[PATCH] D43878: [LoopUnroll] Simplify induction variables after peeling too.

[Florian Hahn via Phabricator via llvm-commits]

fhahn created this revision.
fhahn added reviewers: sanjoy, bogner, mzolotukhin, efriedma.

Loop peeling also has an impact on the induction variables, so we should
benefit from induction variable simplification after peeling too.


https://reviews.llvm.org/D43878

Files:
  lib/Transforms/Utils/LoopUnroll.cpp
  test/Transforms/LoopUnroll/peel-loop-conditions.ll


Index: test/Transforms/LoopUnroll/peel-loop-conditions.ll
===================================================================
--- test/Transforms/LoopUnroll/peel-loop-conditions.ll
+++ test/Transforms/LoopUnroll/peel-loop-conditions.ll
@@ -33,17 +33,9 @@
 ; CHECK-NEXT:    [[CMP_PEEL8:%.*]] = icmp slt i32 [[INC_PEEL7]], [[K]]
 ; CHECK-NEXT:    br i1 [[CMP_PEEL8]], label [[FOR_BODY:%.*]], label [[FOR_END]]
 ; CHECK:       for.body:
-; CHECK-NEXT:    [[I_05:%.*]] = phi i32 [ [[INC:%.*]], [[FOR_INC:%.*]] ], [ [[INC_PEEL7]], [[FOR_INC_PEEL6]] ]
-; CHECK-NEXT:    [[CMP1:%.*]] = icmp ult i32 [[I_05]], 2
-; CHECK-NEXT:    br i1 [[CMP1]], label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
-; CHECK:       if.then:
-; CHECK-NEXT:    call void @f1()
-; CHECK-NEXT:    br label [[FOR_INC]]
-; CHECK:       if.else:
+; CHECK-NEXT:    [[I_05:%.*]] = phi i32 [ [[INC:%.*]], [[FOR_BODY]] ], [ [[INC_PEEL7]], [[FOR_INC_PEEL6]] ]
 ; CHECK-NEXT:    call void @f2()
-; CHECK-NEXT:    br label [[FOR_INC]]
-; CHECK:       for.inc:
-; CHECK-NEXT:    [[INC]] = add nsw i32 [[I_05]], 1
+; CHECK-NEXT:    [[INC]] = add nuw nsw i32 [[I_05]], 1
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[INC]], [[K]]
 ; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END]], !llvm.loop !0
 ; CHECK:       for.end:
Index: lib/Transforms/Utils/LoopUnroll.cpp
===================================================================
--- lib/Transforms/Utils/LoopUnroll.cpp
+++ lib/Transforms/Utils/LoopUnroll.cpp
@@ -403,8 +403,9 @@
          "Did not expect runtime trip-count unrolling "
          "and peeling for the same loop");
 
+  bool Peeled = false;
   if (PeelCount) {
-    bool Peeled = peelLoop(L, PeelCount, LI, SE, DT, AC, PreserveLCSSA);
+    Peeled = peelLoop(L, PeelCount, LI, SE, DT, AC, PreserveLCSSA);
 
     // Successful peeling may result in a change in the loop preheader/trip
     // counts. If we later unroll the loop, we want these to be updated.
@@ -790,7 +791,7 @@
   }
 
   // Simplify any new induction variables in the partially unrolled loop.
-  if (SE && !CompletelyUnroll && Count > 1) {
+  if (SE && !CompletelyUnroll && (Count > 1 || Peeled)) {
     SmallVector<WeakTrackingVH, 16> DeadInsts;
     simplifyLoopIVs(L, SE, DT, LI, DeadInsts);
 


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D43878.136322.patch
Type: text/x-patch
Size: 2252 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20180228/ec439257/attachment.bin>