_cc1 -triple aarch64-windows -ffreestanding -emit-llvm -O0 \ +// RUN: -x c++ -o - %s | FileCheck %s + +struct size1 { char str[1]; }; +struct size2 { char str[2]; }; +struct size7 { char str[4]; }; +struct size8 { char str[8]; }; +struct size63 { char str[63]; }; +struct size64 { char str[64]; }; + +struct size1 s1; +// CHECK: @"?s1@@3Usize1@@A" = dso_local global %struct.size1 zeroinitializer, align 1 + +struct size2 s2; +// CHECK: @"?s2@@3Usize2@@A" = dso_local global %struct.size2 zeroinitializer, align 4 + +struct size7 s7; +// CHECK: @"?s7@@3Usize7@@A" = dso_local global %struct.size7 zeroinitializer, align 4 + +struct size8 s8; +// CHECK: @"?s8@@3Usize8@@A" = dso_local global %struct.size8 zeroinitializer, align 8 + +struct size63 s63; +// CHECK: @"?s63@@3Usize63@@A" = dso_local global %struct.size63 zeroinitializer, align 8 + +struct size64 s64; +// CHECK: @"?s64@@3Usize64@@A" = dso_local global %struct.size64 zeroinitializer, align 16