Include static prof data when collecting loop BBs

Summary:
If the programmer adds static profile data to a branch---i.e. uses
"__builtin_expect()" or similar---then we should honor it. Otherwise,
"__builtin_expect()" is ignored in crucial situations. So we trust that
the programmer knows what they're doing until proven wrong.

Subscribers: hiraditya, JDevlieghere, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D74809

1 files changed, 7 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/MachineLoopInfo.cpp b/llvm/lib/CodeGen/MachineLoopInfo.cpp
index 0c1439d..67916fb 100644
--- a/llvm/lib/CodeGen/MachineLoopInfo.cpp
+++ b/llvm/lib/CodeGen/MachineLoopInfo.cpp
@@ -111,6 +111,13 @@ DebugLoc MachineLoop::getStartLoc() const {
   return DebugLoc();
 }
 
+bool MachineLoop::hasStaticProfInfo() const {
+  return llvm::any_of(blocks(), [](const MachineBasicBlock *MBB){
+    const BasicBlock *BB = MBB->getBasicBlock();
+    return BB && BB->getTerminator()->hasMetadata(LLVMContext::MD_prof);
+  });
+}
+
 MachineBasicBlock *
 MachineLoopInfo::findLoopPreheader(MachineLoop *L,
                                    bool SpeculativePreheader) const {