diff options
| -rw-r--r-- | lib/Analysis/InstructionSimplify.cpp | 18 | ||||
| -rw-r--r-- | test/Transforms/InstSimplify/compare.ll | 16 |
2 files changed, 34 insertions, 0 deletions
diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp index 982dacb50b..c23abb7808 100644 --- a/lib/Analysis/InstructionSimplify.cpp +++ b/lib/Analysis/InstructionSimplify.cpp @@ -1434,6 +1434,9 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, return ConstantInt::getTrue(CI->getContext()); break; } + + // TODO: integer div and rem with constant RHS all produce values in a + // constant range. We should check whether the comparison is a tautology. } // Compare of cast, for example (zext X) != 0 -> X != 0 @@ -1644,6 +1647,21 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, } } + if (LBO && match(LBO, m_URem(m_Value(), m_Specific(RHS)))) { + switch (Pred) { + default: + break; + case ICmpInst::ICMP_EQ: + case ICmpInst::ICMP_UGT: + case ICmpInst::ICMP_UGE: + return ConstantInt::getFalse(RHS->getContext()); + case ICmpInst::ICMP_NE: + case ICmpInst::ICMP_ULT: + case ICmpInst::ICMP_ULE: + return ConstantInt::getTrue(RHS->getContext()); + } + } + // If the comparison is with the result of a select instruction, check whether // comparing with either branch of the select always yields the same value. if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)) diff --git a/test/Transforms/InstSimplify/compare.ll b/test/Transforms/InstSimplify/compare.ll index 250e44ce34..f392d3a5e7 100644 --- a/test/Transforms/InstSimplify/compare.ll +++ b/test/Transforms/InstSimplify/compare.ll @@ -187,3 +187,19 @@ define i1 @select4(i1 %cond) { ret i1 %c ; CHECK: ret i1 %cond } + +define i1 @urem1(i32 %X, i32 %Y) { +; CHECK: @urem1 + %A = urem i32 %X, %Y + %B = icmp ult i32 %A, %Y + ret i1 %B +; CHECK: ret i1 true +} + +define i1 @urem2(i32 %X, i32 %Y) { +; CHECK: @urem2 + %A = urem i32 %X, %Y + %B = icmp eq i32 %A, %Y + ret i1 %B +; CHECK ret i1 false +} |