llvm dev - Jun 2013 - [LLVMdev] [PATCH] gcc-4.8.1 -flto, error for visibility of LLVMX86CompilationCallback2?

Thanks, now it links.

If nobody objects, I will commit the following patch:

diff --git a/lib/Target/X86/X86JITInfo.cpp b/lib/Target/X86/X86JITInfo.cpp
index 44d8cce..8acc220 100644
--- a/lib/Target/X86/X86JITInfo.cpp
+++ b/lib/Target/X86/X86JITInfo.cpp
@@ -339,6 +339,8 @@ extern "C" {
 /// must locate the start of the stub or call site and pass it into the JIT
 /// compiler function.
 extern "C" {
+LLVM_ATTRIBUTE_USED // Fix gcc -flto builds. gcc's LTO (as of 4.8.1)
don't sees
+                    // references from inline asm.
 LLVM_LIBRARY_VISIBILITY void LLVMX86CompilationCallback2(intptr_t *StackPtr,
                                                          intptr_t RetAddr) {
   intptr_t *RetAddrLoc = &StackPtr[1];

(However, I still can't link unittest programs, because of the use of anchor
methods in CommandLine. I will take a look at it shortly.)

/Patrik Hägglund

-----Original Message-----
From: Rafael Espíndola [mailto:rafael.espindola at gmail.com] 
Sent: den 10 juni 2013 15:20
To: Patrik Hägglund H
Cc: llvmdev at cs.uiuc.edu
Subject: Re: gcc-4.8.1 -flto, error for visibility of
LLVMX86CompilationCallback2?

On 10 June 2013 08:45, Patrik Hägglund H <patrik.h.hagglund at
ericsson.com> wrote:
> I tried to compile LLVM with gcc-4.8.1 -flto. I got the following error,
when linking lli, llc, opt, or libLTO.so:
>
> `LLVMX86CompilationCallback2' referenced in section `.text' of
/tmp/cclv7BYB.ltrans0.ltrans.o: defined in discarded section `.text' of
X86JITInfo.o (symbol from plugin)
> collect2: error: ld returned 1 exit status
>
> Removing the LLVM_LIBRARY_VISIBILITY attribute for
LLVMX86CompilationCallback2 make the link pass for lli, llc, and opt, but not
for libLTO.so.
>
> Any ideas why this happens?
I don't think gcc's LTO sees references from inline asm. Does adding
__attribute__((used)) work?
> /Patrik Hägglund
Cheers,
Rafael

Hi Patrik,

On 12/06/13 09:48, Patrik Hägglund H wrote:
> Thanks, now it links.
>
> If nobody objects, I will commit the following patch:
>
> diff --git a/lib/Target/X86/X86JITInfo.cpp b/lib/Target/X86/X86JITInfo.cpp
> index 44d8cce..8acc220 100644
> --- a/lib/Target/X86/X86JITInfo.cpp
> +++ b/lib/Target/X86/X86JITInfo.cpp
> @@ -339,6 +339,8 @@ extern "C" {
>   /// must locate the start of the stub or call site and pass it into the
JIT
>   /// compiler function.
>   extern "C" {
> +LLVM_ATTRIBUTE_USED // Fix gcc -flto builds. gcc's LTO (as of 4.8.1)
don't sees
> +                    // references from inline asm.
clang also doesn't see references from inline asm...  I suggest you say:

   LLVM_ATTRIBUTE_USED // referenced from inline asm.

Ciao, Duncan.

Thanks. Commited as r183824.

/Patrik Hägglund

-----Original Message-----
From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On
Behalf Of Duncan Sands
Sent: den 12 juni 2013 10:03
To: llvmdev at cs.uiuc.edu
Subject: Re: [LLVMdev] [PATCH] gcc-4.8.1 -flto, error for visibility of
LLVMX86CompilationCallback2?

Hi Patrik,

On 12/06/13 09:48, Patrik Hägglund H wrote:
> Thanks, now it links.
>
> If nobody objects, I will commit the following patch:
>
> diff --git a/lib/Target/X86/X86JITInfo.cpp b/lib/Target/X86/X86JITInfo.cpp
> index 44d8cce..8acc220 100644
> --- a/lib/Target/X86/X86JITInfo.cpp
> +++ b/lib/Target/X86/X86JITInfo.cpp
> @@ -339,6 +339,8 @@ extern "C" {
>   /// must locate the start of the stub or call site and pass it into the
JIT
>   /// compiler function.
>   extern "C" {
> +LLVM_ATTRIBUTE_USED // Fix gcc -flto builds. gcc's LTO (as of 4.8.1)
don't sees
> +                    // references from inline asm.
clang also doesn't see references from inline asm...  I suggest you say:

   LLVM_ATTRIBUTE_USED // referenced from inline asm.

Ciao, Duncan.
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