[llvm-commits] [llvm] r111042 - /llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp

[Dan Gohman]

Author: djg
Date: Fri Aug 13 16:17:19 2010
New Revision: 111042

URL: http://llvm.org/viewvc/llvm-project?rev=111042&view=rev
Log:
Fix LSR's ExtractImmediate and ExtractSymbol to avoid calling
ScalarEvolution::getAddExpr, which can be pretty expensive, when nothing
has changed, which is pretty common.

Modified:
    llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp?rev=111042&r1=111041&r2=111042&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp Fri Aug 13 16:17:19 2010
@@ -505,12 +505,14 @@
   } else if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
     SmallVector<const SCEV *, 8> NewOps(Add->op_begin(), Add->op_end());
     int64_t Result = ExtractImmediate(NewOps.front(), SE);
-    S = SE.getAddExpr(NewOps);
+    if (Result != 0)
+      S = SE.getAddExpr(NewOps);
     return Result;
   } else if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
     SmallVector<const SCEV *, 8> NewOps(AR->op_begin(), AR->op_end());
     int64_t Result = ExtractImmediate(NewOps.front(), SE);
-    S = SE.getAddRecExpr(NewOps, AR->getLoop());
+    if (Result != 0)
+      S = SE.getAddRecExpr(NewOps, AR->getLoop());
     return Result;
   }
   return 0;
@@ -528,12 +530,14 @@
   } else if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
     SmallVector<const SCEV *, 8> NewOps(Add->op_begin(), Add->op_end());
     GlobalValue *Result = ExtractSymbol(NewOps.back(), SE);
-    S = SE.getAddExpr(NewOps);
+    if (Result)
+      S = SE.getAddExpr(NewOps);
     return Result;
   } else if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
     SmallVector<const SCEV *, 8> NewOps(AR->op_begin(), AR->op_end());
     GlobalValue *Result = ExtractSymbol(NewOps.front(), SE);
-    S = SE.getAddRecExpr(NewOps, AR->getLoop());
+    if (Result)
+      S = SE.getAddRecExpr(NewOps, AR->getLoop());
     return Result;
   }
   return 0;