diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Transforms/Scalar/LICM.cpp | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/lib/Transforms/Scalar/LICM.cpp b/lib/Transforms/Scalar/LICM.cpp index 13440c13b6..aef1cd6f6f 100644 --- a/lib/Transforms/Scalar/LICM.cpp +++ b/lib/Transforms/Scalar/LICM.cpp @@ -62,6 +62,15 @@ static cl::opt<bool> 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 VISIBILITY_HIDDEN LICM : public LoopPass { static char ID; // Pass identification, replacement for typeid @@ -372,7 +381,8 @@ bool LICM::canSinkOrHoistInst(Instruction &I) { // 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 (AA->pointsToConstantMemory(LI->getOperand(0))) + if (EnableLICMConstantMotion && + AA->pointsToConstantMemory(LI->getOperand(0))) return true; // Don't hoist loads which have may-aliased stores in loop. |