[llvm] 0bc3e23 - [InstCombine] Remove SPF factorizeMinMaxTree() (NFC)

[Nikita Popov via llvm-commits]

Author: Nikita Popov
Date: 2022-02-28T10:22:05+01:00
New Revision: 0bc3e233d74bfe2f6df47719cccb1662becc5c29

URL: https://github.com/llvm/llvm-project/commit/0bc3e233d74bfe2f6df47719cccb1662becc5c29
DIFF: https://github.com/llvm/llvm-project/commit/0bc3e233d74bfe2f6df47719cccb1662becc5c29.diff

LOG: [InstCombine] Remove SPF factorizeMinMaxTree() (NFC)

SPF integer min/max is canonicalized to min/max intrinsics before
this code is reached, so this should be entirely NFC.

Added: 
    

Modified: 
    llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
index 808cdc08f50ea..47bc45c101345 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -2317,63 +2317,6 @@ Instruction *InstCombinerImpl::matchSAddSubSat(Instruction &MinMax1) {
   return CastInst::Create(Instruction::SExt, Sat, Ty);
 }
 
-/// Reduce a sequence of min/max with a common operand.
-static Instruction *factorizeMinMaxTree(SelectPatternFlavor SPF, Value *LHS,
-                                        Value *RHS,
-                                        InstCombiner::BuilderTy &Builder) {
-  assert(SelectPatternResult::isMinOrMax(SPF) && "Expected a min/max");
-  // TODO: Allow FP min/max with nnan/nsz.
-  if (!LHS->getType()->isIntOrIntVectorTy())
-    return nullptr;
-
-  // Match 3 of the same min/max ops. Example: umin(umin(), umin()).
-  Value *A, *B, *C, *D;
-  SelectPatternResult L = matchSelectPattern(LHS, A, B);
-  SelectPatternResult R = matchSelectPattern(RHS, C, D);
-  if (SPF != L.Flavor || L.Flavor != R.Flavor)
-    return nullptr;
-
-  // Look for a common operand. The use checks are 
diff erent than usual because
-  // a min/max pattern typically has 2 uses of each op: 1 by the cmp and 1 by
-  // the select.
-  Value *MinMaxOp = nullptr;
-  Value *ThirdOp = nullptr;
-  if (!LHS->hasNUsesOrMore(3) && RHS->hasNUsesOrMore(3)) {
-    // If the LHS is only used in this chain and the RHS is used outside of it,
-    // reuse the RHS min/max because that will eliminate the LHS.
-    if (D == A || C == A) {
-      // min(min(a, b), min(c, a)) --> min(min(c, a), b)
-      // min(min(a, b), min(a, d)) --> min(min(a, d), b)
-      MinMaxOp = RHS;
-      ThirdOp = B;
-    } else if (D == B || C == B) {
-      // min(min(a, b), min(c, b)) --> min(min(c, b), a)
-      // min(min(a, b), min(b, d)) --> min(min(b, d), a)
-      MinMaxOp = RHS;
-      ThirdOp = A;
-    }
-  } else if (!RHS->hasNUsesOrMore(3)) {
-    // Reuse the LHS. This will eliminate the RHS.
-    if (D == A || D == B) {
-      // min(min(a, b), min(c, a)) --> min(min(a, b), c)
-      // min(min(a, b), min(c, b)) --> min(min(a, b), c)
-      MinMaxOp = LHS;
-      ThirdOp = C;
-    } else if (C == A || C == B) {
-      // min(min(a, b), min(b, d)) --> min(min(a, b), d)
-      // min(min(a, b), min(c, b)) --> min(min(a, b), d)
-      MinMaxOp = LHS;
-      ThirdOp = D;
-    }
-  }
-  if (!MinMaxOp || !ThirdOp)
-    return nullptr;
-
-  CmpInst::Predicate P = getMinMaxPred(SPF);
-  Value *CmpABC = Builder.CreateICmp(P, MinMaxOp, ThirdOp);
-  return SelectInst::Create(CmpABC, MinMaxOp, ThirdOp);
-}
-
 /// Try to reduce a funnel/rotate pattern that includes a compare and select
 /// into a funnel shift intrinsic. Example:
 /// rotl32(a, b) --> (b == 0 ? a : ((a >> (32 - b)) | (a << b)))
@@ -3117,8 +3060,6 @@ Instruction *InstCombinerImpl::visitSelectInst(SelectInst &SI) {
       if (Instruction *I = moveAddAfterMinMax(SPF, LHS, RHS, Builder))
         return I;
 
-      if (Instruction *I = factorizeMinMaxTree(SPF, LHS, RHS, Builder))
-        return I;
       if (Instruction *I = matchSAddSubSat(SI))
         return I;
     }