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Recommit "[ConstraintElim] Simplify cmp after uadd.sat/usub.sat (#135603)" #136467

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Merged
merged 7 commits into from
Apr 30, 2025
Merged

Recommit "[ConstraintElim] Simplify cmp after uadd.sat/usub.sat (#135603)" #136467

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f4bf37b
[ConstraintElim] Fix poison check before adding intrinsic facts
el-ev Apr 18, 2025
66a876c
"Recommit "[ConstraintElim] Simplify cmp after uadd.sat/usub.sat (#13…
el-ev Apr 20, 2025
3e63609
Merge branch 'main' into users/el-ev/04-18-_constraintelim_fix_poison…
el-ev Apr 30, 2025
c3535a9
Merge branch 'users/el-ev/04-18-_constraintelim_fix_poison_check_befo…
el-ev Apr 30, 2025
4a30bfe
update
el-ev Apr 30, 2025
bf9f398
Merge branch 'users/el-ev/04-18-_constraintelim_fix_poison_check_befo…
el-ev Apr 30, 2025
bb5bcae
Merge branch 'main' into users/el-ev/04-20-_recommit_constraintelim_s…
el-ev Apr 30, 2025
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17 changes: 17 additions & 0 deletions llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1135,6 +1135,9 @@ void State::addInfoFor(BasicBlock &BB) {
// TODO: handle llvm.abs as well
WorkList.push_back(
FactOrCheck::getCheck(DT.getNode(&BB), cast<CallInst>(&I)));
[[fallthrough]];
case Intrinsic::uadd_sat:
case Intrinsic::usub_sat:
// TODO: Check if it is possible to instead only added the min/max facts
// when simplifying uses of the min/max intrinsics.
if (!isGuaranteedNotToBePoison(&I))
Expand Down Expand Up @@ -1896,6 +1899,20 @@ static bool eliminateConstraints(Function &F, DominatorTree &DT, LoopInfo &LI,
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;
Expand Down
7 changes: 2 additions & 5 deletions llvm/test/Transforms/ConstraintElimination/uadd-usub-sat.ll
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Expand Up @@ -8,9 +8,7 @@ define i1 @uadd_sat_uge(i64 noundef %a, i64 noundef %b) {
; CHECK-LABEL: define i1 @uadd_sat_uge(
; CHECK-SAME: i64 noundef [[A:%.*]], i64 noundef [[B:%.*]]) {
; CHECK-NEXT: [[ADD_SAT:%.*]] = call i64 @llvm.uadd.sat.i64(i64 [[A]], i64 [[B]])
; CHECK-NEXT: [[CMP1:%.*]] = icmp uge i64 [[ADD_SAT]], [[A]]
; CHECK-NEXT: [[CMP2:%.*]] = icmp uge i64 [[ADD_SAT]], [[B]]
; CHECK-NEXT: [[CMP:%.*]] = and i1 [[CMP1]], [[CMP2]]
; CHECK-NEXT: [[CMP:%.*]] = and i1 true, true
; CHECK-NEXT: ret i1 [[CMP]]
;
%add.sat = call i64 @llvm.uadd.sat.i64(i64 %a, i64 %b)
Expand All @@ -24,8 +22,7 @@ define i1 @usub_sat_ule_lhs(i64 noundef %a, i64 noundef %b) {
; CHECK-LABEL: define i1 @usub_sat_ule_lhs(
; CHECK-SAME: i64 noundef [[A:%.*]], i64 noundef [[B:%.*]]) {
; CHECK-NEXT: [[SUB_SAT:%.*]] = call i64 @llvm.usub.sat.i64(i64 [[A]], i64 [[B]])
; CHECK-NEXT: [[CMP:%.*]] = icmp ule i64 [[SUB_SAT]], [[A]]
; CHECK-NEXT: ret i1 [[CMP]]
; CHECK-NEXT: ret i1 true
;
%sub.sat = call i64 @llvm.usub.sat.i64(i64 %a, i64 %b)
%cmp = icmp ule i64 %sub.sat, %a
Expand Down
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