mstorsjo created this revision.
mstorsjo added reviewers: compnerd, rnk, majnemer.
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.
Repository:
rC Clang
https://reviews.llvm.org/D43734
Files:
lib/AST/RecordLayoutBuilder.cpp
test/CodeGen/mingw-long-double.c
Index: test/CodeGen/mingw-long-double.c
===================================================================
--- test/CodeGen/mingw-long-double.c
+++ test/CodeGen/mingw-long-double.c
@@ -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 \
Index: lib/AST/RecordLayoutBuilder.cpp
===================================================================
--- lib/AST/RecordLayoutBuilder.cpp
+++ lib/AST/RecordLayoutBuilder.cpp
@@ -1752,7 +1752,8 @@
QualType T = Context.getBaseElementType(D->getType());
if (const BuiltinType *BTy = T->getAs<BuiltinType>()) {
CharUnits TypeSize = Context.getTypeSizeInChars(BTy);
- if (TypeSize > FieldAlign)
+ if (TypeSize > FieldAlign &&
+ llvm::isPowerOf2_64(TypeSize.getQuantity()))
FieldAlign = TypeSize;
}
}
Index: test/CodeGen/mingw-long-double.c
===================================================================
--- test/CodeGen/mingw-long-double.c
+++ test/CodeGen/mingw-long-double.c
@@ -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 \
Index: lib/AST/RecordLayoutBuilder.cpp
===================================================================
--- lib/AST/RecordLayoutBuilder.cpp
+++ lib/AST/RecordLayoutBuilder.cpp
@@ -1752,7 +1752,8 @@
QualType T = Context.getBaseElementType(D->getType());
if (const BuiltinType *BTy = T->getAs<BuiltinType>()) {
CharUnits TypeSize = Context.getTypeSizeInChars(BTy);
- if (TypeSize > FieldAlign)
+ if (TypeSize > FieldAlign &&
+ llvm::isPowerOf2_64(TypeSize.getQuantity()))
FieldAlign = TypeSize;
}
}
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