From 3c0410d09d54a6ea660e8b350be3cc2543b26635 Mon Sep 17 00:00:00 2001
From: Davide Italiano <davide@freebsd.org>
Date: Thu, 21 Apr 2016 04:46:22 +0000
Subject: [PATCH] [LTO] Discard names for Values that are not global.

This is not on by default (but it might be in the future).
The knob to enable the optimization is -lto-discard-value-names.

llvm-svn: 266953
---
 lld/ELF/Config.h                        |  1 +
 lld/ELF/Driver.cpp                      |  1 +
 lld/ELF/LTO.h                           |  2 ++
 lld/ELF/Options.td                      |  1 +
 lld/test/ELF/lto/discard-value-names.ll | 33 +++++++++++++++++++++++++++++++++
 5 files changed, 38 insertions(+)
 create mode 100644 lld/test/ELF/lto/discard-value-names.ll

diff --git a/lld/ELF/Config.h b/lld/ELF/Config.h
index d197122..b050d9b 100644
--- a/lld/ELF/Config.h
+++ b/lld/ELF/Config.h
@@ -58,6 +58,7 @@ struct Configuration {
   bool Demangle = true;
   bool DisableVerify;
   bool DiscardAll;
+  bool DiscardValueNames;
   bool DiscardLocals;
   bool DiscardNone;
   bool EhFrameHdr;
diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp
index f72fa3d..dc49530 100644
--- a/lld/ELF/Driver.cpp
+++ b/lld/ELF/Driver.cpp
@@ -289,6 +289,7 @@ void LinkerDriver::readConfigs(opt::InputArgList &Args) {
   Config->Demangle = !Args.hasArg(OPT_no_demangle);
   Config->DisableVerify = Args.hasArg(OPT_disable_verify);
   Config->DiscardAll = Args.hasArg(OPT_discard_all);
+  Config->DiscardValueNames = Args.hasArg(OPT_lto_discard_value_names);
   Config->DiscardLocals = Args.hasArg(OPT_discard_locals);
   Config->DiscardNone = Args.hasArg(OPT_discard_none);
   Config->EhFrameHdr = Args.hasArg(OPT_eh_frame_hdr);
diff --git a/lld/ELF/LTO.h b/lld/ELF/LTO.h
index 9d4da5d..1bc67d7 100644
--- a/lld/ELF/LTO.h
+++ b/lld/ELF/LTO.h
@@ -21,6 +21,7 @@
 #ifndef LLD_ELF_LTO_H
 #define LLD_ELF_LTO_H
 
+#include "Config.h"
 #include "lld/Core/LLVM.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringSet.h"
@@ -41,6 +42,7 @@ public:
 
   BitcodeCompiler()
       : Combined(new llvm::Module("ld-temp.o", Context)), Mover(*Combined) {
+    Context.setDiscardValueNames(Config->DiscardValueNames);
     Context.enableDebugTypeODRUniquing();
   }
 
diff --git a/lld/ELF/Options.td b/lld/ELF/Options.td
index 49e9b3f..8205de8 100644
--- a/lld/ELF/Options.td
+++ b/lld/ELF/Options.td
@@ -238,6 +238,7 @@ def G : Separate<["-"], "G">;
 def alias_version_script_version_script : Joined<["--"], "version-script=">, Alias<version_script>;
 
 // LTO-related options.
+def lto_discard_value_names : Flag<["-"], "lto-discard-value-names">;
 def lto_jobs : Joined<["--"], "lto-jobs=">,
   HelpText<"Number of threads to run codegen">;
 def disable_verify : Flag<["-"], "disable-verify">;
diff --git a/lld/test/ELF/lto/discard-value-names.ll b/lld/test/ELF/lto/discard-value-names.ll
new file mode 100644
index 0000000..a767401
--- /dev/null
+++ b/lld/test/ELF/lto/discard-value-names.ll
@@ -0,0 +1,33 @@
+; RUN: llvm-as %s -o %t.o
+
+; RUN: ld.lld -m elf_x86_64 -shared -save-temps %t.o -o %t2.o
+; RUN: llvm-dis < %t2.o.lto.bc | FileCheck %s
+
+; RUN: ld.lld -m elf_x86_64 -lto-discard-value-names -shared -save-temps %t.o -o %t2.o
+; RUN: llvm-dis < %t2.o.lto.bc | FileCheck --check-prefix=NONAME %s
+
+; CHECK: @GlobalValueName
+; CHECK: @foo(i32 %in)
+; CHECK: somelabel:
+; CHECK:  %GV = load i32, i32* @GlobalValueName
+; CHECK:  %add = add i32 %in, %GV
+; CHECK:  ret i32 %add
+
+; NONAME: @GlobalValueName
+; NONAME: @foo(i32)
+; NONAME-NOT: somelabel:
+; NONAME:  %2 = load i32, i32* @GlobalValueName
+; NONAME:  %3 = add i32 %0, %2
+; NONAME:  ret i32 %3
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@GlobalValueName = global i32 0
+
+define i32 @foo(i32 %in) {
+somelabel:
+  %GV = load i32, i32* @GlobalValueName
+  %add = add i32 %in, %GV
+  ret i32 %add
+}
-- 
2.7.4