From 9bdb91889020b3e61cba26adb1b9c64a24c09f95 Mon Sep 17 00:00:00 2001 From: Max Kazantsev Date: Thu, 4 Jun 2020 18:54:23 +0700 Subject: [PATCH] [InstCombine][NFC] Factor out constant check We plan to add more transforms here. Besides, this check should be done in the beginning just from function's name. --- .../Transforms/InstCombine/InstCombineCompares.cpp | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp index 48375a1a323f..e7371d28c745 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp @@ -1432,6 +1432,13 @@ Instruction *InstCombiner::foldICmpWithZero(ICmpInst &Cmp) { /// possible that code has been made unnecessary - do we canonicalize IR to /// overflow/saturating intrinsics or not?). Instruction *InstCombiner::foldICmpWithConstant(ICmpInst &Cmp) { + Value *Op0 = Cmp.getOperand(0), *Op1 = Cmp.getOperand(1); + ConstantInt *CI; + + // Make sure that the RHS operand is a constant. + if (!match(Op1, m_ConstantInt(CI))) + return nullptr; + // Match the following pattern, which is a common idiom when writing // overflow-safe integer arithmetic functions. The source performs an addition // in wider type and explicitly checks for overflow using comparisons against @@ -1444,10 +1451,9 @@ Instruction *InstCombiner::foldICmpWithConstant(ICmpInst &Cmp) { // sum = a + b // if (sum+128 >u 255) ... -> llvm.sadd.with.overflow.i8 CmpInst::Predicate Pred = Cmp.getPredicate(); - Value *Op0 = Cmp.getOperand(0), *Op1 = Cmp.getOperand(1); Value *A, *B; - ConstantInt *CI, *CI2; // I = icmp ugt (add (add A, B), CI2), CI - if (Pred == ICmpInst::ICMP_UGT && match(Op1, m_ConstantInt(CI)) && + ConstantInt *CI2; // I = icmp ugt (add (add A, B), CI2), CI + if (Pred == ICmpInst::ICMP_UGT && match(Op0, m_Add(m_Add(m_Value(A), m_Value(B)), m_ConstantInt(CI2)))) if (Instruction *Res = processUGT_ADDCST_ADD(Cmp, A, B, CI2, CI, *this)) return Res;