[llvm] be9f72c - Revert "[ConstraintElim] Simplify cmp after uadd.sat/usub.sat (#135603)"

[Arthur Eubanks via llvm-commits]

Author: Arthur Eubanks
Date: 2025-04-18T15:37:37Z
New Revision: be9f72cf3716bc1de5912a457284a1973112f9a0

URL: https://github.com/llvm/llvm-project/commit/be9f72cf3716bc1de5912a457284a1973112f9a0
DIFF: https://github.com/llvm/llvm-project/commit/be9f72cf3716bc1de5912a457284a1973112f9a0.diff

LOG: Revert "[ConstraintElim] Simplify cmp after uadd.sat/usub.sat (#135603)"

This reverts commit fe54d1afcca055f464840654dd2ec3fd83aea688.

Causes miscompiles, see #135603.

Added: 
    

Modified: 
    llvm/lib/Transforms/Scalar/ConstraintElimination.cpp

Removed: 
    llvm/test/Transforms/ConstraintElimination/uadd-usub-sat.ll


################################################################################
diff  --git a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
index 31e057baee2bf..2604bb9153f17 100644
--- a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
@@ -1141,8 +1141,6 @@ void State::addInfoFor(BasicBlock &BB) {
         break;
       [[fallthrough]];
     case Intrinsic::abs:
-    case Intrinsic::uadd_sat:
-    case Intrinsic::usub_sat:
       WorkList.push_back(FactOrCheck::getInstFact(DT.getNode(&BB), &I));
       break;
     }
@@ -1893,26 +1891,13 @@ static bool eliminateConstraints(Function &F, DominatorTree &DT, LoopInfo &LI,
         AddFact(CmpInst::ICMP_SGE, CB.Inst, X);
         continue;
       }
+
       if (auto *MinMax = dyn_cast<MinMaxIntrinsic>(CB.Inst)) {
         Pred = ICmpInst::getNonStrictPredicate(MinMax->getPredicate());
         AddFact(Pred, MinMax, MinMax->getLHS());
         AddFact(Pred, MinMax, MinMax->getRHS());
         continue;
       }
-      if (auto *USatI = dyn_cast<SaturatingInst>(CB.Inst)) {
-        switch (USatI->getIntrinsicID()) {
-        default:
-          llvm_unreachable("Unexpected intrinsic.");
-        case Intrinsic::uadd_sat:
-          AddFact(ICmpInst::ICMP_UGE, USatI, USatI->getLHS());
-          AddFact(ICmpInst::ICMP_UGE, USatI, USatI->getRHS());
-          break;
-        case Intrinsic::usub_sat:
-          AddFact(ICmpInst::ICMP_ULE, USatI, USatI->getLHS());
-          break;
-        }
-        continue;
-      }
     }
 
     Value *A = nullptr, *B = nullptr;

diff  --git a/llvm/test/Transforms/ConstraintElimination/uadd-usub-sat.ll b/llvm/test/Transforms/ConstraintElimination/uadd-usub-sat.ll
deleted file mode 100644
index b0db89dcfdab8..0000000000000
--- a/llvm/test/Transforms/ConstraintElimination/uadd-usub-sat.ll
+++ /dev/null
@@ -1,43 +0,0 @@
-; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
-; RUN: opt -passes=constraint-elimination -S %s | FileCheck %s
-
-declare i64 @llvm.uadd.sat.i64(i64, i64)
-declare i64 @llvm.usub.sat.i64(i64, i64)
-
-define i1 @uadd_sat_uge(i64 %a, i64 %b) {
-; CHECK-LABEL: define i1 @uadd_sat_uge(
-; CHECK-SAME: i64 [[A:%.*]], i64 [[B:%.*]]) {
-; CHECK-NEXT:    [[ADD_SAT:%.*]] = call i64 @llvm.uadd.sat.i64(i64 [[A]], i64 [[B]])
-; CHECK-NEXT:    [[CMP:%.*]] = and i1 true, true
-; CHECK-NEXT:    ret i1 [[CMP]]
-;
-  %add.sat = call i64 @llvm.uadd.sat.i64(i64 %a, i64 %b)
-  %cmp1 = icmp uge i64 %add.sat, %a
-  %cmp2 = icmp uge i64 %add.sat, %b
-  %cmp = and i1 %cmp1, %cmp2
-  ret i1 %cmp
-}
-
-define i1 @usub_sat_ule_lhs(i64 %a, i64 %b) {
-; CHECK-LABEL: define i1 @usub_sat_ule_lhs(
-; CHECK-SAME: i64 [[A:%.*]], i64 [[B:%.*]]) {
-; CHECK-NEXT:    [[SUB_SAT:%.*]] = call i64 @llvm.usub.sat.i64(i64 [[A]], i64 [[B]])
-; CHECK-NEXT:    ret i1 true
-;
-  %sub.sat = call i64 @llvm.usub.sat.i64(i64 %a, i64 %b)
-  %cmp = icmp ule i64 %sub.sat, %a
-  ret i1 %cmp
-}
-
-; Negative test
-define i1 @usub_sat_not_ule_rhs(i64 %a, i64 %b) {
-; CHECK-LABEL: define i1 @usub_sat_not_ule_rhs(
-; CHECK-SAME: i64 [[A:%.*]], i64 [[B:%.*]]) {
-; CHECK-NEXT:    [[SUB_SAT:%.*]] = call i64 @llvm.usub.sat.i64(i64 [[A]], i64 [[B]])
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ule i64 [[SUB_SAT]], [[B]]
-; CHECK-NEXT:    ret i1 [[CMP]]
-;
-  %sub.sat = call i64 @llvm.usub.sat.i64(i64 %a, i64 %b)
-  %cmp = icmp ule i64 %sub.sat, %b
-  ret i1 %cmp
-}