diff options
| -rw-r--r-- | lib/Analysis/InstructionSimplify.cpp | 74 | ||||
| -rw-r--r-- | test/Transforms/InstSimplify/compare.ll | 9 |
2 files changed, 54 insertions, 29 deletions
diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp index 6bef0aedee..83881deccf 100644 --- a/lib/Analysis/InstructionSimplify.cpp +++ b/lib/Analysis/InstructionSimplify.cpp @@ -416,39 +416,55 @@ static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS, } assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!"); SelectInst *SI = cast<SelectInst>(LHS); + Value *Cond = SI->getCondition(); + Value *TV = SI->getTrueValue(); + Value *FV = SI->getFalseValue(); // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it. // Does "cmp TV, RHS" simplify? - if (Value *TCmp = SimplifyCmpInst(Pred, SI->getTrueValue(), RHS, TD, DT, - MaxRecurse)) { - // It does! Does "cmp FV, RHS" simplify? - if (Value *FCmp = SimplifyCmpInst(Pred, SI->getFalseValue(), RHS, TD, DT, - MaxRecurse)) { - // It does! If they simplified to the same value, then use it as the - // result of the original comparison. - if (TCmp == FCmp) - return TCmp; - Value *Cond = SI->getCondition(); - // If the false value simplified to false, then the result of the compare - // is equal to "Cond && TCmp". This also catches the case when the false - // value simplified to false and the true value to true, returning "Cond". - if (match(FCmp, m_Zero())) - if (Value *V = SimplifyAndInst(Cond, TCmp, TD, DT, MaxRecurse)) - return V; - // If the true value simplified to true, then the result of the compare - // is equal to "Cond || FCmp". - if (match(TCmp, m_One())) - if (Value *V = SimplifyOrInst(Cond, FCmp, TD, DT, MaxRecurse)) - return V; - // Finally, if the false value simplified to true and the true value to - // false, then the result of the compare is equal to "!Cond". - if (match(FCmp, m_One()) && match(TCmp, m_Zero())) - if (Value *V = - SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()), - TD, DT, MaxRecurse)) - return V; - } + Value *TCmp = SimplifyCmpInst(Pred, TV, RHS, TD, DT, MaxRecurse); + if (!TCmp) { + // It didn't simplify. However if "cmp TV, RHS" is equal to the select + // condition itself then we can replace it with 'true'. + if (match(Cond, m_ICmp(Pred, m_Specific(TV), m_Specific(RHS)))) + TCmp = getTrue(Cond->getType()); + } + if (!TCmp) + return 0; + + // Does "cmp FV, RHS" simplify? + Value *FCmp = SimplifyCmpInst(Pred, FV, RHS, TD, DT, MaxRecurse); + if (!FCmp) { + // It didn't simplify. However if "cmp FV, RHS" is equal to the select + // condition itself then we can replace it with 'false'. + if (match(Cond, m_ICmp(Pred, m_Specific(FV), m_Specific(RHS)))) + FCmp = getFalse(Cond->getType()); } + if (!FCmp) + return 0; + + // If both sides simplified to the same value, then use it as the result of + // the original comparison. + if (TCmp == FCmp) + return TCmp; + // If the false value simplified to false, then the result of the compare + // is equal to "Cond && TCmp". This also catches the case when the false + // value simplified to false and the true value to true, returning "Cond". + if (match(FCmp, m_Zero())) + if (Value *V = SimplifyAndInst(Cond, TCmp, TD, DT, MaxRecurse)) + return V; + // If the true value simplified to true, then the result of the compare + // is equal to "Cond || FCmp". + if (match(TCmp, m_One())) + if (Value *V = SimplifyOrInst(Cond, FCmp, TD, DT, MaxRecurse)) + return V; + // Finally, if the false value simplified to true and the true value to + // false, then the result of the compare is equal to "!Cond". + if (match(FCmp, m_One()) && match(TCmp, m_Zero())) + if (Value *V = + SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()), + TD, DT, MaxRecurse)) + return V; return 0; } diff --git a/test/Transforms/InstSimplify/compare.ll b/test/Transforms/InstSimplify/compare.ll index 57727c9ab7..df33122574 100644 --- a/test/Transforms/InstSimplify/compare.ll +++ b/test/Transforms/InstSimplify/compare.ll @@ -204,6 +204,15 @@ define i1 @select4(i1 %cond) { ; CHECK: ret i1 %cond } +define i1 @select5(i32 %x) { +; CHECK: @select5 + %c = icmp eq i32 %x, 0 + %s = select i1 %c, i32 1, i32 %x + %c2 = icmp eq i32 %s, 0 + ret i1 %c2 +; CHECK: ret i1 false +} + define i1 @urem1(i32 %X, i32 %Y) { ; CHECK: @urem1 %A = urem i32 %X, %Y |