[PATCH] microblaze: add BFD_RELOC_8 and BFD_RELOC_16 cases

[Sam Price]

From: Samuel Price <thesamprice@gmail.com>

md_apply_fix has cases for BFD_RELOC_32, BFD_RELOC_64 and for the
MicroBlaze-specific relocations, but none for BFD_RELOC_8 or BFD_RELOC_16.
Those fall through to the default and nothing is written, so a byte or
halfword datum whose value is only known at fixup time assembles to zero.
The fixup is then resolved and turned into BFD_RELOC_NONE, so no relocation
survives for the linker to correct it either, and the zero is permanent.

The two new cases replicate the BFD_RELOC_32 case immediately below them in
the same switch -- the same S_IS_DEFINED guard and the same target_big_endian
byte order -- narrowed to one and two bytes.

Fixes gas/all/simple-forward.  It also fixes gas/all/forward, which was
xfailed for microblaze-*-*, so drop it from that xfail list.  The gas
testsuite on microblaze-elf goes from 327 passes and 1 unexpected failure to
329 passes and 0 failures.

gas/
	* config/tc-microblaze.c (md_apply_fix): Handle BFD_RELOC_8 and
	BFD_RELOC_16.
	* testsuite/gas/all/forward.d: Remove the microblaze-*-* xfail.

Signed-off-by: Sam Price <thesamprice@gmail.com>
Assisted-by: Claude (Anthropic)
---

I considered writing the two new cases the way aarch64 and mips do instead --

  case BFD_RELOC_16:
  case BFD_RELOC_8:
    if (fixP->fx_done)
      md_number_to_chars (buf, *valP, fixP->fx_size);
    break;

-- which is shorter, drops the endianness branch, and guards on fx_done
rather than S_IS_DEFINED, which is arguably what is really meant here.  The
comment on that case in tc-mips.c describes this exact failure mode: "If we
are deleting this reloc entry, we must fill in the value now."

I kept the local form so the patch stays minimal and consistent with its
neighbour, but I am happy to send the md_number_to_chars version instead if
you would rather have it.  Or if you want the neighbors converted to
aarch64 / mips and tested I can do that also.

 gas/config/tc-microblaze.c      | 23 +++++++++++++++++++++++
 gas/testsuite/gas/all/forward.d |  2 +-
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/gas/config/tc-microblaze.c b/gas/config/tc-microblaze.c
index 3e3dca81921..36b98bbd8fc 100644
--- a/gas/config/tc-microblaze.c
+++ b/gas/config/tc-microblaze.c
@@ -2145,6 +2145,29 @@ md_apply_fix (fixS *   fixP,
 	    }
 	}
       break;
+    case BFD_RELOC_8:
+      /* Don't do anything if the symbol is not defined.  */
+      if (fixP->fx_addsy == NULL || S_IS_DEFINED (fixP->fx_addsy))
+	buf[0] |= (val & 0xff);
+      break;
+
+    case BFD_RELOC_16:
+      /* Don't do anything if the symbol is not defined.  */
+      if (fixP->fx_addsy == NULL || S_IS_DEFINED (fixP->fx_addsy))
+	{
+	  if (target_big_endian)
+	    {
+	      buf[0] |= ((val >> 8) & 0xff);
+	      buf[1] |= (val & 0xff);
+	    }
+	  else
+	    {
+	      buf[1] |= ((val >> 8) & 0xff);
+	      buf[0] |= (val & 0xff);
+	    }
+	}
+      break;
+
     case BFD_RELOC_32:
     case BFD_RELOC_RVA:
     case BFD_RELOC_32_PCREL:
diff --git a/gas/testsuite/gas/all/forward.d b/gas/testsuite/gas/all/forward.d
index d921ec517be..360ab778ebb 100644
--- a/gas/testsuite/gas/all/forward.d
+++ b/gas/testsuite/gas/all/forward.d
@@ -11,7 +11,7 @@
 # mep and microblaze use complex relocs and don't resolve the relocs.
 # one of the relocs references minus_one, which is a bug, but no one
 # seems bothered enough to fix this.
-#xfail: mep-*-* microblaze-*-*
+#xfail: mep-*-*
 
 .*: .*
 
-- 
2.39.5 (Apple Git-154)