forked from OSchip/llvm-project
Turn srem -> urem when neither input has their sign bit set. This triggers
8 times in vortex, allowing the srems to be turned into shrs: OLD: %tmp.104 = rem int %tmp.5.i37, 16 ; <int> [#uses=1] NEW: %tmp.104 = rem uint %tmp.5.i37, 16 ; <uint> [#uses=0] OLD: %tmp.98 = rem int %tmp.5.i24, 16 ; <int> [#uses=1] NEW: %tmp.98 = rem uint %tmp.5.i24, 16 ; <uint> [#uses=0] OLD: %tmp.91 = rem int %tmp.5.i19, 8 ; <int> [#uses=1] NEW: %tmp.91 = rem uint %tmp.5.i19, 8 ; <uint> [#uses=0] OLD: %tmp.88 = rem int %tmp.5.i14, 8 ; <int> [#uses=1] NEW: %tmp.88 = rem uint %tmp.5.i14, 8 ; <uint> [#uses=0] OLD: %tmp.85 = rem int %tmp.5.i9, 1024 ; <int> [#uses=2] NEW: %tmp.85 = rem uint %tmp.5.i9, 1024 ; <uint> [#uses=0] OLD: %tmp.82 = rem int %tmp.5.i, 512 ; <int> [#uses=2] NEW: %tmp.82 = rem uint %tmp.5.i1, 512 ; <uint> [#uses=0] OLD: %tmp.48.i = rem int %tmp.5.i.i161, 4 ; <int> [#uses=1] NEW: %tmp.48.i = rem uint %tmp.5.i.i161, 4 ; <uint> [#uses=0] OLD: %tmp.20.i2 = rem int %tmp.5.i.i, 4 ; <int> [#uses=1] NEW: %tmp.20.i2 = rem uint %tmp.5.i.i, 4 ; <uint> [#uses=0] it also occurs 9 times in gcc, but with odd constant divisors (1009 and 61) so the payoff isn't as great. llvm-svn: 24189
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@ -1246,7 +1246,7 @@ Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
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Instruction *InstCombiner::visitRem(BinaryOperator &I) {
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Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
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if (I.getType()->isSigned())
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if (I.getType()->isSigned()) {
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if (Value *RHSNeg = dyn_castNegVal(Op1))
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if (!isa<ConstantSInt>(RHSNeg) ||
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cast<ConstantSInt>(RHSNeg)->getValue() > 0) {
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@ -1255,6 +1255,24 @@ Instruction *InstCombiner::visitRem(BinaryOperator &I) {
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I.setOperand(1, RHSNeg);
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return &I;
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}
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// If the top bits of both operands are zero (i.e. we can prove they are
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// unsigned inputs), turn this into a urem.
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ConstantIntegral *MaskV = ConstantSInt::getMinValue(I.getType());
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if (MaskedValueIsZero(Op1, MaskV) && MaskedValueIsZero(Op0, MaskV)) {
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const Type *NTy = Op0->getType()->getUnsignedVersion();
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Instruction *LHS = new CastInst(Op0, NTy, Op0->getName());
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InsertNewInstBefore(LHS, I);
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Value *RHS;
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if (Constant *R = dyn_cast<Constant>(Op1))
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RHS = ConstantExpr::getCast(R, NTy);
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else
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RHS = InsertNewInstBefore(new CastInst(Op1, NTy, Op1->getName()), I);
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Instruction *Rem = BinaryOperator::createRem(LHS, RHS, I.getName());
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InsertNewInstBefore(Rem, I);
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return new CastInst(Rem, I.getType());
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}
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}
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if (isa<UndefValue>(Op0)) // undef % X -> 0
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return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
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