Re: [PATCH] Fixed compilation on mingw-w64 after recent ABI change.

[Jacek Caban <jacek@codeweavers.com>]

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On 11/13/10 8:11 AM, Anthony Green wrote:
> Jacek Caban<jacek@codeweavers.com>  writes:
>
>> On 11/4/10 3:22 PM, Jacek Caban wrote:
>>> Hi,
>>>
>>> mingw-w64 ABI has been recently changed to use nonunderscored symbol
>>> names (for compatibility with MSVC). The attached patch fixes libffi
>>> compilation with recent mingw-w64. For backward compatibility, I've
>>> added a configure check for underscored symbols.
>> I've got no response in almost a week, is there something wrong with
>> this patch?
> libffi is a volunteer project for me, which means that contributors
> often have to be patient.

I understand, I just wasn't sure if I should wait or did something wrong.

> The patch looks OK to me.  There's one spelling error ("sumbols").
> FWIW, I prefer libtool's autoconf macro for underscore prefix tests.  It
> compiles code and looks at the nm output to see if symbols are prefixed
> or not.  Your test uses x86 assembly code, although I realize that your
> #ifdef around the config test so that it will only be run on x86 hw.

I wasn't aware of the autoconf macro, it definitely make things look better.

> Please resubmit with the spelling fix and a proper ChangeLog file entry
> and I'll merge it in.  If you switch to the portable '_' test, I'd be
> even happier, but it's not necessary.

Fixed patch is attached.


Thanks for the review,

Jacek

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commit a413fb475b6b64371a916c670b79404cc47813e6
Author: Jacek Caban <jacek@codeweavers.com>
Date:   Thu Nov 4 15:00:56 2010 +0000

    Fixed compilation on mingw-w64 after recent ABI change.

diff --git a/ChangeLog b/ChangeLog
index 5768c10..6232f46 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2010-11-13  Jacek Caban <jacek@codeweavers.com>
+	* configure.ac: Check for symbol underscores on mingw-w64.
+	* src/x86/win64.S: Correctly access extern symbols in respect to
+	underscores.
+
 2010-08-05  Dan Witte  <dwitte@mozilla.com>
 
         * Makefile.am: Pass FFI_DEBUG define to msvcc.sh for linking to the
diff --git a/configure.ac b/configure.ac
index 50f24bc..ac11a9a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -315,6 +315,13 @@ if test x$TARGET = xX86 || test x$TARGET = xX86_WIN32 || test x$TARGET = xX86_64
     fi
 fi
 
+if test x$TARGET = xX86_WIN64; then
+    LT_SYS_SYMBOL_USCORE
+    if test "x$sys_symbol_underscore" = xyes; then
+        AC_DEFINE(SYMBOL_UNDERSCORE, 1, [Define if symbols are underscored.])
+    fi
+fi
+
 case "$target" in
      *-apple-darwin10* | *-*-freebsd* | *-*-openbsd* | *-pc-solaris*)
        AC_DEFINE(FFI_MMAP_EXEC_WRIT, 1,
diff --git a/src/x86/win64.S b/src/x86/win64.S
index 6e91818..fcdb270 100644
--- a/src/x86/win64.S
+++ b/src/x86/win64.S
@@ -232,10 +232,18 @@ ret_void$:
 ffi_call_win64 ENDP
 _TEXT	ENDS
 END
-#else        
+
+#else
+
+#ifdef SYMBOL_UNDERSCORE
+#define SYMBOL_NAME(name) _##name
+#else
+#define SYMBOL_NAME(name) name
+#endif
+
 .text
 
-.extern _ffi_closure_win64_inner
+.extern SYMBOL_NAME(ffi_closure_win64_inner)
 
 # ffi_closure_win64 will be called with these registers set:
 #    rax points to 'closure'
@@ -246,8 +254,8 @@ END
 # call ffi_closure_win64_inner for the actual work, then return the result.
 # 
 	.balign 16
-        .globl _ffi_closure_win64	
-_ffi_closure_win64:     
+        .globl SYMBOL_NAME(ffi_closure_win64)
+SYMBOL_NAME(ffi_closure_win64):
 	# copy register arguments onto stack
 	test	$1,%r11
 	jne	.Lfirst_is_float	
@@ -287,7 +295,7 @@ _ffi_closure_win64:
 	mov	%rax, %rcx	# context is first parameter
 	mov	%rsp, %rdx	# stack is second parameter
 	add	$48, %rdx	# point to start of arguments
-	mov	$_ffi_closure_win64_inner, %rax
+	mov	$SYMBOL_NAME(ffi_closure_win64_inner), %rax
 	callq	*%rax		# call the real closure function
 	add	$40, %rsp
 	movq	%rax, %xmm0	# If the closure returned a float,
@@ -296,8 +304,8 @@ _ffi_closure_win64:
 .ffi_closure_win64_end:
 
 	.balign 16
-        .globl	_ffi_call_win64
-_ffi_call_win64:        
+        .globl	SYMBOL_NAME(ffi_call_win64)
+SYMBOL_NAME(ffi_call_win64):
         # copy registers onto stack
 	mov	%r9,32(%rsp)
 	mov	%r8,24(%rsp)