[PATCH] D106843: [IVDescriptors] Fix bug in checkOrderedReduction

[Anna Thomas via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rG68ffed12b7e2: [IVDescriptors] Fix bug in checkOrderedReduction (authored by anna).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D106843/new/

https://reviews.llvm.org/D106843

Files:
  llvm/lib/Analysis/IVDescriptors.cpp
  llvm/test/Transforms/LoopVectorize/fp-reduction-crash.ll


Index: llvm/test/Transforms/LoopVectorize/fp-reduction-crash.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/LoopVectorize/fp-reduction-crash.ll
@@ -0,0 +1,21 @@
+; REQUIRES: asserts
+; RUN: opt < %s -loop-vectorize -S | FileCheck %s
+
+; CHECK-LABEL: quux
+define void @quux() {
+bb:
+  br label %bb4
+
+bb1:                                              ; preds = %bb4
+  %tmp = phi double [ %tmp6, %bb4 ]
+  br i1 undef, label %bb4, label %bb2
+
+bb2:                                              ; preds = %bb1
+  %tmp3 = phi double [ %tmp, %bb1 ]
+  ret void
+
+bb4:                                              ; preds = %bb1, %bb
+  %tmp5 = phi double [ 1.300000e+01, %bb ], [ %tmp, %bb1 ]
+  %tmp6 = fadd double %tmp5, 1.000000e+00
+  br label %bb1
+}
Index: llvm/lib/Analysis/IVDescriptors.cpp
===================================================================
--- llvm/lib/Analysis/IVDescriptors.cpp
+++ llvm/lib/Analysis/IVDescriptors.cpp
@@ -199,16 +199,14 @@
   if (Kind != RecurKind::FAdd)
     return false;
 
-  bool IsOrdered =
-      Exit->getOpcode() == Instruction::FAdd && Exit == ExactFPMathInst;
+  if (Exit->getOpcode() != Instruction::FAdd || Exit != ExactFPMathInst)
+    return false;
 
   // The only pattern accepted is the one in which the reduction PHI
   // is used as one of the operands of the exit instruction
   auto *LHS = Exit->getOperand(0);
   auto *RHS = Exit->getOperand(1);
-  IsOrdered &= ((LHS == Phi) || (RHS == Phi));
-
-  if (!IsOrdered)
+  if (LHS != Phi && RHS != Phi)
     return false;
 
   LLVM_DEBUG(dbgs() << "LV: Found an ordered reduction: Phi: " << *Phi


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