Attach maximum function count to Module when using PGO mode

This sets the maximum entry count among all functions in the program to the
module using module flags. This allows the optimizer to use this information.

Differential Revision: http://reviews.llvm.org/D15163

llvm-svn: 255397

2 files changed, 12 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 29c5f3eed5a..8d7254904a9 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -376,6 +376,9 @@ void CodeGenModule::Release() {
   }
   if (PGOReader && PGOStats.hasDiagnostics())
     PGOStats.reportDiagnostics(getDiags(), getCodeGenOpts().MainFileName);
+  // In PGO mode, attach maximum function count to the module.
+  if (PGOReader)
+    getModule().setMaximumFunctionCount(PGOReader->getMaximumFunctionCount());
   EmitCtorList(GlobalCtors, "llvm.global_ctors");
   EmitCtorList(GlobalDtors, "llvm.global_dtors");
   EmitGlobalAnnotations();
diff --git a/clang/test/CodeGen/pgo-max-function-count.c b/clang/test/CodeGen/pgo-max-function-count.c
new file mode 100644
index 00000000000..b60a4671eb1
--- /dev/null
+++ b/clang/test/CodeGen/pgo-max-function-count.c
@@ -0,0 +1,9 @@
+// RUN: %clang -fprofile-generate -o %t -O2 %s
+// RUN: env LLVM_PROFILE_FILE=%t.profraw  %t
+// RUN: llvm-profdata merge -o %t.profdata %t.profraw
+// RUN: %clang -fprofile-use=%t.profdata -o - -S -emit-llvm %s | FileCheck %s
+// Check
+int main() {
+  return 0;
+}
+// CHECK: !{{[0-9]+}} = !{i32 1, !"MaxFunctionCount", i32 1}