[llvm-commits] [llvm] r89374 - in /llvm/trunk: lib/Transforms/Scalar/LICM.cpp test/Transforms/LICM/2008-07-22-LoadGlobalConstant.ll
Dan Gohman
gohman at apple.com
Thu Nov 19 11:00:10 PST 2009
Author: djg
Date: Thu Nov 19 13:00:10 2009
New Revision: 89374
URL: http://llvm.org/viewvc/llvm-project?rev=89374&view=rev
Log:
Enable hoisting of loads from constant memory by default. In cases where
they are lowered to instruction sequences more complex than a simple
load, such that CodeGen cannot rematerialize them, a reload from a
spill slot is likely to be cheaper than the complex sequence.
Modified:
llvm/trunk/lib/Transforms/Scalar/LICM.cpp
llvm/trunk/test/Transforms/LICM/2008-07-22-LoadGlobalConstant.ll
Modified: llvm/trunk/lib/Transforms/Scalar/LICM.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LICM.cpp?rev=89374&r1=89373&r2=89374&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LICM.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LICM.cpp Thu Nov 19 13:00:10 2009
@@ -63,15 +63,6 @@
DisablePromotion("disable-licm-promotion", cl::Hidden,
cl::desc("Disable memory promotion in LICM pass"));
-// This feature is currently disabled by default because CodeGen is not yet
-// capable of rematerializing these constants in PIC mode, so it can lead to
-// degraded performance. Compile test/CodeGen/X86/remat-constant.ll with
-// -relocation-model=pic to see an example of this.
-static cl::opt<bool>
-EnableLICMConstantMotion("enable-licm-constant-variables", cl::Hidden,
- cl::desc("Enable hoisting/sinking of constant "
- "global variables"));
-
namespace {
struct LICM : public LoopPass {
static char ID; // Pass identification, replacement for typeid
@@ -383,8 +374,7 @@
// Loads from constant memory are always safe to move, even if they end up
// in the same alias set as something that ends up being modified.
- if (EnableLICMConstantMotion &&
- AA->pointsToConstantMemory(LI->getOperand(0)))
+ if (AA->pointsToConstantMemory(LI->getOperand(0)))
return true;
// Don't hoist loads which have may-aliased stores in loop.
Modified: llvm/trunk/test/Transforms/LICM/2008-07-22-LoadGlobalConstant.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LICM/2008-07-22-LoadGlobalConstant.ll?rev=89374&r1=89373&r2=89374&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/LICM/2008-07-22-LoadGlobalConstant.ll (original)
+++ llvm/trunk/test/Transforms/LICM/2008-07-22-LoadGlobalConstant.ll Thu Nov 19 13:00:10 2009
@@ -1,4 +1,4 @@
-; RUN: opt < %s -licm -enable-licm-constant-variables -S | FileCheck %s
+; RUN: opt < %s -licm -S | FileCheck %s
@a = external constant float*
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