[llvm] r328875 - Revert "peel loops with runtime small trip counts"

[Krzysztof Parzyszek via llvm-commits]

Author: kparzysz
Date: Fri Mar 30 09:55:44 2018
New Revision: 328875

URL: http://llvm.org/viewvc/llvm-project?rev=328875&view=rev
Log:
Revert "peel loops with runtime small trip counts"

This reverts commit r328854, it breaks some Hexagon tests.

Removed:
    llvm/trunk/test/Transforms/LoopUnroll/Hexagon/peel-small-loop.ll
Modified:
    llvm/trunk/lib/Target/Hexagon/HexagonTargetTransformInfo.cpp
    llvm/trunk/lib/Transforms/Utils/LoopUnrollPeel.cpp

Modified: llvm/trunk/lib/Target/Hexagon/HexagonTargetTransformInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/Hexagon/HexagonTargetTransformInfo.cpp?rev=328875&r1=328874&r2=328875&view=diff
==============================================================================
--- llvm/trunk/lib/Target/Hexagon/HexagonTargetTransformInfo.cpp (original)
+++ llvm/trunk/lib/Target/Hexagon/HexagonTargetTransformInfo.cpp Fri Mar 30 09:55:44 2018
@@ -44,14 +44,6 @@ HexagonTTIImpl::getPopcntSupport(unsigne
 void HexagonTTIImpl::getUnrollingPreferences(Loop *L, ScalarEvolution &SE,
                                              TTI::UnrollingPreferences &UP) {
   UP.Runtime = UP.Partial = true;
-  // Only try to peel innermost loops with small runtime trip counts.
-  if (L && L->empty() &&
-      SE.getSmallConstantTripCount(L) == 0 &&
-      SE.getSmallConstantMaxTripCount(L) > 0 &&
-      SE.getSmallConstantMaxTripCount(L) <= 5) {
-    UP.PeelCount = 2;
-    UP.AllowPeeling = true;
-  }
 }
 
 bool HexagonTTIImpl::shouldFavorPostInc() const {

Modified: llvm/trunk/lib/Transforms/Utils/LoopUnrollPeel.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/LoopUnrollPeel.cpp?rev=328875&r1=328874&r2=328875&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/LoopUnrollPeel.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/LoopUnrollPeel.cpp Fri Mar 30 09:55:44 2018
@@ -221,9 +221,6 @@ void llvm::computePeelCount(Loop *L, uns
                             TargetTransformInfo::UnrollingPreferences &UP,
                             unsigned &TripCount, ScalarEvolution &SE) {
   assert(LoopSize > 0 && "Zero loop size is not allowed!");
-  // Save the UP.PeelCount value set by the target in
-  // TTI.getUnrollingPreferences or by the flag -unroll-peel-count.
-  unsigned TargetPeelCount = UP.PeelCount;
   UP.PeelCount = 0;
   if (!canPeel(L))
     return;
@@ -243,9 +240,7 @@ void llvm::computePeelCount(Loop *L, uns
     SmallDenseMap<PHINode *, unsigned> IterationsToInvariance;
     // Now go through all Phis to calculate their the number of iterations they
     // need to become invariants.
-    // Start the max computation with the UP.PeelCount value set by the target
-    // in TTI.getUnrollingPreferences or by the flag -unroll-peel-count.
-    unsigned DesiredPeelCount = TargetPeelCount;
+    unsigned DesiredPeelCount = 0;
     BasicBlock *BackEdge = L->getLoopLatch();
     assert(BackEdge && "Loop is not in simplified form?");
     for (auto BI = L->getHeader()->begin(); isa<PHINode>(&*BI); ++BI) {

Removed: llvm/trunk/test/Transforms/LoopUnroll/Hexagon/peel-small-loop.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopUnroll/Hexagon/peel-small-loop.ll?rev=328874&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/LoopUnroll/Hexagon/peel-small-loop.ll (original)
+++ llvm/trunk/test/Transforms/LoopUnroll/Hexagon/peel-small-loop.ll (removed)
@@ -1,37 +0,0 @@
-; RUN: opt -loop-unroll -mtriple=hexagon -S < %s | FileCheck %s
-; Check that the loop is peeled twice for Hexagon.
-; CHECK: while.body.peel
-; CHECK: while.body.peel2
-
-%struct.STREAM = type { %union.anon, i32, i32 }
-%union.anon = type { i32* }
-
-define void @function(%struct.STREAM* nocapture readonly %b) local_unnamed_addr {
-entry:
-  %bitPtr3 = getelementptr inbounds %struct.STREAM, %struct.STREAM* %b, i32 0, i32 2
-  %0 = load i32, i32* %bitPtr3, align 4
-  %cmp11 = icmp ult i32 %0, 32
-  br i1 %cmp11, label %while.body.preheader, label %do.end
-
-while.body.preheader:
-  %value2 = getelementptr inbounds %struct.STREAM, %struct.STREAM* %b, i32 0, i32 1
-  %1 = load i32, i32* %value2, align 4
-  %w = getelementptr inbounds %struct.STREAM, %struct.STREAM* %b, i32 0, i32 0, i32 0
-  %2 = load i32*, i32** %w, align 4
-  br label %while.body
-
-while.body:
-  %bitPtr.014 = phi i32 [ %add, %while.body ], [ %0, %while.body.preheader ]
-  %value.013 = phi i32 [ %shl, %while.body ], [ %1, %while.body.preheader ]
-  %ptr.012 = phi i32* [ %incdec.ptr, %while.body ], [ %2, %while.body.preheader ]
-  %add = add nuw i32 %bitPtr.014, 8
-  %shr = lshr i32 %value.013, 24
-  %incdec.ptr = getelementptr inbounds i32, i32* %ptr.012, i32 1
-  store i32 %shr, i32* %ptr.012, align 4
-  %shl = shl i32 %value.013, 8
-  %cmp = icmp ult i32 %add, 17
-  br i1 %cmp, label %while.body, label %do.end
-
-do.end:
-  ret void
-}