replica
/
hanchenye-llvm-project
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

[RecordLayout] Don't align to non-power-of-2 sizes when using -mms-bitfields 

When targeting GNU/MinGW for i386, the size of the "long double" data
type is 12 bytes (while it is 8 bytes in MSVC). When building
with -mms-bitfields to have struct layouts match MSVC, data types
are laid out in a struct with alignment according to their size.
However, this doesn't make sense for the long double type, since
it doesn't match MSVC at all, and aligning to a non-power-of-2
size triggers other asserts later.

This matches what GCC does, aligning a long double to 4 bytes
in structs on i386 even when -mms-bitfields is specified.

This fixes asserts when using the max_align_t data type when
building for MinGW/i386 with the -mms-bitfields flag.

Differential Revision: https://reviews.llvm.org/D43734

llvm-svn: 326173
This commit is contained in:
Martin Storsjo 2018-02-27 06:27:06 +00:00
parent 41ffd96445
commit 96b01bcfb6
2 changed files with 8 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
clang/lib/AST/RecordLayoutBuilder.cpp
View File

@ -1752,7 +1752,12 @@ void ItaniumRecordLayoutBuilder::LayoutField(const FieldDecl *D,
QualType T = Context.getBaseElementType(D->getType());
if (const BuiltinType *BTy = T->getAs<BuiltinType>()) {
CharUnits TypeSize = Context.getTypeSizeInChars(BTy);
if (TypeSize > FieldAlign)
assert(
(llvm::isPowerOf2_64(TypeSize.getQuantity()) ||
Context.getTargetInfo().getTriple().isWindowsGNUEnvironment()) &&
"Non PowerOf2 size outside of GNU mode");
if (TypeSize > FieldAlign &&
llvm::isPowerOf2_64(TypeSize.getQuantity()))
FieldAlign = TypeSize;
}
}

2
clang/test/CodeGen/mingw-long-double.c
View File

@ -1,5 +1,7 @@
// RUN: %clang_cc1 -triple i686-windows-gnu -emit-llvm -o - %s \
// RUN: | FileCheck %s --check-prefix=GNU32
// RUN: %clang_cc1 -triple i686-windows-gnu -emit-llvm -o - %s -mms-bitfields \
// RUN: | FileCheck %s --check-prefix=GNU32
// RUN: %clang_cc1 -triple x86_64-windows-gnu -emit-llvm -o - %s \
// RUN: | FileCheck %s --check-prefix=GNU64
// RUN: %clang_cc1 -triple x86_64-windows-msvc -emit-llvm -o - %s \