[llvm] 345748e - [IVDescriptor] Explicitly check for isMinMaxRecurrenceKind in getReductionOpChain. NFC (#132025)

[via llvm-commits]

Author: Luke Lau
Date: 2025-03-20T21:22:55+08:00
New Revision: 345748e02722ce81ecd11beac18121b23325b853

URL: https://github.com/llvm/llvm-project/commit/345748e02722ce81ecd11beac18121b23325b853
DIFF: https://github.com/llvm/llvm-project/commit/345748e02722ce81ecd11beac18121b23325b853.diff

LOG: [IVDescriptor] Explicitly check for isMinMaxRecurrenceKind in getReductionOpChain. NFC (#132025)

There are other types of recurrences with an icmp/fcmp opcode, AnyOf and
FindLastIV, so don't rely on the opcode to detect them.
This makes adding support for AnyOf in #131830 easier.

Note that these currently fail the ExpectedUses/isCorrectOpcode checks
anyway, so there shouldn't be any functional change.

Added: 
    

Modified: 
    llvm/lib/Analysis/IVDescriptors.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/IVDescriptors.cpp b/llvm/lib/Analysis/IVDescriptors.cpp
index f74ede4450ce5..45b5b2979a562 100644
--- a/llvm/lib/Analysis/IVDescriptors.cpp
+++ b/llvm/lib/Analysis/IVDescriptors.cpp
@@ -1167,6 +1167,7 @@ SmallVector<Instruction *, 4>
 RecurrenceDescriptor::getReductionOpChain(PHINode *Phi, Loop *L) const {
   SmallVector<Instruction *, 4> ReductionOperations;
   unsigned RedOp = getOpcode();
+  const bool IsMinMax = isMinMaxRecurrenceKind(Kind);
 
   // Search down from the Phi to the LoopExitInstr, looking for instructions
   // with a single user of the correct type for the reduction.
@@ -1184,7 +1185,7 @@ RecurrenceDescriptor::getReductionOpChain(PHINode *Phi, Loop *L) const {
   // more expensive than out-of-loop reductions, and need to be costed more
   // carefully.
   unsigned ExpectedUses = 1;
-  if (RedOp == Instruction::ICmp || RedOp == Instruction::FCmp)
+  if (IsMinMax)
     ExpectedUses = 2;
 
   auto getNextInstruction = [&](Instruction *Cur) -> Instruction * {
@@ -1192,7 +1193,7 @@ RecurrenceDescriptor::getReductionOpChain(PHINode *Phi, Loop *L) const {
       Instruction *UI = cast<Instruction>(User);
       if (isa<PHINode>(UI))
         continue;
-      if (RedOp == Instruction::ICmp || RedOp == Instruction::FCmp) {
+      if (IsMinMax) {
         // We are expecting a icmp/select pair, which we go to the next select
         // instruction if we can. We already know that Cur has 2 uses.
         if (isa<SelectInst>(UI))
@@ -1204,7 +1205,7 @@ RecurrenceDescriptor::getReductionOpChain(PHINode *Phi, Loop *L) const {
     return nullptr;
   };
   auto isCorrectOpcode = [&](Instruction *Cur) {
-    if (RedOp == Instruction::ICmp || RedOp == Instruction::FCmp) {
+    if (IsMinMax) {
       Value *LHS, *RHS;
       return SelectPatternResult::isMinOrMax(
           matchSelectPattern(Cur, LHS, RHS).Flavor);