From 878c8c712fdf2758fcfa1c30cbebdf006fda5568 Mon Sep 17 00:00:00 2001
From: Martin Kinkelin <mkinkelin@symmetryinvestments.com>
Date: Fri, 12 Nov 2021 22:54:12 +0100
Subject: [PATCH] [LDC] PGO: Avoid COMDAT members with private linkage for
 Windows

To prevent according IR verifier errors with IR-based PGO ('comdat
global value has private linkage').
---
 llvm/lib/ProfileData/InstrProf.cpp | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/llvm/lib/ProfileData/InstrProf.cpp b/llvm/lib/ProfileData/InstrProf.cpp
index aee104310a1dd7..5ea6a54d7c7d25 100644
--- a/llvm/lib/ProfileData/InstrProf.cpp
+++ b/llvm/lib/ProfileData/InstrProf.cpp
@@ -360,8 +360,13 @@ GlobalVariable *createPGOFuncNameVar(Module &M,
   else if (Linkage == GlobalValue::AvailableExternallyLinkage)
     Linkage = GlobalValue::LinkOnceODRLinkage;
   else if (Linkage == GlobalValue::InternalLinkage ||
-           Linkage == GlobalValue::ExternalLinkage)
-    Linkage = GlobalValue::PrivateLinkage;
+           Linkage == GlobalValue::ExternalLinkage) {
+    // LDC: use internal instead of private linkage for COFF (still local, but
+    //      allows for COMDATs on Windows)
+    Linkage = Triple(M.getTargetTriple()).isOSBinFormatCOFF()
+                  ? GlobalValue::InternalLinkage
+                  : GlobalValue::PrivateLinkage;
+  }
 
   auto *Value =
       ConstantDataArray::getString(M.getContext(), PGOFuncName, false);