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Re: [PATCH/RFA] sh-elf: Unnecessary relocations


Alan Modra <amodra@bigpond.net.au> wrote:
> On Wed, Oct 02, 2002 at 11:53:54AM -0700, Stephen Clarke wrote:
> > 00000000 <lab2-0x4>:
> >    0:   d0 01           mov.l   8 <lab2+0x4>,r0
> >    2:   00 09           nop
> > 
> > 00000004 <lab2>:
> >    4:   00 00           .word 0x0000
> 
> sh-linux binutils built on Sep 28 assembles and links your testcase
> OK, so it's not the gas reloc rewrite.  phew!  I believe the problem
> is in tc-sh.c:md_pcrel_from_section where it looks like we have some
> hacks to counteract bfd_install_relocation brain-damage.  Since Kaz
> changed the conditions under which we emit relocs, the test there
> needs changing too.  Also, IMO it would be cleaner to move the hacks
> into md_apply_fix3.

Hmm... Surely it's my bad. I've compared the behaviors of old/new
assemblers with gdb and found that tc-sh.c:md_pcrel_from_section()
of the new assember returns 0 instead of 4 which the old one returns.
I don't know why but fixP->fx_addsy->bsym is "lab2" in the new one
and ".text" in the old one.
Now I'm testing the following patch for tc-sh.c. Fixing md_apply_fix3
seems cleaner, but I'm unsure how to do it.
Anyway, we should catch such problems by the testsuite, I think.
How about the following patch for pcrel2 test?

	kaz
--
2002-10-03  Kaz Kojima  <kkojima@rr.iij4u.or.jp>

	* contig/tc-sh.c (sh_local_pcrel): New.
	(sh_force_relocation): Use sh_local_pcrel.
	* testsuite/gas/sh/pcrel2.d: Check code also.

Index: config/tc-sh.c
===================================================================
RCS file: /cvs/src/src/gas/config/tc-sh.c,v
retrieving revision 1.71
diff -u -3 -p -r1.71 tc-sh.c
--- config/tc-sh.c	28 Sep 2002 00:41:26 -0000	1.71
+++ config/tc-sh.c	3 Oct 2002 00:43:18 -0000
@@ -3211,6 +3211,22 @@ sh_handle_align (frag)
 	     BFD_RELOC_SH_ALIGN);
 }
 
+/* See whether the relocation should be resolved locally.  */
+
+static boolean
+sh_local_pcrel (fix)
+     fixS *fix;
+{
+  return (! sh_relax && 
+	  (fix->fx_r_type == BFD_RELOC_SH_PCDISP8BY2
+	   || fix->fx_r_type == BFD_RELOC_SH_PCDISP12BY2
+	   || fix->fx_r_type == BFD_RELOC_SH_PCRELIMM8BY2
+	   || fix->fx_r_type == BFD_RELOC_SH_PCRELIMM8BY4
+	   || fix->fx_r_type == BFD_RELOC_8_PCREL
+	   || fix->fx_r_type == BFD_RELOC_SH_SWITCH16
+	   || fix->fx_r_type == BFD_RELOC_SH_SWITCH32));
+}
+
 /* See whether we need to force a relocation into the output file.
    This is used to force out switch and PC relative relocations when
    relaxing.  */
@@ -3221,14 +3237,7 @@ sh_force_relocation (fix)
 {
   /* These relocations can't make it into a DSO, so no use forcing
      them for global symbols.  */
-  if (! sh_relax
-      && (fix->fx_r_type == BFD_RELOC_SH_PCDISP8BY2
-	  || fix->fx_r_type == BFD_RELOC_SH_PCDISP12BY2
-	  || fix->fx_r_type == BFD_RELOC_SH_PCRELIMM8BY2
-	  || fix->fx_r_type == BFD_RELOC_SH_PCRELIMM8BY4
-	  || fix->fx_r_type == BFD_RELOC_8_PCREL
-	  || fix->fx_r_type == BFD_RELOC_SH_SWITCH16
-	  || fix->fx_r_type == BFD_RELOC_SH_SWITCH32))
+  if (sh_local_pcrel (fix))
     return 0;
 
   if (fix->fx_r_type == BFD_RELOC_VTABLE_INHERIT
@@ -3684,7 +3693,8 @@ md_pcrel_from_section (fixP, sec)
      fixS *fixP;
      segT sec;
 {
-  if (fixP->fx_addsy != (symbolS *) NULL
+  if (! sh_local_pcrel (fixP)
+      && fixP->fx_addsy != (symbolS *) NULL
       && (! S_IS_DEFINED (fixP->fx_addsy)
 	  || S_IS_EXTERN (fixP->fx_addsy)
 	  || S_IS_WEAK (fixP->fx_addsy)
Index: testsuite/gas/sh/pcrel2.d
===================================================================
RCS file: /cvs/src/src/gas/testsuite/gas/sh/pcrel2.d,v
retrieving revision 1.1
diff -u -3 -p -r1.1 pcrel2.d
--- testsuite/gas/sh/pcrel2.d	28 Sep 2002 00:41:27 -0000	1.1
+++ testsuite/gas/sh/pcrel2.d	3 Oct 2002 00:43:37 -0000
@@ -1,5 +1,23 @@
 #as: -big
-#objdump: -r
+#objdump: -drj.text
 #name: PC-relative loads
 
 .*:     file format .*sh.*
+
+Disassembly of section \.text:
+
+00000000 <code>:
+   0:	8b 01       	bf	6 <foo>
+   2:	d0 02       	mov\.l	c <bar>,r0	! 0x6
+   4:	90 02       	mov\.w	c <bar>,r0	! 0x0
+
+00000006 <foo>:
+   6:	af fe       	bra	6 <foo>
+   8:	00 09       	nop	
+   a:	00 09       	nop	
+
+0000000c <bar>:
+   c:	00 00       	.*[ 	]*.*
+   e:	00 06       	.*[ 	]*.*
+  10:	00 0a       	.*[ 	]*.*
+  12:	0c 00       	.*[ 	]*.*


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