Patchwork [trunk,RFA] Add __i686.get_pc_thunk.bx to libgcc i386 morestack.S

login
register
mail settings
Submitter Chris Demetriou
Date May 4, 2011, 7:52 a.m.
Message ID <BANLkTikOt15c+50_f8x5VakVYRDFHDix9Q@mail.gmail.com>
Download mbox | patch
Permalink /patch/93983/
State New
Headers show

Comments

Chris Demetriou - May 4, 2011, 7:52 a.m.
On Tue, May 3, 2011 at 16:39, Chris Demetriou <cgd@google.com> wrote:
> > It is also OK if you s/__i686/__x86/ to correspond to your earlier
> > change.  Either way is OK.
>
> Well, that change is not in trunk.
> Should that change move to trunk, yes, it's appropriate to change this
> as well (though strictly not *necessary*).

*sigh*

As it turns out, adding __i686.get_pc_thunk.bx to this assembly code
-- *cough* this _preprocessed_ assembly code -- chokes in certain
configurations.

For instance, if you configure with:
  --with-arch-32=pentium3
then libgcc will build with -march=pentium3

The way the symbol-visibility files are built and processed,
morestack.vis is generated from morestack.S, and contains:
        .hidden __i686.get_pc_thunk.bx
morestack.vis is included via -include when compiling morestack.S.

./morestack.vis:4: Error: junk at end of line, first unrecognized
character is `1'

As someone smarter than me might have guessed... in this
configuration, __i686 is defined to be '1'.
So, even if the trunk get_thunk code continues to use
__i686.get_pc_thunk.<reg>, it's necessary to use something different
here.

Kinda feels like I got smacked in the face by walking into my own
rake...  *sigh*


Ian, per your previous comment (which I read as pre-approval for this
change 8-), I'm planning to commit the attached as soon as it's done
testing.


chris
-----
[libgcc/ChangeLog]
2011-05-04  Chris Demetriou  <cgd@google.com>

        * config/i386/morestack.S (__i686.get_pc_thunk.bx): Rename...
        (__x86.get_pc_thunk.bx): To this.
        (__morestack): Adjust for rename, remove undef of __i686.
Chris Demetriou - May 4, 2011, 7 p.m.
On Wed, May 4, 2011 at 00:52, Chris Demetriou <cgd@google.com> wrote:
> Ian, per your previous comment (which I read as pre-approval for this
> change 8-), I'm planning to commit the attached as soon as it's done
> testing.
>
>
> chris
> -----
> [libgcc/ChangeLog]
> 2011-05-04  Chris Demetriou  <cgd@google.com>
>
>        * config/i386/morestack.S (__i686.get_pc_thunk.bx): Rename...
>        (__x86.get_pc_thunk.bx): To this.
>        (__morestack): Adjust for rename, remove undef of __i686.
>

Passed my tests (bootstrap C + test C on ubuntu lucid x86-64, with and
w/o --with-pic), so submitted @ r173391.
Slightly different changelog message:


2011-05-04  Chris Demetriou  <cgd@google.com>

        * config/i386/morestack.S (__i686.get_pc_thunk.bx): Rename to...
        (__x86.get_pc_thunk.bx): ...this.
        (__morestack): Adjust for rename, remove undef of __i686.

(more consistent with other renames in the same file.  8-)


sorry for the churn.


chris

Patch

[libgcc/ChangeLog]
2011-05-04  Chris Demetriou  <cgd@google.com>

	* config/i386/morestack.S (__i686.get_pc_thunk.bx): Rename...
	(__x86.get_pc_thunk.bx): To this.
	(__morestack): Adjust for rename, remove undef of __i686.

Index: libgcc/config/i386/morestack.S
===================================================================
--- libgcc/config/i386/morestack.S	(revision 173355)
+++ libgcc/config/i386/morestack.S	(working copy)
@@ -278,8 +278,7 @@ 
 	movl	4(%esp),%eax		# Function argument.
 	movl	%eax,(%esp)
 #ifdef __PIC__
-#undef __i686
-	call	__i686.get_pc_thunk.bx	# %ebx may not be set up for us.
+	call	__x86.get_pc_thunk.bx	# %ebx may not be set up for us.
 	addl	$_GLOBAL_OFFSET_TABLE_, %ebx
 	call	_Unwind_Resume@PLT	# Resume unwinding.
 #else
@@ -451,20 +450,19 @@ 
 
 #if !defined(__x86_64__) && defined(__PIC__)
 # Output the thunk to get PC into bx, since we use it above.
-# (__i686 was already undef'd above; don't need to worry about it here.)
-	.section	.text.__i686.get_pc_thunk.bx,"axG",@progbits,__i686.get_pc_thunk.bx,comdat
-	.globl	__i686.get_pc_thunk.bx
-	.hidden	__i686.get_pc_thunk.bx
+	.section	.text.__x86.get_pc_thunk.bx,"axG",@progbits,__x86.get_pc_thunk.bx,comdat
+	.globl	__x86.get_pc_thunk.bx
+	.hidden	__x86.get_pc_thunk.bx
 #ifdef __ELF__
-	.type	__i686.get_pc_thunk.bx, @function
+	.type	__x86.get_pc_thunk.bx, @function
 #endif
-__i686.get_pc_thunk.bx:
+__x86.get_pc_thunk.bx:
 	.cfi_startproc
 	movl	(%esp), %ebx
 	ret
 	.cfi_endproc
 #ifdef __ELF__
-	.size	__i686.get_pc_thunk.bx, . - __i686.get_pc_thunk.bx
+	.size	__x86.get_pc_thunk.bx, . - __x86.get_pc_thunk.bx
 #endif
 #endif