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Fix logic error optimizing "icmp pred (urem X, Y), Y" where pred is signed.

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Fixes PR16605.

llvm-svn: 186229
This commit is contained in:
Nick Lewycky 2013-07-12 23:42:57 +00:00
parent 6f48f304ac
commit 35aeb68b53
2 changed files with 16 additions and 5 deletions
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11
lib/Analysis/InstructionSimplify.cpp
View File

@ -2246,6 +2246,7 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
}
}
// icmp pred (urem X, Y), Y
if (LBO && match(LBO, m_URem(m_Value(), m_Specific(RHS)))) {
bool KnownNonNegative, KnownNegative;
switch (Pred) {
@ -2253,7 +2254,7 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
break;
case ICmpInst::ICMP_SGT:
case ICmpInst::ICMP_SGE:
ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.TD);
ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.TD);
if (!KnownNonNegative)
break;
// fall-through
@ -2263,7 +2264,7 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
return getFalse(ITy);
case ICmpInst::ICMP_SLT:
case ICmpInst::ICMP_SLE:
ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.TD);
ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.TD);
if (!KnownNonNegative)
break;
// fall-through
@ -2273,6 +2274,8 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
return getTrue(ITy);
}
}
// icmp pred X, (urem Y, X)
if (RBO && match(RBO, m_URem(m_Value(), m_Specific(LHS)))) {
bool KnownNonNegative, KnownNegative;
switch (Pred) {
@ -2280,7 +2283,7 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
break;
case ICmpInst::ICMP_SGT:
case ICmpInst::ICMP_SGE:
ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.TD);
ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.TD);
if (!KnownNonNegative)
break;
// fall-through
@ -2290,7 +2293,7 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
return getTrue(ITy);
case ICmpInst::ICMP_SLT:
case ICmpInst::ICMP_SLE:
ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.TD);
ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.TD);
if (!KnownNonNegative)
break;
// fall-through

10
test/Transforms/InstSimplify/compare.ll
View File

@ -480,7 +480,7 @@ define i1 @urem5(i16 %X, i32 %Y) {
%B = urem i32 %A, %Y
%C = icmp slt i32 %B, %Y
ret i1 %C
; CHECK: ret i1 true
; CHECK-NOT: ret i1 true
}
define i1 @urem6(i32 %X, i32 %Y) {
@ -491,6 +491,14 @@ define i1 @urem6(i32 %X, i32 %Y) {
; CHECK: ret i1 true
}
define i1 @urem7(i32 %X) {
; CHECK: @urem7
%A = urem i32 1, %X
%B = icmp sgt i32 %A, %X
ret i1 %B
; CHECK-NOT: ret i1 false
}
define i1 @srem1(i32 %X) {
; CHECK: @srem1
%A = srem i32 %X, -5