From: Jessica Paquette <jpaquette@apple.com>
Date: Mon, 25 Jun 2018 17:36:05 +0000 (+0000)
Subject: [MachineOutliner] Outline from linkonceodrs by default in LTO when -moutline is passed
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=7f4f83642fbc23380edd820247831effe53a8cb9;p=clang

[MachineOutliner] Outline from linkonceodrs by default in LTO when -moutline is passed

Pass -enable-linkonceodr-outlining by default when LTO is enabled.

The outliner shouldn't compete with any sort of linker deduplication
on linkonceodr functions when LTO is enabled. Therefore, this behaviour
should be the default.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@335504 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Driver/ToolChains/Clang.cpp b/lib/Driver/ToolChains/Clang.cpp
index 248c460aa0..5cb3796723 100644
--- a/lib/Driver/ToolChains/Clang.cpp
+++ b/lib/Driver/ToolChains/Clang.cpp
@@ -1482,6 +1482,14 @@ void Clang::AddAArch64TargetArgs(const ArgList &Args,
     if (A->getOption().matches(options::OPT_moutline)) {
       CmdArgs.push_back("-mllvm");
       CmdArgs.push_back("-enable-machine-outliner");
+
+      // The outliner shouldn't compete with linkers that dedupe linkonceodr
+      // functions in LTO. Enable that behaviour by default when compiling with
+      // LTO.
+      if (getToolChain().getDriver().isUsingLTO()) {
+        CmdArgs.push_back("-mllvm");
+        CmdArgs.push_back("-enable-linkonceodr-outlining");
+      }
     }
   }
 }
diff --git a/test/Driver/aarch64-outliner.c b/test/Driver/aarch64-outliner.c
index 311ee59901..dd2ae2a66c 100644
--- a/test/Driver/aarch64-outliner.c
+++ b/test/Driver/aarch64-outliner.c
@@ -3,3 +3,7 @@
 // ON: "-mllvm" "-enable-machine-outliner"
 // RUN: %clang -target aarch64 -moutline -mno-outline -S %s -### 2>&1 | FileCheck %s -check-prefix=OFF
 // OFF-NOT: "-mllvm" "-enable-machine-outliner"
+// RUN: %clang -target aarch64 -moutline -flto=thin -S %s -### 2>&1 | FileCheck %s -check-prefix=FLTO
+// FLTO: "-mllvm" "-enable-linkonceodr-outlining"
+// RUN: %clang -target aarch64 -moutline -flto=full -S %s -### 2>&1 | FileCheck %s -check-prefix=TLTO
+// TLTO: "-mllvm" "-enable-linkonceodr-outlining"