Explicitly promote indirect calls before sample profile annotation.

Summary: In iterative sample pgo where profile is collected from PGOed binary, we may see indirect call targets promoted and inlined in the profile. Before profile annotation, we need to make this happen in order to annotate correctly on IR. This patch explicitly promotes these indirect calls and inlines them before profile annotation.

Reviewers: xur, davidxl

Reviewed By: davidxl

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D29040

llvm-svn: 292979

1 files changed, 19 insertions, 5 deletions

diff --git a/llvm/lib/Transforms/IPO/SampleProfile.cpp b/llvm/lib/Transforms/IPO/SampleProfile.cpp
index cba0a813c44..109dbe068ef 100644
--- a/llvm/lib/Transforms/IPO/SampleProfile.cpp
+++ b/llvm/lib/Transforms/IPO/SampleProfile.cpp
@@ -52,6 +52,7 @@
 #include "llvm/Support/Format.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Transforms/IPO.h"
+#include "llvm/Transforms/Instrumentation.h"
 #include "llvm/Transforms/Utils/Cloning.h"
 #include <cctype>
 
@@ -614,14 +615,14 @@ SampleProfileLoader::findFunctionSamples(const Instruction &Inst) const {
 /// Iteratively traverse all callsites of the function \p F, and find if
 /// the corresponding inlined instance exists and is hot in profile. If
 /// it is hot enough, inline the callsites and adds new callsites of the
-/// callee into the caller.
-///
-/// TODO: investigate the possibility of not invoking InlineFunction directly.
+/// callee into the caller. If the call is an indirect call, first promote
+/// it to direct call. Each indirect call is limited with a single target.
 ///
 /// \param F function to perform iterative inlining.
 ///
 /// \returns True if there is any inline happened.
 bool SampleProfileLoader::inlineHotFunctions(Function &F) {
+  DenseSet<Instruction *> PromotedInsns;
   bool Changed = false;
   LLVMContext &Ctx = F.getContext();
   std::function<AssumptionCache &(Function &)> GetAssumptionCache = [&](
@@ -647,10 +648,23 @@ bool SampleProfileLoader::inlineHotFunctions(Function &F) {
     }
     for (auto I : CIS) {
       InlineFunctionInfo IFI(nullptr, ACT ? &GetAssumptionCache : nullptr);
-      CallSite CS(I);
-      Function *CalledFunction = CS.getCalledFunction();
+      Function *CalledFunction = CallSite(I).getCalledFunction();
+      Instruction *DI = I;
+      if (!CalledFunction && !PromotedInsns.count(I)) {
+        CalledFunction = F.getParent()->getFunction(
+            findCalleeFunctionSamples(*I)->getName());
+        if (CalledFunction) {
+          // The indirect target was promoted and inlined in the profile, as a
+          // result, we do not have profile info for the branch probability.
+          // We set the probability to 80% taken to indicate that the static
+          // call is likely taken.
+          DI = promoteIndirectCall(I, CalledFunction, 80, 100);
+          PromotedInsns.insert(I);
+        }
+      }
       if (!CalledFunction || !CalledFunction->getSubprogram())
         continue;
+      CallSite CS(DI);
       DebugLoc DLoc = I->getDebugLoc();
       uint64_t NumSamples = findCalleeFunctionSamples(*I)->getTotalSamples();
       if (InlineFunction(CS, IFI)) {