[PATCH] D18316: [PATCH] Force RerollLoop pass to reset the loop trip count value for rerolled loops

[Zinovy Nis via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rL264051: [PATCH] Force LoopReroll to reset the loop trip count value after reroll. (authored by zinovy.nis).

Changed prior to commit:
  http://reviews.llvm.org/D18316?vs=51163&id=51280#toc

Repository:
  rL LLVM

http://reviews.llvm.org/D18316

Files:
  llvm/trunk/lib/Transforms/Scalar/LoopRerollPass.cpp
  llvm/trunk/test/Transforms/LoopReroll/basic32iters.ll

Index: llvm/trunk/test/Transforms/LoopReroll/basic32iters.ll
===================================================================
--- llvm/trunk/test/Transforms/LoopReroll/basic32iters.ll
+++ llvm/trunk/test/Transforms/LoopReroll/basic32iters.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -loop-reroll -S | FileCheck %s
+; RUN: opt < %s -loop-reroll -verify-scev -S | FileCheck %s
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
Index: llvm/trunk/lib/Transforms/Scalar/LoopRerollPass.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopRerollPass.cpp
+++ llvm/trunk/lib/Transforms/Scalar/LoopRerollPass.cpp
@@ -1551,14 +1551,12 @@
         "] Loop %" << Header->getName() << " (" <<
         L->getNumBlocks() << " block(s))\n");
 
-  bool Changed = false;
-
   // For now, we'll handle only single BB loops.
   if (L->getNumBlocks() > 1)
-    return Changed;
+    return false;
 
   if (!SE->hasLoopInvariantBackedgeTakenCount(L))
-    return Changed;
+    return false;
 
   const SCEV *LIBETC = SE->getBackedgeTakenCount(L);
   const SCEV *IterCount = SE->getAddExpr(LIBETC, SE->getOne(LIBETC->getType()));
@@ -1572,11 +1570,12 @@
 
   if (PossibleIVs.empty()) {
     DEBUG(dbgs() << "LRR: No possible IVs found\n");
-    return Changed;
+    return false;
   }
 
   ReductionTracker Reductions;
   collectPossibleReductions(L, Reductions);
+  bool Changed = false;
 
   // For each possible IV, collect the associated possible set of 'root' nodes
   // (i+1, i+2, etc.).
@@ -1587,5 +1586,9 @@
       break;
     }
 
+  // Trip count of L has changed so SE must be re-evaluated.
+  if (Changed)
+    SE->forgetLoop(L);
+
   return Changed;
 }


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