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optimize bitcasts from large integers to vector into vector

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element insertion from the pieces that feed into the vector.
This handles a pattern that occurs frequently due to code
generated for the x86-64 abi.  We now compile something like
this:

struct S { float A, B, C, D; };
struct S g;
struct S bar() { 
  struct S A = g;
  ++A.A;
  ++A.C;
  return A;
}

into all nice vector operations:

_bar:                                   ## @bar
## BB#0:                                ## %entry
	movq	_g@GOTPCREL(%rip), %rax
	movss	LCPI1_0(%rip), %xmm1
	movss	(%rax), %xmm0
	addss	%xmm1, %xmm0
	pshufd	$16, %xmm0, %xmm0
	movss	4(%rax), %xmm2
	movss	12(%rax), %xmm3
	pshufd	$16, %xmm2, %xmm2
	unpcklps	%xmm2, %xmm0
	addss	8(%rax), %xmm1
	pshufd	$16, %xmm1, %xmm1
	pshufd	$16, %xmm3, %xmm2
	unpcklps	%xmm2, %xmm1
	ret

instead of icky integer operations:

_bar:                                   ## @bar
	movq	_g@GOTPCREL(%rip), %rax
	movss	LCPI1_0(%rip), %xmm1
	movss	(%rax), %xmm0
	addss	%xmm1, %xmm0
	movd	%xmm0, %ecx
	movl	4(%rax), %edx
	movl	12(%rax), %esi
	shlq	$32, %rdx
	addq	%rcx, %rdx
	movd	%rdx, %xmm0
	addss	8(%rax), %xmm1
	movd	%xmm1, %eax
	shlq	$32, %rsi
	addq	%rax, %rsi
	movd	%rsi, %xmm1
	ret

This resolves rdar://8360454



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112343 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2010-08-28 01:20:38 +00:00
parent badcda4afa
commit 3dd08734c1
3 changed files with 160 additions and 11 deletions
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136
lib/Transforms/InstCombine/InstCombineCasts.cpp
View File

@ -1362,6 +1362,116 @@ static Instruction *OptimizeVectorResize(Value *InVal, const VectorType *DestTy,
return new ShuffleVectorInst(InVal, V2, Mask);
}
static bool isMultipleOfTypeSize(unsigned Value, const Type *Ty) {
return Value % Ty->getPrimitiveSizeInBits() == 0;
}
static bool getTypeSizeIndex(unsigned Value, const Type *Ty) {
return Value / Ty->getPrimitiveSizeInBits();
}
/// CollectInsertionElements - V is a value which is inserted into a vector of
/// VecEltTy. Look through the value to see if we can decompose it into
/// insertions into the vector. See the example in the comment for
/// OptimizeIntegerToVectorInsertions for the pattern this handles.
/// The type of V is always a non-zero multiple of VecEltTy's size.
///
/// This returns false if the pattern can't be matched or true if it can,
/// filling in Elements with the elements found here.
static bool CollectInsertionElements(Value *V, unsigned ElementIndex,
SmallVectorImpl<Value*> &Elements,
const Type *VecEltTy) {
// If we got down to a value of the right type, we win, try inserting into the
// right element.
if (V->getType() == VecEltTy) {
// Fail if multiple elements are inserted into this slot.
if (ElementIndex >= Elements.size() || Elements[ElementIndex] != 0)
return false;
Elements[ElementIndex] = V;
return true;
}
//if (Constant *C = dyn_cast<Constant>(V)) {
// Figure out the # elements this provides, and bitcast it or slice it up
// as required.
//}
if (!V->hasOneUse()) return false;
Instruction *I = dyn_cast<Instruction>(V);
if (I == 0) return false;
switch (I->getOpcode()) {
default: return false; // Unhandled case.
case Instruction::BitCast:
return CollectInsertionElements(I->getOperand(0), ElementIndex,
Elements, VecEltTy);
case Instruction::ZExt:
if (!isMultipleOfTypeSize(
I->getOperand(0)->getType()->getPrimitiveSizeInBits(),
VecEltTy))
return false;
return CollectInsertionElements(I->getOperand(0), ElementIndex,
Elements, VecEltTy);
case Instruction::Or:
return CollectInsertionElements(I->getOperand(0), ElementIndex,
Elements, VecEltTy) &&
CollectInsertionElements(I->getOperand(1), ElementIndex,
Elements, VecEltTy);
case Instruction::Shl: {
// Must be shifting by a constant that is a multiple of the element size.
ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1));
if (CI == 0) return false;
if (!isMultipleOfTypeSize(CI->getZExtValue(), VecEltTy)) return false;
unsigned IndexShift = getTypeSizeIndex(CI->getZExtValue(), VecEltTy);
return CollectInsertionElements(I->getOperand(0), ElementIndex+IndexShift,
Elements, VecEltTy);
}
}
}
/// OptimizeIntegerToVectorInsertions - If the input is an 'or' instruction, we
/// may be doing shifts and ors to assemble the elements of the vector manually.
/// Try to rip the code out and replace it with insertelements. This is to
/// optimize code like this:
///
/// %tmp37 = bitcast float %inc to i32
/// %tmp38 = zext i32 %tmp37 to i64
/// %tmp31 = bitcast float %inc5 to i32
/// %tmp32 = zext i32 %tmp31 to i64
/// %tmp33 = shl i64 %tmp32, 32
/// %ins35 = or i64 %tmp33, %tmp38
/// %tmp43 = bitcast i64 %ins35 to <2 x float>
///
/// Into two insertelements that do "buildvector{%inc, %inc5}".
static Value *OptimizeIntegerToVectorInsertions(BitCastInst &CI,
InstCombiner &IC) {
const VectorType *DestVecTy = cast<VectorType>(CI.getType());
Value *IntInput = CI.getOperand(0);
SmallVector<Value*, 8> Elements(DestVecTy->getNumElements());
if (!CollectInsertionElements(IntInput, 0, Elements,
DestVecTy->getElementType()))
return 0;
// If we succeeded, we know that all of the element are specified by Elements
// or are zero if Elements has a null entry. Recast this as a set of
// insertions.
Value *Result = Constant::getNullValue(CI.getType());
for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
if (Elements[i] == 0) continue; // Unset element.
Result = IC.Builder->CreateInsertElement(Result, Elements[i],
IC.Builder->getInt32(i));
}
return Result;
}
/// 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){
@ -1478,16 +1588,24 @@ Instruction *InstCombiner::visitBitCast(BitCastInst &CI) {
// FIXME: Canonicalize bitcast(insertelement) -> insertelement(bitcast)
}
// If this is a cast from an integer to vector, check to see if the input
// is a trunc or zext of a bitcast from vector. If so, we can replace all
// the casts with a shuffle and (potentially) a bitcast.
if (isa<IntegerType>(SrcTy) && (isa<TruncInst>(Src) || isa<ZExtInst>(Src))){
CastInst *SrcCast = cast<CastInst>(Src);
if (BitCastInst *BCIn = dyn_cast<BitCastInst>(SrcCast->getOperand(0)))
if (isa<VectorType>(BCIn->getOperand(0)->getType()))
if (Instruction *I = OptimizeVectorResize(BCIn->getOperand(0),
if (isa<IntegerType>(SrcTy)) {
// If this is a cast from an integer to vector, check to see if the input
// is a trunc or zext of a bitcast from vector. If so, we can replace all
// the casts with a shuffle and (potentially) a bitcast.
if (isa<TruncInst>(Src) || isa<ZExtInst>(Src)) {
CastInst *SrcCast = cast<CastInst>(Src);
if (BitCastInst *BCIn = dyn_cast<BitCastInst>(SrcCast->getOperand(0)))
if (isa<VectorType>(BCIn->getOperand(0)->getType()))
if (Instruction *I = OptimizeVectorResize(BCIn->getOperand(0),
cast<VectorType>(DestTy), *this))
return I;
return I;
}
// If the input is an 'or' instruction, we may be doing shifts and ors to
// assemble the elements of the vector manually. Try to rip the code out
// and replace it with insertelements.
if (Value *V = OptimizeIntegerToVectorInsertions(CI, *this))
return ReplaceInstUsesWith(CI, V);
}
}

4
lib/Transforms/InstCombine/InstCombineShifts.cpp
View File

@ -312,8 +312,8 @@ Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
// cast of lshr(shl(x,c1),c2) as well as other more complex cases.
if (I.getOpcode() != Instruction::AShr &&
CanEvaluateShifted(Op0, Op1->getZExtValue(), isLeftShift, *this)) {
DEBUG(dbgs() << "ICE: GetShiftedValue propagatin shift through expression"
" to eliminate shift:\n IN: " << *Op0 << "\nSH: " << I << "\n");
DEBUG(dbgs() << "ICE: GetShiftedValue propagating shift through expression"
" to eliminate shift:\n IN: " << *Op0 << "\n SH: " << I <<"\n");
return ReplaceInstUsesWith(I,
GetShiftedValue(Op0, Op1->getZExtValue(), isLeftShift, *this));

31
test/Transforms/InstCombine/bitcast.ll
View File

@ -60,3 +60,34 @@ define float @test3(<2 x float> %A, <2 x i64> %B) {
; CHECK-NEXT: %add = fadd float %tmp24, %tmp4
; CHECK-NEXT: ret float %add
}
define <2 x i32> @test4(i32 %A, i32 %B){
%tmp38 = zext i32 %A to i64
%tmp32 = zext i32 %B to i64
%tmp33 = shl i64 %tmp32, 32
%ins35 = or i64 %tmp33, %tmp38
%tmp43 = bitcast i64 %ins35 to <2 x i32>
ret <2 x i32> %tmp43
; CHECK: @test4
; CHECK-NEXT: insertelement <2 x i32> undef, i32 %A, i32 0
; CHECK-NEXT: insertelement <2 x i32> {{.*}}, i32 %B, i32 1
; CHECK-NEXT: ret <2 x i32>
}
; rdar://8360454
define <2 x float> @test5(float %A, float %B) {
%tmp37 = bitcast float %A to i32
%tmp38 = zext i32 %tmp37 to i64
%tmp31 = bitcast float %B to i32
%tmp32 = zext i32 %tmp31 to i64
%tmp33 = shl i64 %tmp32, 32
%ins35 = or i64 %tmp33, %tmp38
%tmp43 = bitcast i64 %ins35 to <2 x float>
ret <2 x float> %tmp43
; CHECK: @test5
; CHECK-NEXT: insertelement <2 x float> undef, float %A, i32 0
; CHECK-NEXT: insertelement <2 x float> {{.*}}, float %B, i32 1
; CHECK-NEXT: ret <2 x float>
}