[llvm] r328301 - [LoopUnroll] Simplify induction variables after peeling too.

Florian Hahn via llvm-commits llvm-commits at lists.llvm.org
Fri Mar 23 03:38:12 PDT 2018 

Author: fhahn
Date: Fri Mar 23 03:38:12 2018
New Revision: 328301

URL: http://llvm.org/viewvc/llvm-project?rev=328301&view=rev
Log:
[LoopUnroll] Simplify induction variables after peeling too.

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

Reviewers: sanjoy, bogner, mzolotukhin, efriedma

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D43878

Modified:
    llvm/trunk/lib/Transforms/Utils/LoopUnroll.cpp
    llvm/trunk/test/Transforms/LoopUnroll/peel-loop-conditions.ll

Modified: llvm/trunk/lib/Transforms/Utils/LoopUnroll.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/LoopUnroll.cpp?rev=328301&r1=328300&r2=328301&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/LoopUnroll.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/LoopUnroll.cpp Fri Mar 23 03:38:12 2018
@@ -403,8 +403,9 @@ LoopUnrollResult llvm::UnrollLoop(
          "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 @@ LoopUnrollResult llvm::UnrollLoop(
   }
 
   // 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);
 

Modified: llvm/trunk/test/Transforms/LoopUnroll/peel-loop-conditions.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopUnroll/peel-loop-conditions.ll?rev=328301&r1=328300&r2=328301&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/LoopUnroll/peel-loop-conditions.ll (original)
+++ llvm/trunk/test/Transforms/LoopUnroll/peel-loop-conditions.ll Fri Mar 23 03:38:12 2018
@@ -47,8 +47,7 @@ define void @test1(i32 %k) {
 ; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
 ; CHECK:       for.body:
 ; CHECK-NEXT:    [[I_05:%.*]] = phi i32 [ [[INC_PEEL7]], [[FOR_BODY_LR_PH_PEEL_NEWPH]] ], [ [[INC:%.*]], [[FOR_INC:%.*]] ]
-; CHECK-NEXT:    [[CMP1:%.*]] = icmp ult i32 [[I_05]], 2
-; CHECK-NEXT:    br i1 [[CMP1]], label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
+; CHECK-NEXT:    br i1 false, label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
 ; CHECK:       if.then:
 ; CHECK-NEXT:    call void @f1()
 ; CHECK-NEXT:    br label [[FOR_INC]]
@@ -56,7 +55,7 @@ define void @test1(i32 %k) {
 ; 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_LOOPEXIT:%.*]], !llvm.loop !0
 ; CHECK:       for.end.loopexit:
@@ -186,8 +185,7 @@ define void @test2(i32 %k) {
 ; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
 ; CHECK:       for.body:
 ; CHECK-NEXT:    [[I_05:%.*]] = phi i32 [ [[INC_PEEL32]], [[FOR_BODY_LR_PH_PEEL_NEWPH]] ], [ [[INC:%.*]], [[FOR_INC:%.*]] ]
-; CHECK-NEXT:    [[CMP1:%.*]] = icmp ult i32 [[I_05]], 2
-; CHECK-NEXT:    br i1 [[CMP1]], label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
+; CHECK-NEXT:    br i1 false, label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
 ; CHECK:       if.then:
 ; CHECK-NEXT:    call void @f1()
 ; CHECK-NEXT:    br label [[IF2:%.*]]
@@ -195,13 +193,12 @@ define void @test2(i32 %k) {
 ; CHECK-NEXT:    call void @f2()
 ; CHECK-NEXT:    br label [[IF2]]
 ; CHECK:       if2:
-; CHECK-NEXT:    [[CMP2:%.*]] = icmp ult i32 [[I_05]], 4
-; CHECK-NEXT:    br i1 [[CMP2]], label [[IF_THEN2:%.*]], label [[FOR_INC]]
+; CHECK-NEXT:    br i1 false, label [[IF_THEN2:%.*]], label [[FOR_INC]]
 ; CHECK:       if.then2:
 ; CHECK-NEXT:    call void @f1()
 ; 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_LOOPEXIT:%.*]], !llvm.loop !2
 ; CHECK:       for.end.loopexit:
@@ -300,8 +297,7 @@ define void @test3(i32 %k) {
 ; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
 ; CHECK:       for.body:
 ; CHECK-NEXT:    [[I_05:%.*]] = phi i32 [ [[INC_PEEL15]], [[FOR_BODY_LR_PH_PEEL_NEWPH]] ], [ [[INC:%.*]], [[FOR_INC:%.*]] ]
-; CHECK-NEXT:    [[CMP1:%.*]] = icmp ugt i32 [[I_05]], 2
-; CHECK-NEXT:    br i1 [[CMP1]], label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
+; CHECK-NEXT:    br i1 true, label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
 ; CHECK:       if.then:
 ; CHECK-NEXT:    call void @f1()
 ; CHECK-NEXT:    br label [[FOR_INC]]
@@ -309,7 +305,7 @@ define void @test3(i32 %k) {
 ; 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_LOOPEXIT:%.*]], !llvm.loop !3
 ; CHECK:       for.end.loopexit:
@@ -445,7 +441,7 @@ define void @test4(i32 %k) {
 ; CHECK-NEXT:    call void @f1()
 ; 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_LOOPEXIT:%.*]], !llvm.loop !4
 ; CHECK:       for.end.loopexit:
@@ -568,8 +564,7 @@ define void @test6(i32 %k) {
 ; CHECK:       for.body:
 ; CHECK-NEXT:    [[I_05:%.*]] = phi i32 [ [[INC_PEEL]], [[ENTRY_PEEL_NEWPH]] ], [ [[INC:%.*]], [[FOR_INC:%.*]] ]
 ; CHECK-NEXT:    [[J:%.*]] = phi i32 [ [[INC_PEEL]], [[ENTRY_PEEL_NEWPH]] ], [ [[INC]], [[FOR_INC]] ]
-; CHECK-NEXT:    [[CMP1:%.*]] = icmp ult i32 [[I_05]], [[J]]
-; CHECK-NEXT:    br i1 [[CMP1]], label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
+; CHECK-NEXT:    br i1 false, label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
 ; CHECK:       if.then:
 ; CHECK-NEXT:    call void @f1()
 ; CHECK-NEXT:    br label [[FOR_INC]]
@@ -577,7 +572,7 @@ define void @test6(i32 %k) {
 ; CHECK-NEXT:    call void @f2()
 ; CHECK-NEXT:    br label [[FOR_INC]]
 ; CHECK:       for.inc:
-; CHECK-NEXT:    [[INC]] = add nsw i32 [[I_05]], 2
+; CHECK-NEXT:    [[INC]] = add nuw nsw i32 [[I_05]], 2
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[INC]], [[K]]
 ; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END_LOOPEXIT:%.*]], !llvm.loop !5
 ; CHECK:       for.end.loopexit:

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