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Perform factorization as a last resort of unsafe fadd/fsub simplification.
Rules include:
1)1 x*y +/- x*z => x*(y +/- z)
(the order of operands dosen't matter)
2) y/x +/- z/x => (y +/- z)/x
The transformation is disabled if the new add/sub expr "y +/- z" is a
denormal/naz/inifinity.
rdar://12911472
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177088 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Shuxin Yang
parent
d9e90b20e2
commit
a0c9939873
@ -150,7 +150,9 @@ namespace {
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typedef SmallVector<const FAddend*, 4> AddendVect;
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Value *simplifyFAdd(AddendVect& V, unsigned InstrQuota);
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Value *performFactorization(Instruction *I);
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/// Convert given addend to a Value
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Value *createAddendVal(const FAddend &A, bool& NeedNeg);
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@ -159,6 +161,7 @@ namespace {
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Value *createFSub(Value *Opnd0, Value *Opnd1);
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Value *createFAdd(Value *Opnd0, Value *Opnd1);
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Value *createFMul(Value *Opnd0, Value *Opnd1);
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Value *createFDiv(Value *Opnd0, Value *Opnd1);
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Value *createFNeg(Value *V);
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Value *createNaryFAdd(const AddendVect& Opnds, unsigned InstrQuota);
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void createInstPostProc(Instruction *NewInst);
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@ -388,6 +391,78 @@ unsigned FAddend::drillAddendDownOneStep
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return BreakNum;
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}
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// Try to perform following optimization on the input instruction I. Return the
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// simplified expression if was successful; otherwise, return 0.
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//
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// Instruction "I" is Simplified into
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// -------------------------------------------------------
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// (x * y) +/- (x * z) x * (y +/- z)
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// (y / x) +/- (z / x) (y +/- z) / x
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//
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Value *FAddCombine::performFactorization(Instruction *I) {
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assert((I->getOpcode() == Instruction::FAdd ||
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I->getOpcode() == Instruction::FSub) && "Expect add/sub");
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Instruction *I0 = dyn_cast<Instruction>(I->getOperand(0));
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Instruction *I1 = dyn_cast<Instruction>(I->getOperand(1));
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if (!I0 || !I1 || I0->getOpcode() != I1->getOpcode())
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return 0;
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bool isMpy = false;
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if (I0->getOpcode() == Instruction::FMul)
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isMpy = true;
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else if (I0->getOpcode() != Instruction::FDiv)
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return 0;
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Value *Opnd0_0 = I0->getOperand(0);
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Value *Opnd0_1 = I0->getOperand(1);
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Value *Opnd1_0 = I1->getOperand(0);
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Value *Opnd1_1 = I1->getOperand(1);
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// Input Instr I Factor AddSub0 AddSub1
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// ----------------------------------------------
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// (x*y) +/- (x*z) x y z
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// (y/x) +/- (z/x) x y z
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//
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Value *Factor = 0;
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Value *AddSub0 = 0, *AddSub1 = 0;
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if (isMpy) {
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if (Opnd0_0 == Opnd1_0 || Opnd0_0 == Opnd1_1)
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Factor = Opnd0_0;
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else if (Opnd0_1 == Opnd1_0 || Opnd0_1 == Opnd1_1)
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Factor = Opnd0_1;
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if (Factor) {
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AddSub0 = (Factor == Opnd0_0) ? Opnd0_1 : Opnd0_0;
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AddSub1 = (Factor == Opnd1_0) ? Opnd1_1 : Opnd1_0;
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}
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} else if (Opnd0_1 == Opnd1_1) {
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Factor = Opnd0_1;
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AddSub0 = Opnd0_0;
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AddSub1 = Opnd1_0;
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}
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if (!Factor)
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return 0;
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// Create expression "NewAddSub = AddSub0 +/- AddsSub1"
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Value *NewAddSub = (I->getOpcode() == Instruction::FAdd) ?
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createFAdd(AddSub0, AddSub1) :
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createFSub(AddSub0, AddSub1);
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if (ConstantFP *CFP = dyn_cast<ConstantFP>(NewAddSub)) {
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const APFloat &F = CFP->getValueAPF();
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if (!F.isNormal() || F.isDenormal())
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return 0;
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}
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if (isMpy)
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return createFMul(Factor, NewAddSub);
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return createFDiv(NewAddSub, Factor);
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}
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Value *FAddCombine::simplify(Instruction *I) {
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assert(I->hasUnsafeAlgebra() && "Should be in unsafe mode");
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@ -471,7 +546,8 @@ Value *FAddCombine::simplify(Instruction *I) {
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return R;
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}
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return 0;
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// step 6: Try factorization as the last resort,
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return performFactorization(I);
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}
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Value *FAddCombine::simplifyFAdd(AddendVect& Addends, unsigned InstrQuota) {
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@ -627,7 +703,8 @@ Value *FAddCombine::createNaryFAdd
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Value *FAddCombine::createFSub
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(Value *Opnd0, Value *Opnd1) {
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Value *V = Builder->CreateFSub(Opnd0, Opnd1);
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createInstPostProc(cast<Instruction>(V));
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if (Instruction *I = dyn_cast<Instruction>(V))
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createInstPostProc(I);
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return V;
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}
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@ -639,13 +716,22 @@ Value *FAddCombine::createFNeg(Value *V) {
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Value *FAddCombine::createFAdd
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(Value *Opnd0, Value *Opnd1) {
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Value *V = Builder->CreateFAdd(Opnd0, Opnd1);
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createInstPostProc(cast<Instruction>(V));
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if (Instruction *I = dyn_cast<Instruction>(V))
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createInstPostProc(I);
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return V;
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}
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Value *FAddCombine::createFMul(Value *Opnd0, Value *Opnd1) {
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Value *V = Builder->CreateFMul(Opnd0, Opnd1);
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createInstPostProc(cast<Instruction>(V));
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if (Instruction *I = dyn_cast<Instruction>(V))
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createInstPostProc(I);
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return V;
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}
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Value *FAddCombine::createFDiv(Value *Opnd0, Value *Opnd1) {
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Value *V = Builder->CreateFDiv(Opnd0, Opnd1);
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if (Instruction *I = dyn_cast<Instruction>(V))
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createInstPostProc(I);
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return V;
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}
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@ -350,3 +350,108 @@ define float @fdiv9(float %x) {
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; CHECK: @fdiv9
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; CHECK: fmul fast float %x, 5.000000e+00
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}
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; =========================================================================
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;
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; Testing-cases about factorization
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;
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; =========================================================================
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; x*z + y*z => (x+y) * z
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define float @fact_mul1(float %x, float %y, float %z) {
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%t1 = fmul fast float %x, %z
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%t2 = fmul fast float %y, %z
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%t3 = fadd fast float %t1, %t2
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ret float %t3
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; CHECK: @fact_mul1
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; CHECK: fmul fast float %1, %z
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}
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; z*x + y*z => (x+y) * z
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define float @fact_mul2(float %x, float %y, float %z) {
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%t1 = fmul fast float %z, %x
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%t2 = fmul fast float %y, %z
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%t3 = fsub fast float %t1, %t2
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ret float %t3
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; CHECK: @fact_mul2
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; CHECK: fmul fast float %1, %z
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}
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; z*x - z*y => (x-y) * z
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define float @fact_mul3(float %x, float %y, float %z) {
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%t2 = fmul fast float %z, %y
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%t1 = fmul fast float %z, %x
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%t3 = fsub fast float %t1, %t2
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ret float %t3
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; CHECK: @fact_mul3
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; CHECK: fmul fast float %1, %z
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}
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; x*z - z*y => (x-y) * z
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define float @fact_mul4(float %x, float %y, float %z) {
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%t1 = fmul fast float %x, %z
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%t2 = fmul fast float %z, %y
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%t3 = fsub fast float %t1, %t2
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ret float %t3
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; CHECK: @fact_mul4
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; CHECK: fmul fast float %1, %z
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}
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; x/y + x/z, no xform
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define float @fact_div1(float %x, float %y, float %z) {
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%t1 = fdiv fast float %x, %y
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%t2 = fdiv fast float %x, %z
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%t3 = fadd fast float %t1, %t2
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ret float %t3
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; CHECK: fact_div1
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; CHECK: fadd fast float %t1, %t2
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}
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; x/y + z/x; no xform
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define float @fact_div2(float %x, float %y, float %z) {
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%t1 = fdiv fast float %x, %y
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%t2 = fdiv fast float %z, %x
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%t3 = fadd fast float %t1, %t2
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ret float %t3
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; CHECK: fact_div2
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; CHECK: fadd fast float %t1, %t2
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}
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; y/x + z/x => (y+z)/x
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define float @fact_div3(float %x, float %y, float %z) {
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%t1 = fdiv fast float %y, %x
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%t2 = fdiv fast float %z, %x
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%t3 = fadd fast float %t1, %t2
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ret float %t3
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; CHECK: fact_div3
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; CHECK: fdiv fast float %1, %x
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}
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; y/x - z/x => (y-z)/x
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define float @fact_div4(float %x, float %y, float %z) {
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%t1 = fdiv fast float %y, %x
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%t2 = fdiv fast float %z, %x
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%t3 = fsub fast float %t1, %t2
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ret float %t3
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; CHECK: fact_div4
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; CHECK: fdiv fast float %1, %x
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}
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; y/x - z/x => (y-z)/x is disabled if y-z is denormal.
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define float @fact_div5(float %x) {
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%t1 = fdiv fast float 0x3810000000000000, %x
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%t2 = fdiv fast float 0x3800000000000000, %x
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%t3 = fadd fast float %t1, %t2
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ret float %t3
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; CHECK: fact_div5
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; CHECK: fdiv fast float 0x3818000000000000, %x
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}
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; y/x - z/x => (y-z)/x is disabled if y-z is denormal.
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define float @fact_div6(float %x) {
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%t1 = fdiv fast float 0x3810000000000000, %x
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%t2 = fdiv fast float 0x3800000000000000, %x
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%t3 = fsub fast float %t1, %t2
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ret float %t3
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; CHECK: fact_div6
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; CHECK: %t3 = fsub fast float %t1, %t2
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}
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