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Teach getCastOpcode about element-by-element vector casts. For example, "trunc"

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can be used to turn a <4 x i64> into a <4 x i32> but getCastOpcode would assert
if you passed these types to it.  Note that this strictly extends the previous
functionality: if getCastOpcode previously accepted two vector types (i.e. didn't
assert) then it still will and returns the same opcode (BitCast).  That's because
before it would only accept vectors with the same bitwidth, and the new code only
touches vectors with the same length.  However if two vectors have both the same
bitwidth and the same length then their element types have the same bitwidth, so
the new logic will return BitCast as before.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131530 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Duncan Sands 2011-05-18 07:13:41 +00:00
parent 2a8eb722c7
commit 117feba971
2 changed files with 33 additions and 4 deletions
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29
lib/VMCore/Instructions.cpp
View File

@ -2254,6 +2254,14 @@ bool CastInst::isCastable(const Type *SrcTy, const Type *DestTy) {
if (SrcTy == DestTy)
return true;
if (const VectorType *SrcVecTy = dyn_cast<VectorType>(SrcTy))
if (const VectorType *DestVecTy = dyn_cast<VectorType>(DestTy))
if (SrcVecTy->getNumElements() == DestVecTy->getNumElements()) {
// An element by element cast. Valid if casting the elements is valid.
SrcTy = SrcVecTy->getElementType();
DestTy = DestVecTy->getElementType();
}
// Get the bit sizes, we'll need these
unsigned SrcBits = SrcTy->getScalarSizeInBits(); // 0 for ptr
unsigned DestBits = DestTy->getScalarSizeInBits(); // 0 for ptr
@ -2322,14 +2330,27 @@ bool CastInst::isCastable(const Type *SrcTy, const Type *DestTy) {
Instruction::CastOps
CastInst::getCastOpcode(
const Value *Src, bool SrcIsSigned, const Type *DestTy, bool DestIsSigned) {
// Get the bit sizes, we'll need these
const Type *SrcTy = Src->getType();
unsigned SrcBits = SrcTy->getScalarSizeInBits(); // 0 for ptr
unsigned DestBits = DestTy->getScalarSizeInBits(); // 0 for ptr
assert(SrcTy->isFirstClassType() && DestTy->isFirstClassType() &&
"Only first class types are castable!");
if (SrcTy == DestTy)
return BitCast;
if (const VectorType *SrcVecTy = dyn_cast<VectorType>(SrcTy))
if (const VectorType *DestVecTy = dyn_cast<VectorType>(DestTy))
if (SrcVecTy->getNumElements() == DestVecTy->getNumElements()) {
// An element by element cast. Find the appropriate opcode based on the
// element types.
SrcTy = SrcVecTy->getElementType();
DestTy = DestVecTy->getElementType();
}
// Get the bit sizes, we'll need these
unsigned SrcBits = SrcTy->getScalarSizeInBits(); // 0 for ptr
unsigned DestBits = DestTy->getScalarSizeInBits(); // 0 for ptr
// Run through the possibilities ...
if (DestTy->isIntegerTy()) { // Casting to integral
if (SrcTy->isIntegerTy()) { // Casting from integral
@ -2384,7 +2405,7 @@ CastInst::getCastOpcode(
if (const VectorType *SrcPTy = dyn_cast<VectorType>(SrcTy)) {
assert(DestPTy->getBitWidth() == SrcPTy->getBitWidth() &&
"Casting vector to vector of different widths");
SrcPTy = NULL;
(void)SrcPTy;
return BitCast; // vector -> vector
} else if (DestPTy->getBitWidth() == SrcBits) {
return BitCast; // float/int -> vector

8
unittests/VMCore/InstructionsTest.cpp
View File

@ -114,11 +114,19 @@ TEST(InstructionsTest, CastInst) {
const Type* Int8Ty = Type::getInt8Ty(C);
const Type* Int64Ty = Type::getInt64Ty(C);
const Type* V8x8Ty = VectorType::get(Int8Ty, 8);
const Type* V8x64Ty = VectorType::get(Int64Ty, 8);
const Type* X86MMXTy = Type::getX86_MMXTy(C);
const Constant* c8 = Constant::getNullValue(V8x8Ty);
const Constant* c64 = Constant::getNullValue(V8x64Ty);
EXPECT_TRUE(CastInst::isCastable(V8x8Ty, X86MMXTy));
EXPECT_TRUE(CastInst::isCastable(X86MMXTy, V8x8Ty));
EXPECT_FALSE(CastInst::isCastable(Int64Ty, X86MMXTy));
EXPECT_TRUE(CastInst::isCastable(V8x64Ty, V8x8Ty));
EXPECT_TRUE(CastInst::isCastable(V8x8Ty, V8x64Ty));
EXPECT_EQ(CastInst::getCastOpcode(c64, true, V8x8Ty, true), CastInst::Trunc);
EXPECT_EQ(CastInst::getCastOpcode(c8, true, V8x64Ty, true), CastInst::SExt);
}
} // end anonymous namespace