[PGO] Promote indirect calls to conditional direct calls with value-profile

This patch implements the transformation that promotes indirect calls to
conditional direct calls when the indirect-call value profile meta-data is
available.

Differential Revision: http://reviews.llvm.org/D17864

llvm-svn: 267815

1 files changed, 10 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp b/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
index 16ce04b0e80..b4af849baf3 100644
--- a/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
+++ b/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
@@ -371,10 +371,13 @@ void PassManagerBuilder::populateModulePassManager(
     MPM.add(createCFGSimplificationPass()); // Clean up after IPCP & DAE
   }
 
-  if (!PerformThinLTO)
+  if (!PerformThinLTO) {
     /// PGO instrumentation is added during the compile phase for ThinLTO, do
     /// not run it a second time
     addPGOInstrPasses(MPM);
+    // Indirect call promotion that promotes intra-module targets only.
+    MPM.add(createPGOIndirectCallPromotionPass());
+  }
 
   if (EnableNonLTOGlobalsModRef)
     // We add a module alias analysis pass here. In part due to bugs in the
@@ -585,6 +588,12 @@ void PassManagerBuilder::addLTOOptimizationPasses(legacy::PassManagerBase &PM) {
   // Infer attributes about declarations if possible.
   PM.add(createInferFunctionAttrsLegacyPass());
 
+  // Indirect call promotion. This should promote all the targets that are left
+  // by the earlier promotion pass that promotes intra-module targets.
+  // This two-step promotion is to save the compile time. For LTO, it should
+  // produce the same result as if we only do promotion here.
+  PM.add(createPGOIndirectCallPromotionPass(true));
+
   // Propagate constants at call sites into the functions they call.  This
   // opens opportunities for globalopt (and inlining) by substituting function
   // pointers passed as arguments to direct uses of functions.