<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Tue, Mar 29, 2016 at 2:46 PM, Davide Italiano via llvm-commits <span dir="ltr"><<a href="mailto:llvm-commits@lists.llvm.org" target="_blank">llvm-commits@lists.llvm.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Author: davide<br>
Date: Tue Mar 29 16:46:35 2016<br>
New Revision: 264790<br>
<br>
URL: <a href="http://llvm.org/viewvc/llvm-project?rev=264790&view=rev" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-project?rev=264790&view=rev</a><br>
Log:<br>
[LTO] Teach LTO about @llvm.used global.<br>
<br>
If a symbol appears in @llvm.used, the linker is forced to treat<br>
the symbol as there's a reference to it.<br>
<br>
Added:<br>
    lld/trunk/test/ELF/lto/internalize-llvmused.ll<br>
Modified:<br>
    lld/trunk/ELF/LTO.cpp<br>
<br>
Modified: lld/trunk/ELF/LTO.cpp<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/LTO.cpp?rev=264790&r1=264789&r2=264790&view=diff" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/LTO.cpp?rev=264790&r1=264789&r2=264790&view=diff</a><br>
==============================================================================<br>
--- lld/trunk/ELF/LTO.cpp (original)<br>
+++ lld/trunk/ELF/LTO.cpp Tue Mar 29 16:46:35 2016<br>
@@ -21,6 +21,7 @@<br>
 #include "llvm/Support/TargetRegistry.h"<br>
 #include "llvm/Target/TargetMachine.h"<br>
 #include "llvm/Transforms/IPO.h"<br>
+#include "llvm/Transforms/Utils/ModuleUtils.h"<br>
 #include "llvm/Transforms/IPO/PassManagerBuilder.h"<br>
<br>
 using namespace llvm;<br>
@@ -76,6 +77,10 @@ void BitcodeCompiler::add(BitcodeFile &F<br>
   unsigned BodyIndex = 0;<br>
   ArrayRef<SymbolBody *> Bodies = F.getSymbols();<br>
<br>
+  Module &M = Obj->getModule();<br>
+  SmallPtrSet<GlobalValue *, 8> Used;<br>
+  collectUsedGlobalVariables(M, Used, /* CompilerUsed */ false);<br></blockquote><div><br></div><div>Please add a comment.</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
+<br>
   for (const BasicSymbolRef &Sym : Obj->symbols()) {<br>
     GlobalValue *GV = Obj->getSymbolGV(Sym.getRawDataRefImpl());<br>
     assert(GV);<br>
@@ -108,7 +113,8 @@ void BitcodeCompiler::add(BitcodeFile &F<br>
     // For now, let's be conservative and just never internalize<br>
     // symbols when creating a shared library.<br>
     if (!Config->Shared && !Config->ExportDynamic && !B->isUsedInRegularObj())<br>
-      InternalizedSyms.insert(GV->getName());<br>
+      if (!Used.count(GV))<br>
+        InternalizedSyms.insert(GV->getName());<br>
<br>
     Keep.push_back(GV);<br>
   }<br>
<br>
Added: lld/trunk/test/ELF/lto/internalize-llvmused.ll<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/lto/internalize-llvmused.ll?rev=264790&view=auto" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/lto/internalize-llvmused.ll?rev=264790&view=auto</a><br>
==============================================================================<br>
--- lld/trunk/test/ELF/lto/internalize-llvmused.ll (added)<br>
+++ lld/trunk/test/ELF/lto/internalize-llvmused.ll Tue Mar 29 16:46:35 2016<br>
@@ -0,0 +1,20 @@<br>
+; REQUIRES: x86<br>
+; RUN: llvm-as %s -o %t.o<br>
+; RUN: ld.lld -m elf_x86_64 %t.o -o %t2 -save-temps<br>
+; RUN: llvm-dis < %t2.lto.bc | FileCheck %s<br>
+<br>
+target triple = "x86_64-unknown-linux-gnu"<br>
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"<br>
+<br>
+define void @_start() {<br>
+  ret void<br>
+}<br>
+<br>
+define hidden void @f() {<br>
+  ret void<br>
+}<br>
+<br>
+@llvm.used = appending global [1 x i8*] [ i8* bitcast (void ()* @f to i8*)]<br>
+<br>
+; Check that f is not internalized.<br>
+; CHECK: define hidden void @f()<br>
<br>
<br>
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</blockquote></div><br></div></div>