[llvm] 3356eb3 - [llvm-reduce] Reduce samesign flag from icmp (#115492)

[via llvm-commits]

Author: Yingwei Zheng
Date: 2024-11-09T00:12:09+08:00
New Revision: 3356eb3b15f391b9b4f62b0157fede16bd8cd5b3

URL: https://github.com/llvm/llvm-project/commit/3356eb3b15f391b9b4f62b0157fede16bd8cd5b3
DIFF: https://github.com/llvm/llvm-project/commit/3356eb3b15f391b9b4f62b0157fede16bd8cd5b3.diff

LOG: [llvm-reduce] Reduce samesign flag from icmp (#115492)

Added: 
    

Modified: 
    llvm/test/tools/llvm-reduce/reduce-flags.ll
    llvm/tools/llvm-reduce/deltas/ReduceInstructionFlags.cpp

Removed: 
    


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diff  --git a/llvm/test/tools/llvm-reduce/reduce-flags.ll b/llvm/test/tools/llvm-reduce/reduce-flags.ll
index 293504e32f9108..f220fc429c89e9 100644
--- a/llvm/test/tools/llvm-reduce/reduce-flags.ll
+++ b/llvm/test/tools/llvm-reduce/reduce-flags.ll
@@ -272,3 +272,19 @@ define i32 @trunc_nsw_keep(i64 %a) {
   %op = trunc nsw i64 %a to i32
   ret i32 %op
 }
+
+; CHECK-LABEL: @icmp_samesign_drop(
+; INTERESTING: = icmp
+; RESULT: icmp ult i32
+define i1 @icmp_samesign_drop(i32 %a) {
+  %op = icmp samesign ult i32 %a, 10
+  ret i1 %op
+}
+
+; CHECK-LABEL: @icmp_samesign_keep(
+; INTERESTING: = icmp samesign
+; RESULT: icmp samesign ult i32
+define i1 @icmp_samesign_keep(i32 %a) {
+  %op = icmp samesign ult i32 %a, 10
+  ret i1 %op
+}

diff  --git a/llvm/tools/llvm-reduce/deltas/ReduceInstructionFlags.cpp b/llvm/tools/llvm-reduce/deltas/ReduceInstructionFlags.cpp
index ff9dde40b2df41..e157747004782d 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceInstructionFlags.cpp
+++ b/llvm/tools/llvm-reduce/deltas/ReduceInstructionFlags.cpp
@@ -42,6 +42,9 @@ static void reduceFlagsInModule(Oracle &O, ReducerWorkItem &WorkItem) {
       } else if (auto *PDI = dyn_cast<PossiblyDisjointInst>(&I)) {
         if (PDI->isDisjoint() && !O.shouldKeep())
           PDI->setIsDisjoint(false);
+      } else if (auto *ICmp = dyn_cast<ICmpInst>(&I)) {
+        if (ICmp->hasSameSign() && !O.shouldKeep())
+          ICmp->setSameSign(false);
       } else if (auto *GEP = dyn_cast<GetElementPtrInst>(&I)) {
         GEPNoWrapFlags NW = GEP->getNoWrapFlags();
         if (NW.isInBounds() && !O.shouldKeep())