[llvm] r288141 - [GVNHoist] Enable aggressive hoisting when optimizing for code-size
Aditya Kumar via llvm-commits
llvm-commits at lists.llvm.org
Tue Nov 29 06:34:02 PST 2016
Author: hiraditya
Date: Tue Nov 29 08:34:01 2016
New Revision: 288141
URL: http://llvm.org/viewvc/llvm-project?rev=288141&view=rev
Log:
[GVNHoist] Enable aggressive hoisting when optimizing for code-size
Enable scalar hoisting at -Oz as it is safe to hoist scalars to a place
where they are partially needed.
Differential Revision: https://reviews.llvm.org/D27111
Modified:
llvm/trunk/lib/Transforms/Scalar/GVNHoist.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/GVNHoist.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/GVNHoist.cpp?rev=288141&r1=288140&r2=288141&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/GVNHoist.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/GVNHoist.cpp Tue Nov 29 08:34:01 2016
@@ -202,7 +202,12 @@ public:
GVNHoist(DominatorTree *DT, AliasAnalysis *AA, MemoryDependenceResults *MD,
MemorySSA *MSSA, bool OptForMinSize)
: DT(DT), AA(AA), MD(MD), MSSA(MSSA), OptForMinSize(OptForMinSize),
- HoistingGeps(OptForMinSize), HoistedCtr(0) {}
+ HoistingGeps(OptForMinSize), HoistedCtr(0) {
+ // Hoist as far as possible when optimizing for code-size.
+ if (OptForMinSize)
+ MaxNumberOfBBSInPath = -1;
+ }
+
bool run(Function &F) {
VN.setDomTree(DT);
VN.setAliasAnalysis(AA);
@@ -500,10 +505,13 @@ private:
bool safeToHoistScalar(const BasicBlock *HoistBB,
SmallPtrSetImpl<const BasicBlock *> &WL,
int &NBBsOnAllPaths) {
- // Check that the hoisted expression is needed on all paths. Enable scalar
- // hoisting at -Oz as it is safe to hoist scalars to a place where they are
- // partially needed.
- if (!OptForMinSize && !hoistingFromAllPaths(HoistBB, WL))
+ // Enable scalar hoisting at -Oz as it is safe to hoist scalars to a place
+ // where they are partially needed.
+ if (OptForMinSize)
+ return true;
+
+ // Check that the hoisted expression is needed on all paths.
+ if (!hoistingFromAllPaths(HoistBB, WL))
return false;
for (const BasicBlock *BB : WL)
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