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InstCombine: Fold bitcast of vector to FP scalar

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llvm-svn: 288978
This commit is contained in:
Matt Arsenault 2016-12-07 20:56:11 +00:00
parent 98f9dd59fb
commit 61527cb46b
2 changed files with 89 additions and 23 deletions
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48
lib/Analysis/ConstantFolding.cpp
View File

@ -88,7 +88,7 @@ static Constant *foldConstVectorToAPInt(APInt &Result, Type *DestTy,
return nullptr;
}
// Constant fold bitcast, symbolically evaluating it with DataLayout.
/// Constant fold bitcast, symbolically evaluating it with DataLayout.
/// This always returns a non-null constant, but it may be a
/// ConstantExpr if unfoldable.
Constant *FoldBitCast(Constant *C, Type *DestTy, const DataLayout &DL) {
@ -99,31 +99,33 @@ Constant *FoldBitCast(Constant *C, Type *DestTy, const DataLayout &DL) {
!DestTy->isPtrOrPtrVectorTy()) // Don't get ones for ptr types!
return Constant::getAllOnesValue(DestTy);
// Handle a vector->integer cast.
if (auto *IT = dyn_cast<IntegerType>(DestTy)) {
auto *VTy = dyn_cast<VectorType>(C->getType());
if (!VTy)
return ConstantExpr::getBitCast(C, DestTy);
if (auto *VTy = dyn_cast<VectorType>(C->getType())) {
// Handle a vector->scalar integer/fp cast.
if (isa<IntegerType>(DestTy) || DestTy->isFloatingPointTy()) {
unsigned NumSrcElts = VTy->getNumElements();
Type *SrcEltTy = VTy->getElementType();
unsigned NumSrcElts = VTy->getNumElements();
Type *SrcEltTy = VTy->getElementType();
// If the vector is a vector of floating point, convert it to vector of int
// to simplify things.
if (SrcEltTy->isFloatingPointTy()) {
unsigned FPWidth = SrcEltTy->getPrimitiveSizeInBits();
Type *SrcIVTy =
VectorType::get(IntegerType::get(C->getContext(), FPWidth), NumSrcElts);
// Ask IR to do the conversion now that #elts line up.
C = ConstantExpr::getBitCast(C, SrcIVTy);
}
// If the vector is a vector of floating point, convert it to vector of int
// to simplify things.
if (SrcEltTy->isFloatingPointTy()) {
unsigned FPWidth = SrcEltTy->getPrimitiveSizeInBits();
Type *SrcIVTy =
VectorType::get(IntegerType::get(C->getContext(), FPWidth), NumSrcElts);
// Ask IR to do the conversion now that #elts line up.
C = ConstantExpr::getBitCast(C, SrcIVTy);
APInt Result(DL.getTypeSizeInBits(DestTy), 0);
if (Constant *CE = foldConstVectorToAPInt(Result, DestTy, C,
SrcEltTy, NumSrcElts, DL))
return CE;
if (isa<IntegerType>(DestTy))
return ConstantInt::get(DestTy, Result);
APFloat FP(DestTy->getFltSemantics(), Result);
return ConstantFP::get(DestTy->getContext(), FP);
}
APInt Result(IT->getBitWidth(), 0);
if (Constant *CE = foldConstVectorToAPInt(Result, DestTy, C,
SrcEltTy, NumSrcElts, DL))
return CE;
return ConstantInt::get(IT, Result);
}
// The code below only handles casts to vectors currently.

64
test/Transforms/InstCombine/bitcast.ll
View File

@ -449,3 +449,67 @@ define i8 @test8() {
%res = bitcast <8 x i1> <i1 true, i1 true, i1 false, i1 true, i1 false, i1 true, i1 false, i1 true> to i8
ret i8 %res
}
@g = internal unnamed_addr global i32 undef
; CHECK-LABEL: @constant_fold_vector_to_double(
; CHECK: store volatile double 1.000000e+00,
; CHECK: store volatile double 1.000000e+00,
; CHECK: store volatile double 1.000000e+00,
; CHECK: store volatile double 1.000000e+00,
; CHECK: store volatile double 0xFFFFFFFFFFFFFFFF,
; CHECK: store volatile double 0x162E000004D2,
; CHECK: store volatile double bitcast (<2 x i32> <i32 1234, i32 ptrtoint (i32* @g to i32)> to double),
; CHECK: store volatile double 0x400000003F800000,
; CHECK: store volatile double 0.000000e+00,
; CHECK: store volatile double 0.000000e+00,
; CHECK: store volatile double 0.000000e+00,
; CHECK: store volatile double 0.000000e+00,
; CHECK: store volatile double 0.000000e+00,
; CHECK: store volatile double 0.000000e+00,
define void @constant_fold_vector_to_double() {
store volatile double bitcast (<1 x i64> <i64 4607182418800017408> to double), double* undef
store volatile double bitcast (<2 x i32> <i32 0, i32 1072693248> to double), double* undef
store volatile double bitcast (<4 x i16> <i16 0, i16 0, i16 0, i16 16368> to double), double* undef
store volatile double bitcast (<8 x i8> <i8 0, i8 0, i8 0, i8 0, i8 0, i8 0, i8 240, i8 63> to double), double* undef
store volatile double bitcast (<2 x i32> <i32 -1, i32 -1> to double), double* undef
store volatile double bitcast (<2 x i32> <i32 1234, i32 5678> to double), double* undef
store volatile double bitcast (<2 x i32> <i32 1234, i32 ptrtoint (i32* @g to i32)> to double), double* undef
store volatile double bitcast (<2 x float> <float 1.0, float 2.0> to double), double* undef
store volatile double bitcast (<2 x i32> zeroinitializer to double), double* undef
store volatile double bitcast (<4 x i16> zeroinitializer to double), double* undef
store volatile double bitcast (<8 x i8> zeroinitializer to double), double* undef
store volatile double bitcast (<16 x i4> zeroinitializer to double), double* undef
store volatile double bitcast (<32 x i2> zeroinitializer to double), double* undef
store volatile double bitcast (<64 x i1> zeroinitializer to double), double* undef
ret void
}
; CHECK-LABEL: @constant_fold_vector_to_float(
; CHECK: store volatile float 1.000000e+00,
; CHECK: store volatile float 1.000000e+00,
; CHECK: store volatile float 1.000000e+00,
; CHECK: store volatile float 1.000000e+00,
define void @constant_fold_vector_to_float() {
store volatile float bitcast (<1 x i32> <i32 1065353216> to float), float* undef
store volatile float bitcast (<2 x i16> <i16 0, i16 16256> to float), float* undef
store volatile float bitcast (<4 x i8> <i8 0, i8 0, i8 128, i8 63> to float), float* undef
store volatile float bitcast (<32 x i1> <i1 0, i1 0, i1 0, i1 0, i1 0, i1 0, i1 0, i1 0, i1 0, i1 0, i1 0, i1 0, i1 0, i1 0, i1 0, i1 0, i1 0, i1 0, i1 0, i1 0, i1 0, i1 0, i1 0, i1 1, i1 1, i1 1, i1 1, i1 1, i1 1, i1 1, i1 0, i1 0> to float), float* undef
ret void
}
; CHECK-LABEL: @constant_fold_vector_to_half(
; CHECK: store volatile half 0xH4000,
; CHECK: store volatile half 0xH4000,
define void @constant_fold_vector_to_half() {
store volatile half bitcast (<2 x i8> <i8 0, i8 64> to half), half* undef
store volatile half bitcast (<4 x i4> <i4 0, i4 0, i4 0, i4 4> to half), half* undef
ret void
}