diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp index 13a5cd96f7b..d98f966f8ca 100644 --- a/lib/Transforms/InstCombine/InstCombineCompares.cpp +++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp @@ -2318,32 +2318,6 @@ static bool swapMayExposeCSEOpportunities(const Value * Op0, return GlobalSwapBenefits > 0; } -// Helper function to check whether Op represents a lshr/ashr exact -// instruction. For example: -// (icmp (ashr exact const2, A), const1) -> icmp A, Log2(const2/const1) -// Here if Op represents -> (ashr exact const2, A), and CI represents -// const1, we compute Quotient as const2/const1. - -static bool checkShrExact(Value *Op, APInt &Quotient, const ConstantInt *CI, - Value *&A) { - - ConstantInt *CI2; - if (match(Op, m_AShr(m_ConstantInt(CI2), m_Value(A))) && - (cast(Op)->isExact())) { - Quotient = CI2->getValue().sdiv(CI->getValue()); - return true; - } - - // Handle the case for lhsr. - if (match(Op, m_LShr(m_ConstantInt(CI2), m_Value(A))) && - (cast(Op)->isExact())) { - Quotient = CI2->getValue().udiv(CI->getValue()); - return true; - } - - return false; -} - Instruction *InstCombiner::visitICmpInst(ICmpInst &I) { bool Changed = false; Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); @@ -2465,20 +2439,6 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) { return new ICmpInst(I.getPredicate(), A, B); } - // PR19753: - // (icmp (ashr exact const2, A), const1) -> icmp A, Log2(const2/const1) - // Cases where const1 doesn't divide const2 exactly or Quotient is not - // exact of log2 are handled by SimplifyICmpInst call above where we - // return false. Similar for lshr. - { - APInt Quotient; - if (checkShrExact(Op0, Quotient, CI, A)) { - unsigned shift = Quotient.logBase2(); - return new ICmpInst(I.getPredicate(), A, - ConstantInt::get(A->getType(), shift)); - } - } - // If we have an icmp le or icmp ge instruction, turn it into the // appropriate icmp lt or icmp gt instruction. This allows us to rely on // them being folded in the code below. The SimplifyICmpInst code has diff --git a/test/Transforms/InstCombine/icmp.ll b/test/Transforms/InstCombine/icmp.ll index 8e107edd762..560fbcbfae9 100644 --- a/test/Transforms/InstCombine/icmp.ll +++ b/test/Transforms/InstCombine/icmp.ll @@ -1382,19 +1382,3 @@ define i1 @icmp_neg_cst_slt(i32 %a) { %2 = icmp slt i32 %1, -10 ret i1 %2 } - -; CHECK-LABEL: @exact_ashr_eq_false -; CHECK-NEXT: icmp eq i32 %a, 1 -define i1 @exact_ashr_eq_false(i32 %a) { - %shr = ashr exact i32 -30, %a - %cmp = icmp eq i32 %shr, -15 - ret i1 %cmp -} - -; CHECK-LABEL: @exact_lhsr -; CHECK-NEXT: icmp eq i32 %a, 3 -define i1 @exact_lhsr(i32 %a) { - %shr = lshr exact i32 80, %a - %cmp = icmp eq i32 %shr, 10 - ret i1 %cmp -}