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Add instcombine transforms to optimize tests of multiple bits of the same value into a single larger comparison.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@108378 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson
2010-07-14 23:33:51 +00:00
parent 14904ce25c
commit bd129a7460
2 changed files with 43 additions and 0 deletions
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18
lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
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@@ -472,6 +472,24 @@ Value *InstCombiner::FoldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS) {
Value *NewOr = Builder->CreateOr(Val, Val2); Value *NewOr = Builder->CreateOr(Val, Val2);
return Builder->CreateICmp(LHSCC, NewOr, LHSCst); return Builder->CreateICmp(LHSCC, NewOr, LHSCst);
} }
// (icmp ne (A & C1) 0) & (icmp ne (A & C2), 0) -->
// (icmp eq (A & (C1|C2)), (C1|C2))
if (LHSCC == ICmpInst::ICMP_NE && LHSCst->isZero()) {
Instruction *I1 = dyn_cast<Instruction>(Val);
Instruction *I2 = dyn_cast<Instruction>(Val2);
if (I1 && I1->getOpcode() == Instruction::And &&
I2 && I2->getOpcode() == Instruction::And &&
I1->getOperand(0) == I1->getOperand(0)) {
ConstantInt *CI1 = dyn_cast<ConstantInt>(I1->getOperand(1));
ConstantInt *CI2 = dyn_cast<ConstantInt>(I2->getOperand(1));
if (CI1 && CI2) {
Constant *ConstOr = ConstantExpr::getOr(CI1, CI2);
Value *NewAnd = Builder->CreateAnd(I1->getOperand(0), ConstOr);
return Builder->CreateICmp(ICmpInst::ICMP_EQ, NewAnd, ConstOr);
}
}
}
} }
// From here on, we only handle: // From here on, we only handle:

25
lib/Transforms/InstCombine/InstCombineSelect.cpp
View File

@@ -699,6 +699,31 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
SI.setOperand(2, TrueVal); SI.setOperand(2, TrueVal);
return &SI; return &SI;
} }
// select (or (A == 0) (B == 0)) T, F--> select (and (A != 0) (B != 0)) F, T
// Note: This is a canonicalization rather than an optimization, and is used
// to expose opportunities to other instcombine transforms.
Instruction* CondInst = dyn_cast<Instruction>(CondVal);
if (CondInst && CondInst->getOpcode() == Instruction::Or) {
ICmpInst *LHSCmp = dyn_cast<ICmpInst>(CondInst->getOperand(0));
ICmpInst *RHSCmp = dyn_cast<ICmpInst>(CondInst->getOperand(1));
if (LHSCmp && LHSCmp->getPredicate() == ICmpInst::ICMP_EQ &&
RHSCmp && RHSCmp->getPredicate() == ICmpInst::ICMP_EQ) {
ConstantInt* C1 = dyn_cast<ConstantInt>(LHSCmp->getOperand(1));
ConstantInt* C2 = dyn_cast<ConstantInt>(RHSCmp->getOperand(1));
if (C1 && C1->isZero() && C2 && C2->isZero()) {
LHSCmp->setPredicate(ICmpInst::ICMP_NE);
RHSCmp->setPredicate(ICmpInst::ICMP_NE);
Value *And =
InsertNewInstBefore(BinaryOperator::CreateAnd(LHSCmp, RHSCmp,
"and."+CondVal->getName()), SI);
SI.setOperand(0, And);
SI.setOperand(1, FalseVal);
SI.setOperand(2, TrueVal);
return &SI;
}
}
}
return 0; return 0;
} }