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ignore structs that wrap vectors in IR, the abstraction shouldn't add penalty. 

Before we'd compile the example into something like:

  %coerce.dive2 = getelementptr %struct.v4f32wrapper* %retval, i32 0, i32 0 ; <<4 x float>*> [#uses=1]
  %1 = bitcast <4 x float>* %coerce.dive2 to <2 x double>* ; <<2 x double>*> [#uses=1]
  %2 = load <2 x double>* %1, align 1             ; <<2 x double>> [#uses=1]
  ret <2 x double> %2

Now we produce:

  %coerce.dive2 = getelementptr %struct.v4f32wrapper* %retval, i32 0, i32 0 ; <<4 x float>*> [#uses=1]
  %0 = load <4 x float>* %coerce.dive2, align 1   ; <<4 x float>> [#uses=1]
  ret <4 x float> %0

llvm-svn: 109732
This commit is contained in:
Chris Lattner 2010-07-29 05:02:29 +00:00
parent 4200fe4e50
commit 9fa15c3608
2 changed files with 23 additions and 2 deletions
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15
clang/lib/CodeGen/TargetInfo.cpp
View File

@ -1185,9 +1185,20 @@ ABIArgInfo X86_64ABIInfo::getIndirectResult(QualType Ty) const {
/// full vector XMM register. Pick an LLVM IR type that will be passed as a
/// vector register.
const llvm::Type *X86_64ABIInfo::Get16ByteVectorType(QualType Ty) const {
const llvm::Type *IRType = CGT.ConvertTypeRecursive(Ty);
// Wrapper structs that just contain vectors are passed just like vectors,
// strip them off if present.
const llvm::StructType *STy = dyn_cast<llvm::StructType>(IRType);
while (STy && STy->getNumElements() == 1) {
IRType = STy->getElementType(0);
STy = dyn_cast<llvm::StructType>(IRType);
}
// If the preferred type is a 16-byte vector, prefer to pass it.
if (const llvm::VectorType *VT =
dyn_cast<llvm::VectorType>(CGT.ConvertTypeRecursive(Ty))){
if (const llvm::VectorType *VT = dyn_cast<llvm::VectorType>(IRType)){
const llvm::Type *EltTy = VT->getElementType();
if (VT->getBitWidth() == 128 &&
(EltTy->isFloatTy() || EltTy->isDoubleTy() ||

10
clang/test/CodeGen/x86_64-arguments.c
View File

@ -168,3 +168,13 @@ struct foo26 f26(struct foo26 *P) {
// CHECK: define %struct.foo26 @f26(%struct.foo26* %P)
return *P;
}
struct v4f32wrapper {
v4f32 v;
};
struct v4f32wrapper f27(struct v4f32wrapper X) {
// CHECK: define <4 x float> @f27(<4 x float> %X.coerce)
return X;
}