[CostModel][TTI] Replace BAD_ICMP_PREDICATE with ICMP_SGT for generic…

… sadd/ssub sat cost expansion The comparison always checks for negative values so know the icmp predicate will be ICMP_SGT
llvm · Oct 7, 2021 · 7168837 · 7168837
1 parent 5197520
commit 7168837
Show file tree

Hide file tree

Showing 2 changed files with 89 additions and 90 deletions.
diff --git a/llvm/include/llvm/CodeGen/BasicTTIImpl.h b/llvm/include/llvm/CodeGen/BasicTTIImpl.h
@@ -1724,19 +1724,18 @@ class BasicTTIImplBase : public TargetTransformInfoImplCRTPBase<T> {
       Intrinsic::ID OverflowOp = IID == Intrinsic::sadd_sat
                                      ? Intrinsic::sadd_with_overflow
                                      : Intrinsic::ssub_with_overflow;
+      CmpInst::Predicate Pred = CmpInst::ICMP_SGT;
 
       // SatMax -> Overflow && SumDiff < 0
       // SatMin -> Overflow && SumDiff >= 0
       InstructionCost Cost = 0;
       IntrinsicCostAttributes Attrs(OverflowOp, OpTy, {RetTy, RetTy}, FMF,
                                     nullptr, ScalarizationCostPassed);
       Cost += thisT()->getIntrinsicInstrCost(Attrs, CostKind);
-      Cost +=
-          thisT()->getCmpSelInstrCost(BinaryOperator::ICmp, RetTy, CondTy,
-                                      CmpInst::BAD_ICMP_PREDICATE, CostKind);
-      Cost += 2 * thisT()->getCmpSelInstrCost(
-                      BinaryOperator::Select, RetTy, CondTy,
-                      CmpInst::BAD_ICMP_PREDICATE, CostKind);
+      Cost += thisT()->getCmpSelInstrCost(BinaryOperator::ICmp, RetTy, CondTy,
+                                          Pred, CostKind);
+      Cost += 2 * thisT()->getCmpSelInstrCost(BinaryOperator::Select, RetTy,
+                                              CondTy, Pred, CostKind);
       return Cost;
     }
     case Intrinsic::uadd_sat: