From 76ec6929ccfcb12455f08c4dd352792f42fbf969 Mon Sep 17 00:00:00 2001 From: QiYue Date: Wed, 4 Jun 2025 19:27:58 +0800 Subject: [PATCH 1/3] [InstCombine] Relax guard against FP min/max in select fold FCmp's equality and commutativity predicates do not work with min/max semantics Closes #142711 --- .../Transforms/InstCombine/InstructionCombining.cpp | 3 ++- llvm/test/Transforms/InstCombine/fcmp-select.ll | 11 +++++++++++ 2 files changed, 13 insertions(+), 1 deletion(-) diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp index 439a86d951a83..c85abd9b26d61 100644 --- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp +++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp @@ -1729,7 +1729,8 @@ Instruction *InstCombinerImpl::FoldOpIntoSelect(Instruction &Op, SelectInst *SI, if (auto *CI = dyn_cast(SI->getCondition())) { if (CI->hasOneUse()) { Value *Op0 = CI->getOperand(0), *Op1 = CI->getOperand(1); - if ((TV == Op0 && FV == Op1) || (FV == Op0 && TV == Op1)) + if (((TV == Op0 && FV == Op1) || (FV == Op0 && TV == Op1)) && + !CI->isEquality() && !CI->isCommutative()) return nullptr; } } diff --git a/llvm/test/Transforms/InstCombine/fcmp-select.ll b/llvm/test/Transforms/InstCombine/fcmp-select.ll index 408bc1cdc268f..bf08fbfc27302 100644 --- a/llvm/test/Transforms/InstCombine/fcmp-select.ll +++ b/llvm/test/Transforms/InstCombine/fcmp-select.ll @@ -268,3 +268,14 @@ define i1 @test_fcmp_select_var_const_unordered(double %x, double %y) { %cmp2 = fcmp ugt double %sel, 0x3E80000000000000 ret i1 %cmp2 } + +define i1 @test_fcmp_ord_select_fcmp_oeq_var_const(double %x) { +; CHECK-LABEL: @test_fcmp_ord_select_fcmp_oeq_var_const( +; CHECK-NEXT: [[CMP1:%.*]] = fcmp oeq double [[X:%.*]], 0.000000e+00 +; CHECK-NEXT: ret i1 [[CMP1]] +; + %cmp1 = fcmp ord double %x, 0.000000e+00 + %sel = select i1 %cmp1, double %x, double 0.000000e+00 + %cmp2 = fcmp oeq double %sel, 1.000000e+00 + ret i1 %cmp2 +} From a4fb76cdc1b7f45b2dc533b34cb7c34df081cfbf Mon Sep 17 00:00:00 2001 From: Acthink Yang Date: Fri, 6 Jun 2025 22:32:02 +0800 Subject: [PATCH 2/3] remove isEquality Co-authored-by: Yingwei Zheng --- llvm/lib/Transforms/InstCombine/InstructionCombining.cpp | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp index c85abd9b26d61..e261807bbc035 100644 --- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp +++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp @@ -1730,7 +1730,7 @@ Instruction *InstCombinerImpl::FoldOpIntoSelect(Instruction &Op, SelectInst *SI, if (CI->hasOneUse()) { Value *Op0 = CI->getOperand(0), *Op1 = CI->getOperand(1); if (((TV == Op0 && FV == Op1) || (FV == Op0 && TV == Op1)) && - !CI->isEquality() && !CI->isCommutative()) + !CI->isCommutative()) return nullptr; } } From 8f2cdcdb37afd9dbf9f093dc4ea24953e4c8bcae Mon Sep 17 00:00:00 2001 From: Acthink Yang Date: Sat, 7 Jun 2025 00:00:38 +0800 Subject: [PATCH 3/3] Update llvm/test/Transforms/InstCombine/fcmp-select.ll Co-authored-by: Yingwei Zheng --- llvm/test/Transforms/InstCombine/fcmp-select.ll | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/llvm/test/Transforms/InstCombine/fcmp-select.ll b/llvm/test/Transforms/InstCombine/fcmp-select.ll index bf08fbfc27302..053b233cb5f04 100644 --- a/llvm/test/Transforms/InstCombine/fcmp-select.ll +++ b/llvm/test/Transforms/InstCombine/fcmp-select.ll @@ -271,7 +271,7 @@ define i1 @test_fcmp_select_var_const_unordered(double %x, double %y) { define i1 @test_fcmp_ord_select_fcmp_oeq_var_const(double %x) { ; CHECK-LABEL: @test_fcmp_ord_select_fcmp_oeq_var_const( -; CHECK-NEXT: [[CMP1:%.*]] = fcmp oeq double [[X:%.*]], 0.000000e+00 +; CHECK-NEXT: [[CMP1:%.*]] = fcmp oeq double [[X:%.*]], 1.000000e+00 ; CHECK-NEXT: ret i1 [[CMP1]] ; %cmp1 = fcmp ord double %x, 0.000000e+00