aboutsummaryrefslogtreecommitdiffstats
path: root/lib/Transforms/InstCombine/InstCombineCompares.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'lib/Transforms/InstCombine/InstCombineCompares.cpp')
-rw-r--r--lib/Transforms/InstCombine/InstCombineCompares.cpp31
1 files changed, 21 insertions, 10 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp
index bca1304534b6..428f94bb5e93 100644
--- a/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -4039,11 +4039,6 @@ Instruction *InstCombiner::foldICmpUsingKnownBits(ICmpInst &I) {
Constant *CMinus1 = ConstantInt::get(Op0->getType(), *CmpC - 1);
return new ICmpInst(ICmpInst::ICMP_EQ, Op0, CMinus1);
}
- // (x <u 2147483648) -> (x >s -1) -> true if sign bit clear
- if (CmpC->isMinSignedValue()) {
- Constant *AllOnes = Constant::getAllOnesValue(Op0->getType());
- return new ICmpInst(ICmpInst::ICMP_SGT, Op0, AllOnes);
- }
}
break;
}
@@ -4063,11 +4058,6 @@ Instruction *InstCombiner::foldICmpUsingKnownBits(ICmpInst &I) {
if (*CmpC == Op0Max - 1)
return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
ConstantInt::get(Op1->getType(), *CmpC + 1));
-
- // (x >u 2147483647) -> (x <s 0) -> true if sign bit set
- if (CmpC->isMaxSignedValue())
- return new ICmpInst(ICmpInst::ICMP_SLT, Op0,
- Constant::getNullValue(Op0->getType()));
}
break;
}
@@ -4299,6 +4289,27 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
(SI->getOperand(2) == Op0 && SI->getOperand(1) == Op1))
return nullptr;
+ // FIXME: We only do this after checking for min/max to prevent infinite
+ // looping caused by a reverse canonicalization of these patterns for min/max.
+ // FIXME: The organization of folds is a mess. These would naturally go into
+ // canonicalizeCmpWithConstant(), but we can't move all of the above folds
+ // down here after the min/max restriction.
+ ICmpInst::Predicate Pred = I.getPredicate();
+ const APInt *C;
+ if (match(Op1, m_APInt(C))) {
+ // For i32: x >u 2147483647 -> x <s 0 -> true if sign bit set
+ if (Pred == ICmpInst::ICMP_UGT && C->isMaxSignedValue()) {
+ Constant *Zero = Constant::getNullValue(Op0->getType());
+ return new ICmpInst(ICmpInst::ICMP_SLT, Op0, Zero);
+ }
+
+ // For i32: x <u 2147483648 -> x >s -1 -> true if sign bit clear
+ if (Pred == ICmpInst::ICMP_ULT && C->isMinSignedValue()) {
+ Constant *AllOnes = Constant::getAllOnesValue(Op0->getType());
+ return new ICmpInst(ICmpInst::ICMP_SGT, Op0, AllOnes);
+ }
+ }
+
if (Instruction *Res = foldICmpInstWithConstant(I))
return Res;