gas: Fix mmix fixups and TC_FX_SIZE_SLACK, PR25331

Finally; sorry for the delay.  There were a few false starts, where I
misinterpreted the error-messages and the comment that Alan added:
it's not the fix size that's too large (and the frag too small), it's
stating the wrong size of what will be "fixed up" - that of the actual
target value, not the size of the field that needs to be adjusted.
Comments added for clarity.

Test-suite committed separately.

gas:
	PR gas/25331
	* config/tc-mmix.c (md_assemble) <fixup for
	BFD_RELOC_MMIX_BASE_PLUS_OFFSET>: This fixup affects 1 byte, not 8.
	Also, set its fx_no_overflow.
	(md_convert_frag) <case ENCODE_RELAX (STATE_PUSHJSTUB, STATE_ZERO)>:
	Similarly this fixup affects 4 bytes, not 8 and needs its
	fx_no_overflow set.
	* config/tc-mmix.h (TC_FX_SIZE_SLACK): Don't define.

diff --git a/gas/ChangeLog b/gas/ChangeLog
index a498748a9a4cd98c57bd012a159019d57193f1b4..16e133a8e6fa1da8f49410dd0e4aeb7a7a6ffb96 100644 (file)
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,14 @@
+2020-06-29  Hans-Peter Nilsson  <hp@bitrange.com>
+
+       PR gas/25331
+       * config/tc-mmix.c (md_assemble) <fixup for
+       BFD_RELOC_MMIX_BASE_PLUS_OFFSET>: This fixup affects 1 byte, not 8.
+       Also, set its fx_no_overflow.
+       (md_convert_frag) <case ENCODE_RELAX (STATE_PUSHJSTUB, STATE_ZERO)>: 
+       Similarly this fixup affects 4 bytes, not 8 and needs its
+       fx_no_overflow set.
+       * config/tc-mmix.h (TC_FX_SIZE_SLACK): Don't define.
+
 2020-06-29  Alan Modra  <amodra@gmail.com>
 
        * config/tc-s12z.c: Use C style comments.

diff --git a/gas/config/tc-mmix.c b/gas/config/tc-mmix.c
index a7728fa7937b4e39690f584a989ce483ae1b240c..f97953fe2a9beb919e862c42cd747969c8abc7ad 100644 (file)
--- a/gas/config/tc-mmix.c
+++ b/gas/config/tc-mmix.c
@@ -1332,6 +1332,7 @@ md_assemble (char *str)
       if (n_operands == 2)
        {
          symbolS *sym;
+         fixS *tmpfixP;
 
          /* The last operand is immediate whenever we see just two
             operands.  */
@@ -1380,8 +1381,13 @@ md_assemble (char *str)
          /* Now we know it can be a "base address plus offset".  Add
             proper fixup types so we can handle this later, when we've
             parsed everything.  */
-         fix_new (opc_fragP, opcodep - opc_fragP->fr_literal + 2,
-                  8, sym, 0, 0, BFD_RELOC_MMIX_BASE_PLUS_OFFSET);
+         tmpfixP
+           = fix_new (opc_fragP, opcodep - opc_fragP->fr_literal + 2,
+                      1, sym, 0, 0, BFD_RELOC_MMIX_BASE_PLUS_OFFSET);
+         /* This is a non-trivial fixup: the ->fx_offset will not
+            reflect the stored value, so the generic overflow test
+            doesn't apply. */
+         tmpfixP->fx_no_overflow = 1;
          break;
        }
 
@@ -2332,11 +2338,18 @@ md_convert_frag (bfd *abfd ATTRIBUTE_UNUSED, segT sec ATTRIBUTE_UNUSED,
     case ENCODE_RELAX (STATE_PUSHJSTUB, STATE_ZERO):
       /* Setting the unknown bits to 0 seems the most appropriate.  */
       mmix_set_geta_branch_offset (opcodep, 0);
-      tmpfixP = fix_new (opc_fragP, opcodep - opc_fragP->fr_literal, 8,
+      tmpfixP = fix_new (opc_fragP, opcodep - opc_fragP->fr_literal, 4,
                         fragP->fr_symbol, fragP->fr_offset, 1,
                         BFD_RELOC_MMIX_PUSHJ_STUBBABLE);
       COPY_FR_WHERE_TO_FX (fragP, tmpfixP);
       var_part_size = 0;
+
+      /* This is a non-trivial fixup; we'll be calling a generated
+        stub, whose address fits into the fixup.  The actual target,
+        as reflected by the fixup value, is further away than fits
+        into the fixup, so the generic overflow test doesn't
+        apply. */
+      tmpfixP->fx_no_overflow = 1;
       break;
 
     case ENCODE_RELAX (STATE_GETA, STATE_ZERO):

diff --git a/gas/config/tc-mmix.h b/gas/config/tc-mmix.h
index d9e8599c888ea1746d638496eca36f63bb7cf006..f7a54c1de26385cb4c918331835c7b4ac7cddf47 100644 (file)
--- a/gas/config/tc-mmix.h
+++ b/gas/config/tc-mmix.h
@@ -226,8 +226,5 @@ extern void mmix_md_do_align (int, char *, int, int);
    explicitly say one byte.  */
 #define DWARF2_LINE_MIN_INSN_LENGTH 1
 
-/* This target is buggy, and sets fix size too large.  */
-#define TC_FX_SIZE_SLACK(FIX) 6
-
 /* MMIX has global register symbols.  */
 #define TC_GLOBAL_REGISTER_SYMBOL_OK