[LV] Add support for minimum/maximum intrinsics

{mini|maxi}mum intrinsics are different from {min|max}num intrinsics in
the propagation of NaN and signed zero. Also, the minnum/maxnum
intrinsics require the presence of nsz flags to be valid reductions in
vectorizer. In this regard, we introduce a new recurrence kind and also
add support for identifying reduction patterns using these intrinsics.

The reduction intrinsics and lowering was introduced here: 26bfbec5d2.

There are tests added which show how this interacts across chains of
min/max patterns.

Differential Revision: https://reviews.llvm.org/D151482

1 files changed, 13 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Utils/LoopUtils.cpp b/llvm/lib/Transforms/Utils/LoopUtils.cpp
index 90c9396..2dfaea7 100644
--- a/llvm/lib/Transforms/Utils/LoopUtils.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUtils.cpp
@@ -909,6 +909,10 @@ Intrinsic::ID llvm::getMinMaxReductionIntrinsicOp(RecurKind RK) {
     return Intrinsic::minnum;
   case RecurKind::FMax:
     return Intrinsic::maxnum;
+  case RecurKind::FMinimum:
+    return Intrinsic::minimum;
+  case RecurKind::FMaximum:
+    return Intrinsic::maximum;
   }
 }
 
@@ -928,6 +932,9 @@ CmpInst::Predicate llvm::getMinMaxReductionPredicate(RecurKind RK) {
     return CmpInst::FCMP_OLT;
   case RecurKind::FMax:
     return CmpInst::FCMP_OGT;
+  // We do not add FMinimum/FMaximum recurrence kind here since there is no
+  // equivalent predicate which compares signed zeroes according to the
+  // semantics of the intrinsics (llvm.minimum/maximum).
   }
 }
 
@@ -943,7 +950,8 @@ Value *llvm::createSelectCmpOp(IRBuilderBase &Builder, Value *StartVal,
 Value *llvm::createMinMaxOp(IRBuilderBase &Builder, RecurKind RK, Value *Left,
                             Value *Right) {
   Type *Ty = Left->getType();
-  if (Ty->isIntOrIntVectorTy()) {
+  if (Ty->isIntOrIntVectorTy() ||
+      (RK == RecurKind::FMinimum || RK == RecurKind::FMaximum)) {
     // TODO: Add float minnum/maxnum support when FMF nnan is set.
     Intrinsic::ID Id = getMinMaxReductionIntrinsicOp(RK);
     return Builder.CreateIntrinsic(Ty, Id, {Left, Right}, nullptr,
@@ -1094,6 +1102,10 @@ Value *llvm::createSimpleTargetReduction(IRBuilderBase &Builder,
     return Builder.CreateFPMaxReduce(Src);
   case RecurKind::FMin:
     return Builder.CreateFPMinReduce(Src);
+  case RecurKind::FMinimum:
+    return Builder.CreateFPMinimumReduce(Src);
+  case RecurKind::FMaximum:
+    return Builder.CreateFPMaximumReduce(Src);
   default:
     llvm_unreachable("Unhandled opcode");
   }