[llvm] r329395 - [LoopUnroll] Make LoopPeeling respect the AllowPeeling preference.

[Chad Rosier via llvm-commits]

Author: mcrosier
Date: Fri Apr  6 06:57:21 2018
New Revision: 329395

URL: http://llvm.org/viewvc/llvm-project?rev=329395&view=rev
Log:
[LoopUnroll] Make LoopPeeling respect the AllowPeeling preference.

The SimpleLoopUnrollPass isn't suppose to perform loop peeling.

Differential Revision: https://reviews.llvm.org/D45334

Modified:
    llvm/trunk/lib/Transforms/Utils/LoopUnrollPeel.cpp
    llvm/trunk/test/Transforms/LoopUnroll/peel-loop-not-forced.ll

Modified: llvm/trunk/lib/Transforms/Utils/LoopUnrollPeel.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/LoopUnrollPeel.cpp?rev=329395&r1=329394&r2=329395&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/LoopUnrollPeel.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/LoopUnrollPeel.cpp Fri Apr  6 06:57:21 2018
@@ -232,6 +232,19 @@ void llvm::computePeelCount(Loop *L, uns
   if (!L->empty())
     return;
 
+  // If the user provided a peel count, use that.
+  bool UserPeelCount = UnrollForcePeelCount.getNumOccurrences() > 0;
+  if (UserPeelCount) {
+    DEBUG(dbgs() << "Force-peeling first " << UnrollForcePeelCount
+                 << " iterations.\n");
+    UP.PeelCount = UnrollForcePeelCount;
+    return;
+  }
+
+  // Skip peeling if it's disabled.
+  if (!UP.AllowPeeling)
+    return;
+
   // Here we try to get rid of Phis which become invariants after 1, 2, ..., N
   // iterations of the loop. For this we compute the number for iterations after
   // which every Phi is guaranteed to become an invariant, and try to peel the
@@ -279,21 +292,12 @@ void llvm::computePeelCount(Loop *L, uns
   if (TripCount)
     return;
 
-  // If the user provided a peel count, use that.
-  bool UserPeelCount = UnrollForcePeelCount.getNumOccurrences() > 0;
-  if (UserPeelCount) {
-    DEBUG(dbgs() << "Force-peeling first " << UnrollForcePeelCount
-                 << " iterations.\n");
-    UP.PeelCount = UnrollForcePeelCount;
-    return;
-  }
-
   // If we don't know the trip count, but have reason to believe the average
   // trip count is low, peeling should be beneficial, since we will usually
   // hit the peeled section.
   // We only do this in the presence of profile information, since otherwise
   // our estimates of the trip count are not reliable enough.
-  if (UP.AllowPeeling && L->getHeader()->getParent()->hasProfileData()) {
+  if (L->getHeader()->getParent()->hasProfileData()) {
     Optional<unsigned> PeelCount = getLoopEstimatedTripCount(L);
     if (!PeelCount)
       return;

Modified: llvm/trunk/test/Transforms/LoopUnroll/peel-loop-not-forced.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopUnroll/peel-loop-not-forced.ll?rev=329395&r1=329394&r2=329395&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/LoopUnroll/peel-loop-not-forced.ll (original)
+++ llvm/trunk/test/Transforms/LoopUnroll/peel-loop-not-forced.ll Fri Apr  6 06:57:21 2018
@@ -1,4 +1,5 @@
 ; RUN: opt < %s -S -loop-unroll -unroll-threshold=30 | FileCheck %s
+; RUN: opt < %s -S -loop-unroll -unroll-threshold=30 -unroll-allow-peeling=false | FileCheck %s --check-prefix=DISABLE
 
 define i32 @invariant_backedge_1(i32 %a, i32 %b) {
 ; CHECK-LABEL: @invariant_backedge_1
@@ -7,6 +8,8 @@ define i32 @invariant_backedge_1(i32 %a,
 ; CHECK:       loop:
 ; CHECK:         %i = phi
 ; CHECK:         %sum = phi
+; DISABLE-LABEL: @invariant_backedge_1
+; DISABLE-NOT: loop.peel:
 entry:
   br label %loop