[PATCH] D138404: [LoopFlatten] Fix IV increment use count

[Dave Green via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rG8e9e22f07bcb: [LoopFlatten] Fix IV increment use count (authored by dmgreen).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D138404/new/

https://reviews.llvm.org/D138404

Files:
  llvm/lib/Transforms/Scalar/LoopFlatten.cpp
  llvm/test/Transforms/LoopFlatten/widen-pr58441.ll


Index: llvm/test/Transforms/LoopFlatten/widen-pr58441.ll
===================================================================
--- llvm/test/Transforms/LoopFlatten/widen-pr58441.ll
+++ llvm/test/Transforms/LoopFlatten/widen-pr58441.ll
@@ -8,27 +8,22 @@
 define i32 @test() {
 ; CHECK-LABEL: @test(
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[FLATTEN_TRIPCOUNT:%.*]] = mul i64 6, 6
 ; CHECK-NEXT:    br label [[FOR_COND1_PREHEADER_I:%.*]]
 ; CHECK:       for.cond1.preheader.i:
-; CHECK-NEXT:    [[INDVAR1:%.*]] = phi i64 [ [[INDVAR_NEXT2:%.*]], [[FOR_INC5_I:%.*]] ], [ 0, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[L_011_I:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[ADD6_I:%.*]], [[FOR_INC5_I:%.*]] ]
 ; CHECK-NEXT:    br label [[WHILE_COND_I_PREHEADER_I:%.*]]
 ; CHECK:       while.cond.i.preheader.i:
-; CHECK-NEXT:    [[INDVAR:%.*]] = phi i64 [ 0, [[FOR_COND1_PREHEADER_I]] ]
-; CHECK-NEXT:    [[STOREMERGE9_I:%.*]] = phi i32 [ 0, [[FOR_COND1_PREHEADER_I]] ]
-; CHECK-NEXT:    [[INDVAR_NEXT:%.*]] = add i64 [[INDVAR]], 1
-; CHECK-NEXT:    [[ADD_I:%.*]] = add nuw nsw i32 [[STOREMERGE9_I]], 1
-; CHECK-NEXT:    [[CMP2_I:%.*]] = icmp ult i64 [[INDVAR]], 5
-; CHECK-NEXT:    br label [[FOR_INC5_I]]
+; CHECK-NEXT:    [[STOREMERGE9_I:%.*]] = phi i32 [ 0, [[FOR_COND1_PREHEADER_I]] ], [ [[ADD_I:%.*]], [[WHILE_COND_I_PREHEADER_I]] ]
+; CHECK-NEXT:    [[ADD_I]] = add nuw nsw i32 [[STOREMERGE9_I]], 1
+; CHECK-NEXT:    [[CMP2_I:%.*]] = icmp ult i32 [[STOREMERGE9_I]], 5
+; CHECK-NEXT:    br i1 [[CMP2_I]], label [[WHILE_COND_I_PREHEADER_I]], label [[FOR_INC5_I]]
 ; CHECK:       for.inc5.i:
-; CHECK-NEXT:    [[ADD_I_LCSSA_WIDE:%.*]] = phi i64 [ [[INDVAR_NEXT]], [[WHILE_COND_I_PREHEADER_I]] ]
 ; CHECK-NEXT:    [[ADD_I_LCSSA:%.*]] = phi i32 [ [[ADD_I]], [[WHILE_COND_I_PREHEADER_I]] ]
-; CHECK-NEXT:    [[TMP0:%.*]] = trunc i64 [[ADD_I_LCSSA_WIDE]] to i32
-; CHECK-NEXT:    [[INDVAR_NEXT2]] = add i64 [[INDVAR1]], 1
-; CHECK-NEXT:    [[EXITCOND_NOT_I:%.*]] = icmp eq i64 [[INDVAR_NEXT2]], [[FLATTEN_TRIPCOUNT]]
+; CHECK-NEXT:    [[ADD6_I]] = add nuw nsw i32 [[L_011_I]], 1
+; CHECK-NEXT:    [[EXITCOND_NOT_I:%.*]] = icmp eq i32 [[ADD6_I]], 6
 ; CHECK-NEXT:    br i1 [[EXITCOND_NOT_I]], label [[E_EXIT:%.*]], label [[FOR_COND1_PREHEADER_I]]
 ; CHECK:       e.exit:
-; CHECK-NEXT:    [[ADD_I_LCSSA_LCSSA:%.*]] = phi i32 [ [[TMP0]], [[FOR_INC5_I]] ]
+; CHECK-NEXT:    [[ADD_I_LCSSA_LCSSA:%.*]] = phi i32 [ [[ADD_I_LCSSA]], [[FOR_INC5_I]] ]
 ; CHECK-NEXT:    ret i32 [[ADD_I_LCSSA_LCSSA]]
 ;
 entry:
@@ -59,21 +54,20 @@
 define i32 @test64() {
 ; CHECK-LABEL: @test64(
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[FLATTEN_TRIPCOUNT:%.*]] = mul i64 6, 6
 ; CHECK-NEXT:    br label [[FOR_COND1_PREHEADER_I:%.*]]
 ; CHECK:       for.cond1.preheader.i:
 ; CHECK-NEXT:    [[L_011_I:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[ADD6_I:%.*]], [[FOR_INC5_I:%.*]] ]
 ; CHECK-NEXT:    br label [[WHILE_COND_I_PREHEADER_I:%.*]]
 ; CHECK:       while.cond.i.preheader.i:
-; CHECK-NEXT:    [[STOREMERGE9_I:%.*]] = phi i64 [ 0, [[FOR_COND1_PREHEADER_I]] ]
-; CHECK-NEXT:    [[ADD_I:%.*]] = add nuw nsw i64 [[STOREMERGE9_I]], 1
+; CHECK-NEXT:    [[STOREMERGE9_I:%.*]] = phi i64 [ 0, [[FOR_COND1_PREHEADER_I]] ], [ [[ADD_I:%.*]], [[WHILE_COND_I_PREHEADER_I]] ]
+; CHECK-NEXT:    [[ADD_I]] = add nuw nsw i64 [[STOREMERGE9_I]], 1
 ; CHECK-NEXT:    [[CMP2_I:%.*]] = icmp ult i64 [[STOREMERGE9_I]], 5
-; CHECK-NEXT:    br label [[FOR_INC5_I]]
+; CHECK-NEXT:    br i1 [[CMP2_I]], label [[WHILE_COND_I_PREHEADER_I]], label [[FOR_INC5_I]]
 ; CHECK:       for.inc5.i:
 ; CHECK-NEXT:    [[ADD_I_LCSSA_WIDEN:%.*]] = phi i64 [ [[ADD_I]], [[WHILE_COND_I_PREHEADER_I]] ]
 ; CHECK-NEXT:    [[ADD_I_LCSSA:%.*]] = trunc i64 [[ADD_I_LCSSA_WIDEN]] to i32
 ; CHECK-NEXT:    [[ADD6_I]] = add nuw nsw i64 [[L_011_I]], 1
-; CHECK-NEXT:    [[EXITCOND_NOT_I:%.*]] = icmp eq i64 [[ADD6_I]], [[FLATTEN_TRIPCOUNT]]
+; CHECK-NEXT:    [[EXITCOND_NOT_I:%.*]] = icmp eq i64 [[ADD6_I]], 6
 ; CHECK-NEXT:    br i1 [[EXITCOND_NOT_I]], label [[E_EXIT:%.*]], label [[FOR_COND1_PREHEADER_I]]
 ; CHECK:       e.exit:
 ; CHECK-NEXT:    [[ADD_I_LCSSA_LCSSA:%.*]] = phi i32 [ [[ADD_I_LCSSA]], [[FOR_INC5_I]] ]
Index: llvm/lib/Transforms/Scalar/LoopFlatten.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/LoopFlatten.cpp
+++ llvm/lib/Transforms/Scalar/LoopFlatten.cpp
@@ -413,7 +413,8 @@
   // increment variable.
   Increment =
       cast<BinaryOperator>(InductionPHI->getIncomingValueForBlock(Latch));
-  if (Increment->hasNUsesOrMore(3)) {
+  if ((Compare->getOperand(0) != Increment || !Increment->hasNUses(2)) &&
+      !Increment->hasNUses(1)) {
     LLVM_DEBUG(dbgs() << "Could not find valid increment\n");
     return false;
   }


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