[binutils-gdb] gas/symbols: introduce md_resolve_symbol

[binutils-gdb] gas/symbols: introduce md_resolve_symbol

[Alan Modra]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=ffd29c9c21422ddacdd66ead68ee060ac01a28c5

commit ffd29c9c21422ddacdd66ead68ee060ac01a28c5
Author: Dmitry Selyutin <ghostmansd@gmail.com>
Date:   Mon Jul 18 12:46:53 2022 +0300

    gas/symbols: introduce md_resolve_symbol
    
    Assuming GMSD is a special operand, marked as O_md1, the code:
    
        .set VREG, GMSD
        .set REG, VREG
        extsw REG, 2
    
    ...fails upon attempts to resolve the value of the symbol. This happens
    since machine-dependent values are not handled in the giant op switch.
    We introduce a custom md_resolve_symbol macro; the ports can use this
    macro to customize the behavior when resolve_symbol_value hits O_md
    operand.

Diff:
---
 gas/doc/internals.texi |  6 ++++++
 gas/symbols.c          | 39 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+)

diff --git a/gas/doc/internals.texi b/gas/doc/internals.texi
index 9221801f635..59b2d3acee5 100644
--- a/gas/doc/internals.texi
+++ b/gas/doc/internals.texi
@@ -1034,6 +1034,12 @@ Predefined symbols with fixed values, such as register names or condition
 codes, are typically entered directly into the symbol table when @code{md_begin}
 is called.  One argument is passed, a @code{char *} for the symbol.
 
+@item md_resolve_symbol
+@cindex md_resolve_symbol
+If this macro is defined, GAS will call it upon resolving machine-dependent
+symbols (that is, for any symbol with operation O_md1..O_md32 inclusively).
+If this functions returns zero, then the symbol could not be resolved.
+
 @item md_operand
 @cindex md_operand
 GAS will call this function with one argument, an @code{expressionS}
diff --git a/gas/symbols.c b/gas/symbols.c
index 6904a3102cf..81383a5e8cb 100644
--- a/gas/symbols.c
+++ b/gas/symbols.c
@@ -1408,6 +1408,45 @@ resolve_symbol_value (symbolS *symp)
 	  BAD_CASE (op);
 	  break;
 
+	case O_md1:
+	case O_md2:
+	case O_md3:
+	case O_md4:
+	case O_md5:
+	case O_md6:
+	case O_md7:
+	case O_md8:
+	case O_md9:
+	case O_md10:
+	case O_md11:
+	case O_md12:
+	case O_md13:
+	case O_md14:
+	case O_md15:
+	case O_md16:
+	case O_md17:
+	case O_md18:
+	case O_md19:
+	case O_md20:
+	case O_md21:
+	case O_md22:
+	case O_md23:
+	case O_md24:
+	case O_md25:
+	case O_md26:
+	case O_md27:
+	case O_md28:
+	case O_md29:
+	case O_md30:
+	case O_md31:
+	case O_md32:
+#ifdef md_resolve_symbol
+	  resolved = md_resolve_symbol (symp, &final_val, &final_seg);
+	  if (resolved)
+	    break;
+#endif
+	  goto exit_dont_set_value;
+
 	case O_absent:
 	  final_val = 0;
 	  /* Fall through.  */