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now that we have CGT around, we can start using preferred types 

for return values too.  Instead of compiling something like:

struct foo {
  int *X;
  float *Y;
};

struct foo test(struct foo *P) { return *P; }

to:

%1 = type { i64, i64 }

define %1 @test(%struct.foo* %P) nounwind {
entry:
  %retval = alloca %struct.foo, align 8           ; <%struct.foo*> [#uses=2]
  %P.addr = alloca %struct.foo*, align 8          ; <%struct.foo**> [#uses=2]
  store %struct.foo* %P, %struct.foo** %P.addr
  %tmp = load %struct.foo** %P.addr               ; <%struct.foo*> [#uses=1]
  %tmp1 = bitcast %struct.foo* %retval to i8*     ; <i8*> [#uses=1]
  %tmp2 = bitcast %struct.foo* %tmp to i8*        ; <i8*> [#uses=1]
  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %tmp1, i8* %tmp2, i64 16, i32 8, i1 false)
  %0 = bitcast %struct.foo* %retval to %1*        ; <%1*> [#uses=1]
  %1 = load %1* %0, align 1                       ; <%1> [#uses=1]
  ret %1 %1
}

We now get the result more type safe, with:

define %struct.foo @test(%struct.foo* %P) nounwind {
entry:
  %retval = alloca %struct.foo, align 8           ; <%struct.foo*> [#uses=2]
  %P.addr = alloca %struct.foo*, align 8          ; <%struct.foo**> [#uses=2]
  store %struct.foo* %P, %struct.foo** %P.addr
  %tmp = load %struct.foo** %P.addr               ; <%struct.foo*> [#uses=1]
  %tmp1 = bitcast %struct.foo* %retval to i8*     ; <i8*> [#uses=1]
  %tmp2 = bitcast %struct.foo* %tmp to i8*        ; <i8*> [#uses=1]
  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %tmp1, i8* %tmp2, i64 16, i32 8, i1 false)
  %0 = load %struct.foo* %retval                  ; <%struct.foo> [#uses=1]
  ret %struct.foo %0
}

That memcpy is completely terrible, but I don't know how to fix it.

llvm-svn: 109729
This commit is contained in:
Chris Lattner 2010-07-29 04:46:19 +00:00
parent 029c0f1681
commit 3a44c7e55d
3 changed files with 18 additions and 4 deletions
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12
clang/lib/CodeGen/TargetInfo.cpp
View File

@ -1243,6 +1243,7 @@ classifyReturnType(QualType RetTy) const {
assert((Lo != NoClass || Hi == NoClass) && "Invalid null classification.");
assert((Hi != SSEUp || Lo == SSE) && "Invalid SSEUp classification.");
const llvm::Type *IRType = 0;
const llvm::Type *ResType = 0;
switch (Lo) {
case NoClass:
@ -1260,7 +1261,10 @@ classifyReturnType(QualType RetTy) const {
// AMD64-ABI 3.2.3p4: Rule 3. If the class is INTEGER, the next
// available register of the sequence %rax, %rdx is used.
case Integer:
ResType = Get8ByteTypeAtOffset(0, 0, RetTy, 0);
if (IRType == 0)
IRType = CGT.ConvertTypeRecursive(RetTy);
ResType = Get8ByteTypeAtOffset(IRType, 0, RetTy, 0);
break;
// AMD64-ABI 3.2.3p4: Rule 4. If the class is SSE, the next
@ -1299,7 +1303,10 @@ classifyReturnType(QualType RetTy) const {
break;
case Integer: {
const llvm::Type *HiType = Get8ByteTypeAtOffset(0, 8, RetTy, 8);
if (IRType == 0)
IRType = CGT.ConvertTypeRecursive(RetTy);
const llvm::Type *HiType = Get8ByteTypeAtOffset(IRType, 8, RetTy, 8);
ResType = llvm::StructType::get(getVMContext(), ResType, HiType, NULL);
break;
}
@ -1456,7 +1463,6 @@ ABIArgInfo X86_64ABIInfo::classifyArgumentType(QualType Ty, unsigned &neededInt,
void X86_64ABIInfo::computeInfo(CGFunctionInfo &FI) const {
// Pass preferred type into classifyReturnType.
FI.getReturnInfo() = classifyReturnType(FI.getReturnType());
// Keep track of the number of assigned registers.

8
clang/test/CodeGen/x86_64-arguments.c
View File

@ -159,4 +159,12 @@ v4f32 f25(v4f32 X) {
return X+X;
}
struct foo26 {
int *X;
float *Y;
};
struct foo26 f26(struct foo26 *P) {
// CHECK: define %struct.foo26 @f26(%struct.foo26* %P)
return *P;
}

2
clang/test/CodeGenObjC/x86_64-struct-return-gc.m
View File

@ -9,7 +9,7 @@ struct Coerce coerce_func(void);
void Coerce_test(void) {
struct Coerce c;
// CHECK: call i64 @coerce_func
// CHECK: call i8* @coerce_func
// CHECK: call i8* @objc_memmove_collectable(
c = coerce_func();
}