diff options
-rw-r--r-- | lib/Analysis/ConstantFolding.cpp | 6 | ||||
-rw-r--r-- | lib/Transforms/InstCombine/InstCombineCasts.cpp | 5 | ||||
-rw-r--r-- | lib/VMCore/Instructions.cpp | 19 | ||||
-rw-r--r-- | test/Transforms/InstCombine/cast.ll | 39 |
4 files changed, 47 insertions, 22 deletions
diff --git a/lib/Analysis/ConstantFolding.cpp b/lib/Analysis/ConstantFolding.cpp index 613804d6d2..df79849c3c 100644 --- a/lib/Analysis/ConstantFolding.cpp +++ b/lib/Analysis/ConstantFolding.cpp @@ -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) diff --git a/lib/Transforms/InstCombine/InstCombineCasts.cpp b/lib/Transforms/InstCombine/InstCombineCasts.cpp index 6c42c0c660..ba90bf6b5c 100644 --- a/lib/Transforms/InstCombine/InstCombineCasts.cpp +++ b/lib/Transforms/InstCombine/InstCombineCasts.cpp @@ -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(); diff --git a/lib/VMCore/Instructions.cpp b/lib/VMCore/Instructions.cpp index 2f6c069a2d..908e19e2ab 100644 --- a/lib/VMCore/Instructions.cpp +++ b/lib/VMCore/Instructions.cpp @@ -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]; diff --git a/test/Transforms/InstCombine/cast.ll b/test/Transforms/InstCombine/cast.ll index 06cdae24b4..19d5a0ae77 100644 --- a/test/Transforms/InstCombine/cast.ll +++ b/test/Transforms/InstCombine/cast.ll @@ -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 +} |