From afe4539f8ea9e12404dce0d67b421d8decb2f0fb Mon Sep 17 00:00:00 2001 From: Duncan Sands Date: Fri, 16 Nov 2012 18:55:49 +0000 Subject: [PATCH] Fix PR14361: wrong simplification of A+B==B+A. You may think that the old logic replaced by this patch is equivalent to the new logic, but you'd be wrong, and that's exactly where the bug was. There's a similar bug in instsimplify which manifests itself as instsimplify failing to simplify this, rather than doing it wrong, see next commit. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168181 91177308-0d34-0410-b5e6-96231b3b80d8 --- .../InstCombine/InstCombineCompares.cpp | 16 ++++++++++++++-- test/Transforms/InstCombine/icmp.ll | 18 ++++++++++++++++++ 2 files changed, 32 insertions(+), 2 deletions(-) diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp index 8cb4a59cba9..e223a049f0b 100644 --- a/lib/Transforms/InstCombine/InstCombineCompares.cpp +++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp @@ -2356,8 +2356,20 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) { // Try not to increase register pressure. BO0->hasOneUse() && BO1->hasOneUse()) { // Determine Y and Z in the form icmp (X+Y), (X+Z). - Value *Y = (A == C || A == D) ? B : A; - Value *Z = (C == A || C == B) ? D : C; + Value *Y, *Z; + if (A == C) { + Y = B; + Z = D; + } else if (A == D) { + Y = B; + Z = C; + } else if (B == C) { + Y = A; + Z = D; + } else if (B == D) { + Y = A; + Z = C; + } return new ICmpInst(Pred, Y, Z); } diff --git a/test/Transforms/InstCombine/icmp.ll b/test/Transforms/InstCombine/icmp.ll index eaff87d695e..8e064a4f2fc 100644 --- a/test/Transforms/InstCombine/icmp.ll +++ b/test/Transforms/InstCombine/icmp.ll @@ -659,3 +659,21 @@ define i1 @test64(i8 %a, i32 %b) nounwind { ; CHECK-NEXT: %c = icmp eq i8 %1, %a ; CHECK-NEXT: ret i1 %c } + +define i1 @test65(i64 %A, i64 %B) { + %s1 = add i64 %A, %B + %s2 = add i64 %A, %B + %cmp = icmp eq i64 %s1, %s2 +; CHECK: @test65 +; CHECK-NEXT: ret i1 true + ret i1 %cmp +} + +define i1 @test66(i64 %A, i64 %B) { + %s1 = add i64 %A, %B + %s2 = add i64 %B, %A + %cmp = icmp eq i64 %s1, %s2 +; CHECK: @test66 +; CHECK-NEXT: ret i1 true + ret i1 %cmp +} -- 2.34.1