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Reapply r108378, with bugfixes, testcase, and improved comment formatting. 

This now passes LIT, nighty test, and llvm-gcc bootstrap on my machine.

llvm-svn: 108422
This commit is contained in:
Owen Anderson 2010-07-15 15:00:23 +00:00
parent 26ec65ac3c
commit 7151dfd48a
3 changed files with 62 additions and 0 deletions
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19
llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
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@ -472,6 +472,25 @@ Value *InstCombiner::FoldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS) {
Value *NewOr = Builder->CreateOr(Val, Val2);
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 && !CI1->isZero() && CI2 && !CI2->isZero() &&
CI1->getValue().operator&(CI2->getValue()) == 0) {
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:

28
llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
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@ -699,6 +699,34 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
SI.setOperand(2, TrueVal);
return &SI;
}
// select (A == 0 | B == 0), T, F--> select (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->hasOneUse() &&
CondInst->getOpcode() == Instruction::Or) {
ICmpInst *LHSCmp = dyn_cast<ICmpInst>(CondInst->getOperand(0));
ICmpInst *RHSCmp = dyn_cast<ICmpInst>(CondInst->getOperand(1));
if (LHSCmp && LHSCmp->hasOneUse() &&
LHSCmp->getPredicate() == ICmpInst::ICMP_EQ &&
RHSCmp && RHSCmp->hasOneUse() &&
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;
}

15
llvm/test/Transforms/InstCombine/bit-checks.ll Normal file
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@ -0,0 +1,15 @@
; This test makes sure that these instructions are properly eliminated.
;
; RUN: opt < %s -instcombine -S | \
; RUN: not grep {tobool}
; END.
define i32 @main(i32 %argc, i8** %argv) nounwind ssp {
entry:
%and = and i32 %argc, 1 ; <i32> [#uses=1]
%tobool = icmp ne i32 %and, 0 ; <i1> [#uses=1]
%and2 = and i32 %argc, 2 ; <i32> [#uses=1]
%tobool3 = icmp ne i32 %and2, 0 ; <i1> [#uses=1]
%or.cond = and i1 %tobool, %tobool3 ; <i1> [#uses=1]
%retval.0 = select i1 %or.cond, i32 2, i32 1 ; <i32> [#uses=1]
ret i32 %retval.0
}