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authorChris Lattner <sabre@nondot.org>2010-08-26 21:55:42 +0000
committerChris Lattner <sabre@nondot.org>2010-08-26 21:55:42 +0000
commite5a1426174986951a20ec6ffd119b77a24a65706 (patch)
tree99c5869da3d33eace7a8e473ac7333819a0aa805 /lib/Transforms
parenta6140a14444da1aa104f6ab7c40c5c920552f474 (diff)
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optimize bitcast(trunc(bitcast(x))) where the result is a float and 'x'
is a vector to be a vector element extraction. This allows clang to compile: struct S { float A, B, C, D; }; float foo(struct S A) { return A.A + A.B+A.C+A.D; } into: _foo: ## @foo ## BB#0: ## %entry movd %xmm0, %rax shrq $32, %rax movd %eax, %xmm2 addss %xmm0, %xmm2 movapd %xmm1, %xmm3 addss %xmm2, %xmm3 movd %xmm1, %rax shrq $32, %rax movd %eax, %xmm0 addss %xmm3, %xmm0 ret instead of: _foo: ## @foo ## BB#0: ## %entry movd %xmm0, %rax movd %eax, %xmm0 shrq $32, %rax movd %eax, %xmm2 addss %xmm0, %xmm2 movd %xmm1, %rax movd %eax, %xmm1 addss %xmm2, %xmm1 shrq $32, %rax movd %eax, %xmm0 addss %xmm1, %xmm0 ret ... eliminating half of the horribleness. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112227 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Transforms')
-rw-r--r--lib/Transforms/InstCombine/InstCombineCasts.cpp34
1 files changed, 34 insertions, 0 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineCasts.cpp b/lib/Transforms/InstCombine/InstCombineCasts.cpp
index dbe5200..ef5bbc4 100644
--- a/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -1335,6 +1335,35 @@ static Instruction *OptimizeVectorResize(Value *InVal, const VectorType *DestTy,
return new ShuffleVectorInst(InVal, V2, Mask);
}
+/// OptimizeIntToFloatBitCast - See if we can optimize an integer->float/double
+/// bitcast. The various long double bitcasts can't get in here.
+static Instruction *OptimizeIntToFloatBitCast(BitCastInst &CI,InstCombiner &IC) {
+ Value *Src = CI.getOperand(0);
+
+ // If this is a bitcast from int to float, check to see if the int is an
+ // extraction from a vector.
+ Value *VecInput = 0;
+ if (match(Src, m_Trunc(m_BitCast(m_Value(VecInput)))) &&
+ isa<VectorType>(VecInput->getType())) {
+ const VectorType *VecTy = cast<VectorType>(VecInput->getType());
+ const Type *DestTy = CI.getType();
+
+ // If the element type of the vector doesn't match the result type, but the
+ // vector type's size is a multiple of the result type, bitcast it to be a
+ // vector type we can extract from.
+ if (VecTy->getElementType() != DestTy &&
+ VecTy->getPrimitiveSizeInBits() % DestTy->getPrimitiveSizeInBits()==0) {
+ VecTy = VectorType::get(DestTy,
+ VecTy->getPrimitiveSizeInBits() / DestTy->getPrimitiveSizeInBits());
+ VecInput = IC.Builder->CreateBitCast(VecInput, VecTy);
+ }
+
+ if (VecTy->getElementType() == DestTy)
+ return ExtractElementInst::Create(VecInput, IC.Builder->getInt32(0));
+ }
+
+ return 0;
+}
Instruction *InstCombiner::visitBitCast(BitCastInst &CI) {
// If the operands are integer typed then apply the integer transforms,
@@ -1386,6 +1415,11 @@ Instruction *InstCombiner::visitBitCast(BitCastInst &CI) {
((Instruction*)NULL));
}
}
+
+ // Try to optimize int -> float bitcasts.
+ if ((DestTy->isFloatTy() || DestTy->isDoubleTy()) && isa<IntegerType>(SrcTy))
+ if (Instruction *I = OptimizeIntToFloatBitCast(CI, *this))
+ return I;
if (const VectorType *DestVTy = dyn_cast<VectorType>(DestTy)) {
if (DestVTy->getNumElements() == 1 && !SrcTy->isVectorTy()) {