diff options
| -rw-r--r-- | lib/Transforms/InstCombine/InstCombineAndOrXor.cpp | 12 | ||||
| -rw-r--r-- | test/Transforms/InstCombine/icmp.ll | 11 |
2 files changed, 23 insertions, 0 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp index ecae3b6045..0fd1e2b2e4 100644 --- a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp +++ b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp @@ -1524,6 +1524,18 @@ Value *InstCombiner::FoldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS) { AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst); return Builder->CreateICmpULT(Add, AddCST); } + + if (LHS->getOperand(0) == RHS->getOperand(0)) { + // if LHSCst and RHSCst differ with only one bit: + // (A == C1 || A == C2) -> (A & ~(C1 ^ C2)) == C1 + APInt Xor = LHSCst->getValue() ^ RHSCst->getValue(); + if (Xor.isPowerOf2()) { + Value *NegCst = Builder->getInt(~Xor); + Value *And = Builder->CreateAnd(LHS->getOperand(0), NegCst); + return Builder->CreateICmp(ICmpInst::ICMP_EQ, And, LHSCst); + } + } + break; // (X == 13 | X == 15) -> no change case ICmpInst::ICMP_UGT: // (X == 13 | X u> 14) -> no change case ICmpInst::ICMP_SGT: // (X == 13 | X s> 14) -> no change diff --git a/test/Transforms/InstCombine/icmp.ll b/test/Transforms/InstCombine/icmp.ll index 138b10eaa0..5102a9cb6a 100644 --- a/test/Transforms/InstCombine/icmp.ll +++ b/test/Transforms/InstCombine/icmp.ll @@ -694,3 +694,14 @@ define i1 @test68(i32 %x) nounwind uwtable { %cmp = icmp sgt i32 %and, 30 ret i1 %cmp } + +; PR14708 +; CHECK: @test69 +; CHECK: %1 = and i32 %c, -33 +; CHECK: %2 = icmp eq i32 %1, 65 +define i1 @test69(i32 %c) nounwind uwtable { + %1 = icmp eq i32 %c, 97 + %2 = icmp eq i32 %c, 65 + %3 = or i1 %1, %2 + ret i1 %3 +} |