[PGO] Profile guided code size optimization.

Summary:
Enable some of the existing size optimizations for cold code under PGO.

A ~5% code size saving in big internal app under PGO.

The way it gets BFI/PSI is discussed in the RFC thread

http://lists.llvm.org/pipermail/llvm-dev/2019-March/130894.html 

Note it doesn't currently touch loop passes.

Reviewers: davidxl, eraman

Reviewed By: eraman

Subscribers: mgorny, javed.absar, smeenai, mehdi_amini, eraman, zzheng, steven_wu, dexonsmith, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59514

llvm-svn: 358422

1 files changed, 7 insertions, 3 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
index ee1853613bc..a42cf95b45a 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
+++ b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
@@ -52,12 +52,14 @@ namespace llvm {
 
 class APInt;
 class AssumptionCache;
+class BlockFrequencyInfo;
 class DataLayout;
 class DominatorTree;
 class GEPOperator;
 class GlobalVariable;
 class LoopInfo;
 class OptimizationRemarkEmitter;
+class ProfileSummaryInfo;
 class TargetLibraryInfo;
 class User;
 
@@ -304,6 +306,8 @@ private:
   const DataLayout &DL;
   const SimplifyQuery SQ;
   OptimizationRemarkEmitter &ORE;
+  BlockFrequencyInfo *BFI;
+  ProfileSummaryInfo *PSI;
 
   // Optional analyses. When non-null, these can both be used to do better
   // combining and will be updated to reflect any changes.
@@ -315,11 +319,11 @@ public:
   InstCombiner(InstCombineWorklist &Worklist, BuilderTy &Builder,
                bool MinimizeSize, bool ExpensiveCombines, AliasAnalysis *AA,
                AssumptionCache &AC, TargetLibraryInfo &TLI, DominatorTree &DT,
-               OptimizationRemarkEmitter &ORE, const DataLayout &DL,
-               LoopInfo *LI)
+               OptimizationRemarkEmitter &ORE, BlockFrequencyInfo *BFI,
+               ProfileSummaryInfo *PSI, const DataLayout &DL, LoopInfo *LI)
       : Worklist(Worklist), Builder(Builder), MinimizeSize(MinimizeSize),
         ExpensiveCombines(ExpensiveCombines), AA(AA), AC(AC), TLI(TLI), DT(DT),
-        DL(DL), SQ(DL, &TLI, &DT, &AC), ORE(ORE), LI(LI) {}
+        DL(DL), SQ(DL, &TLI, &DT, &AC), ORE(ORE), BFI(BFI), PSI(PSI), LI(LI) {}
 
   /// Run the combiner over the entire worklist until it is empty.
   ///