[llvm-commits] [llvm] r138756 - in /llvm/trunk: lib/Analysis/ConstantFolding.cpp lib/Transforms/InstCombine/InstCombineCasts.cpp lib/VMCore/Instructions.cpp test/Transforms/InstCombine/cast.ll
Nadav Rotem
nadav.rotem at intel.com
Mon Aug 29 12:58:37 PDT 2011
Author: nadav
Date: Mon Aug 29 14:58:36 2011
New Revision: 138756
URL: http://llvm.org/viewvc/llvm-project?rev=138756&view=rev
Log:
Fixes following the CR by Chris and Duncan:
Optimize chained bitcasts of the form A->B->A.
Undo r138722 and change isEliminableCastPair to allow this case.
Modified:
llvm/trunk/lib/Analysis/ConstantFolding.cpp
llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp
llvm/trunk/lib/VMCore/Instructions.cpp
llvm/trunk/test/Transforms/InstCombine/cast.ll
Modified: llvm/trunk/lib/Analysis/ConstantFolding.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ConstantFolding.cpp?rev=138756&r1=138755&r2=138756&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ConstantFolding.cpp (original)
+++ llvm/trunk/lib/Analysis/ConstantFolding.cpp Mon Aug 29 14:58:36 2011
@@ -51,12 +51,6 @@
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)
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp?rev=138756&r1=138755&r2=138756&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp Mon Aug 29 14:58:36 2011
@@ -1659,11 +1659,6 @@
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();
Modified: llvm/trunk/lib/VMCore/Instructions.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/VMCore/Instructions.cpp?rev=138756&r1=138755&r2=138756&view=diff
==============================================================================
--- llvm/trunk/lib/VMCore/Instructions.cpp (original)
+++ llvm/trunk/lib/VMCore/Instructions.cpp Mon Aug 29 14:58:36 2011
@@ -2059,8 +2059,7 @@
/// 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 @@
};
// 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];
Modified: llvm/trunk/test/Transforms/InstCombine/cast.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/cast.ll?rev=138756&r1=138755&r2=138756&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/cast.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/cast.ll Mon Aug 29 14:58:36 2011
@@ -632,15 +632,48 @@
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
+}
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