6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-01-26 23:32:58 +00:00
Code Issues Projects Releases Wiki Activity

Fixes following the CR by Chris and Duncan:

Browse Source 
Optimize chained bitcasts of the form A->B->A.
Undo r138722 and change isEliminableCastPair to allow this case.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@138756 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nadav Rotem 2011-08-29 19:58:36 +00:00
parent 0da10cf44d
commit 89879ec76b
4 changed files with 47 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
lib/Analysis/ConstantFolding.cpp
View File

@ -51,12 +51,6 @@ static Constant *FoldBitCast(Constant *C, Type *DestTy,
if (C->isAllOnesValue() && !DestTy->isX86_MMXTy())
return Constant::getAllOnesValue(DestTy);
// Bitcast of Bitcast can be done using a single cast.
ConstantExpr *CE = dyn_cast<ConstantExpr>(C);
if (CE && CE->getOpcode() == Instruction::BitCast) {
return ConstantExpr::getBitCast(CE->getOperand(0), DestTy);
}
// The code below only handles casts to vectors currently.
VectorType *DestVTy = dyn_cast<VectorType>(DestTy);
if (DestVTy == 0)

5
lib/Transforms/InstCombine/InstCombineCasts.cpp
View File

@ -1659,11 +1659,6 @@ Instruction *InstCombiner::visitBitCast(BitCastInst &CI) {
if (DestTy == Src->getType())
return ReplaceInstUsesWith(CI, Src);
// Bitcasts are transitive.
if (BitCastInst* BSrc = dyn_cast<BitCastInst>(Src)) {
return CastInst::Create(Instruction::BitCast, BSrc->getOperand(0), DestTy);
}
if (PointerType *DstPTy = dyn_cast<PointerType>(DestTy)) {
PointerType *SrcPTy = cast<PointerType>(SrcTy);
Type *DstElTy = DstPTy->getElementType();

19
lib/VMCore/Instructions.cpp
View File

@ -2059,8 +2059,7 @@ bool CastInst::isNoopCast(Type *IntPtrTy) const {
/// If no such cast is permited, the function returns 0.
unsigned CastInst::isEliminableCastPair(
Instruction::CastOps firstOp, Instruction::CastOps secondOp,
Type *SrcTy, Type *MidTy, Type *DstTy, Type *IntPtrTy)
{
Type *SrcTy, Type *MidTy, Type *DstTy, Type *IntPtrTy) {
// Define the 144 possibilities for these two cast instructions. The values
// in this matrix determine what to do in a given situation and select the
// case in the switch below. The rows correspond to firstOp, the columns
@ -2113,12 +2112,16 @@ unsigned CastInst::isEliminableCastPair(
};
// If either of the casts are a bitcast from scalar to vector, disallow the
// merging.
if ((firstOp == Instruction::BitCast &&
isa<VectorType>(SrcTy) != isa<VectorType>(MidTy)) ||
(secondOp == Instruction::BitCast &&
isa<VectorType>(MidTy) != isa<VectorType>(DstTy)))
return 0; // Disallowed
// merging. However, bitcast of A->B->A are allowed.
bool isFirstBitcast = (firstOp == Instruction::BitCast);
bool isSecondBitcast = (secondOp == Instruction::BitCast);
bool chainedBitcast = (SrcTy == DstTy && isFirstBitcast && isSecondBitcast);
// Check if any of the bitcasts convert scalars<->vectors.
if ((isFirstBitcast && isa<VectorType>(SrcTy) != isa<VectorType>(MidTy)) ||
(isSecondBitcast && isa<VectorType>(MidTy) != isa<VectorType>(DstTy)))
// Unless we are bitcasing to the original type, disallow optimizations.
if (!chainedBitcast) return 0;
int ElimCase = CastResults[firstOp-Instruction::CastOpsBegin]
[secondOp-Instruction::CastOpsBegin];

39
test/Transforms/InstCombine/cast.ll
View File

@ -632,15 +632,48 @@ entry:
define <4 x float> @test64(<4 x float> %c) nounwind {
%t0 = bitcast <4 x float> %c to <4 x i32>
%t1 = bitcast <4 x i32> %t0 to <2 x double>
%t2 = bitcast <2 x double> %t1 to <4 x float>
ret <4 x float> %t2
%t1 = bitcast <4 x i32> %t0 to <4 x float>
ret <4 x float> %t1
; CHECK: @test64
; CHECK-NEXT: ret <4 x float> %c
}
define <4 x float> @test65(<4 x float> %c) nounwind {
%t0 = bitcast <4 x float> %c to <2 x double>
%t1 = bitcast <2 x double> %t0 to <4 x float>
ret <4 x float> %t1
; CHECK: @test65
; CHECK-NEXT: ret <4 x float> %c
}
define <2 x float> @test66(<2 x float> %c) nounwind {
%t0 = bitcast <2 x float> %c to double
%t1 = bitcast double %t0 to <2 x float>
ret <2 x float> %t1
; CHECK: @test66
; CHECK-NEXT: ret <2 x float> %c
}
define float @test2c() {
ret float extractelement (<2 x float> bitcast (double bitcast (<2 x float> <float -1.000000e+00, float -1.000000e+00> to double) to <2 x float>), i32 0)
; CHECK: @test2c
; CHECK-NOT: extractelement
}
define i64 @test_mmx(<2 x i32> %c) nounwind {
%A = bitcast <2 x i32> %c to x86_mmx
%B = bitcast x86_mmx %A to <2 x i32>
%C = bitcast <2 x i32> %B to i64
ret i64 %C
; CHECK: @test_mmx
; CHECK-NOT: x86_mmx
}
define i64 @test_mmx_const(<2 x i32> %c) nounwind {
%A = bitcast <2 x i32> zeroinitializer to x86_mmx
%B = bitcast x86_mmx %A to <2 x i32>
%C = bitcast <2 x i32> %B to i64
ret i64 %C
; CHECK: @test_mmx_const
; CHECK-NOT: x86_mmx
}