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[mips] Handle transparent unions correctly. 

Summary:
This fixes MultiSource/Applications/lemon on big-endian N32 by correcting the
handling of the argument to wait(). glibc defines it as a transparent union of
void* and int*. Such unions are passed according to the rules of the first
member so the argument must be passed as if it were a void* (sign extended from
i32 to i64) and not as a union (shifted to the upper bits of an i64).

wait() already behaves correctly on big-endian O32 and N64 since the union is
already the same size as an argument slot.

Reviewers: atanasyan

Reviewed By: atanasyan

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D6963

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@225981 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Daniel Sanders 2015-01-14 12:00:12 +00:00
parent 6c1b926674
commit e90c8e8c4e
2 changed files with 29 additions and 0 deletions
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2
lib/CodeGen/TargetInfo.cpp
View File

@ -5693,6 +5693,8 @@ llvm::Type *MipsABIInfo::getPaddingType(uint64_t OrigOffset,
ABIArgInfo
MipsABIInfo::classifyArgumentType(QualType Ty, uint64_t &Offset) const {
Ty = useFirstFieldIfTransparentUnion(Ty);
uint64_t OrigOffset = Offset;
uint64_t TySize = getContext().getTypeSize(Ty);
uint64_t Align = getContext().getTypeAlign(Ty) / 8;

27
test/CodeGen/mips-transparent-union.c Normal file
View File

@ -0,0 +1,27 @@
// RUN: %clang_cc1 -triple mips64-linux-gnu -S -o - -emit-llvm %s | FileCheck %s
//
// Transparent unions are passed according to the calling convention rules of
// the first member. In this case, it is as if it were a void pointer so we
// do not have the inreg attribute we would normally have for unions.
//
// This comes up in glibc's wait() function and matters for the big-endian N32
// case where pointers are promoted to i64 and a non-transparent union would be
// passed in the upper 32-bits of an i64.
union either_pointer {
void *void_ptr;
int *int_ptr;
} __attribute__((transparent_union));
extern void foo(union either_pointer p);
int data;
void bar(void) {
return foo(&data);
}
// CHECK-LABEL: define void @bar()
// CHECK: call void @foo(i8* %{{[0-9]+}})
// CHECK: declare void @foo(i8*)