[PATCH v3 1/1] ppc: support register names in macros

[Dmitry Selyutin <ghostmansd@gmail.com>]

This patch is a follow-up of discussion:

https://sourceware.org/pipermail/binutils/2022-July/121719.html

Form now on, PPC assembly becomes capable of compiling such code:

    .set VREG, %r0
    .set REG, VREG
    extsw REG, 2
    extsw %r1, 1

The custom register_name() code path, as well as checks for CRs, are
deprecated; from now on, we use md_operand() routine everywhere.

Whilst we're here, let's also reuse register lookup for CFI.
---
 gas/config/tc-ppc.c | 204 +++++++++++++++++---------------------------
 gas/config/tc-ppc.h |   9 +-
 2 files changed, 82 insertions(+), 131 deletions(-)

diff --git a/gas/config/tc-ppc.c b/gas/config/tc-ppc.c
index 5015777d60..181b1edc4d 100644
--- a/gas/config/tc-ppc.c
+++ b/gas/config/tc-ppc.c
@@ -317,7 +317,7 @@ struct pd_reg
 
    The table is sorted. Suitable for searching by a binary search.  */
 
-static const struct pd_reg pre_defined_registers[] =
+static const struct pd_reg reg_names[] =
 {
   /* VSX accumulators.  */
   { "a0", 0, PPC_OPERAND_ACC },
@@ -784,8 +784,26 @@ static const struct pd_reg pre_defined_registers[] =
 
   { "xer", 1, PPC_OPERAND_SPR }
 };
+#define REG_NAME_CNT	(sizeof (reg_names) / sizeof (struct pd_reg))
 
-#define REG_NAME_CNT	(sizeof (pre_defined_registers) / sizeof (struct pd_reg))
+/* Names to recognize in a condition code.  This table is sorted.  */
+static const struct pd_reg cr_names[] =
+{
+  { "cr0", 0, PPC_OPERAND_CR_REG },
+  { "cr1", 1, PPC_OPERAND_CR_REG },
+  { "cr2", 2, PPC_OPERAND_CR_REG },
+  { "cr3", 3, PPC_OPERAND_CR_REG },
+  { "cr4", 4, PPC_OPERAND_CR_REG },
+  { "cr5", 5, PPC_OPERAND_CR_REG },
+  { "cr6", 6, PPC_OPERAND_CR_REG },
+  { "cr7", 7, PPC_OPERAND_CR_REG },
+  { "eq", 2, PPC_OPERAND_CR_BIT },
+  { "gt", 1, PPC_OPERAND_CR_BIT },
+  { "lt", 0, PPC_OPERAND_CR_BIT },
+  { "so", 3, PPC_OPERAND_CR_BIT },
+  { "un", 3, PPC_OPERAND_CR_BIT }
+};
+#define CR_NAME_CNT	(sizeof (cr_names) / sizeof (struct pd_reg))
 
 /* Given NAME, find the register number associated with that name, return
    the integer value associated with the given name or -1 on failure.  */
@@ -815,83 +833,9 @@ reg_name_search (const struct pd_reg *regs, int regcount, const char *name)
   return NULL;
 }
 
-/*
- * Summary of register_name.
- *
- * in:	Input_line_pointer points to 1st char of operand.
- *
- * out:	A expressionS.
- *      The operand may have been a register: in this case, X_op == O_register,
- *      X_add_number is set to the register number, and truth is returned.
- *	Input_line_pointer->(next non-blank) char after operand, or is in its
- *      original state.
- */
-
-static bool
-register_name (expressionS *expressionP)
-{
-  const struct pd_reg *reg;
-  char *name;
-  char *start;
-  char c;
-
-  /* Find the spelling of the operand.  */
-  start = name = input_line_pointer;
-  if (name[0] == '%' && ISALPHA (name[1]))
-    name = ++input_line_pointer;
-
-  else if (!reg_names_p || !ISALPHA (name[0]))
-    return false;
-
-  c = get_symbol_name (&name);
-  reg = reg_name_search (pre_defined_registers, REG_NAME_CNT, name);
-
-  /* Put back the delimiting char.  */
-  *input_line_pointer = c;
-
-  /* Look to see if it's in the register table.  */
-  if (reg != NULL)
-    {
-      expressionP->X_op = O_register;
-      expressionP->X_add_number = reg->value;
-      expressionP->X_md = reg->flags;
-
-      /* Make the rest nice.  */
-      expressionP->X_add_symbol = NULL;
-      expressionP->X_op_symbol = NULL;
-      return true;
-    }
-
-  /* Reset the line as if we had not done anything.  */
-  input_line_pointer = start;
-  return false;
-}
-\f
-/* This function is called for each symbol seen in an expression.  It
-   handles the special parsing which PowerPC assemblers are supposed
-   to use for condition codes.  */
-
 /* Whether to do the special parsing.  */
 static bool cr_operand;
 
-/* Names to recognize in a condition code.  This table is sorted.  */
-static const struct pd_reg cr_names[] =
-{
-  { "cr0", 0, PPC_OPERAND_CR_REG },
-  { "cr1", 1, PPC_OPERAND_CR_REG },
-  { "cr2", 2, PPC_OPERAND_CR_REG },
-  { "cr3", 3, PPC_OPERAND_CR_REG },
-  { "cr4", 4, PPC_OPERAND_CR_REG },
-  { "cr5", 5, PPC_OPERAND_CR_REG },
-  { "cr6", 6, PPC_OPERAND_CR_REG },
-  { "cr7", 7, PPC_OPERAND_CR_REG },
-  { "eq", 2, PPC_OPERAND_CR_BIT },
-  { "gt", 1, PPC_OPERAND_CR_BIT },
-  { "lt", 0, PPC_OPERAND_CR_BIT },
-  { "so", 3, PPC_OPERAND_CR_BIT },
-  { "un", 3, PPC_OPERAND_CR_BIT }
-};
-
 /* Parsing function.  This returns non-zero if it recognized an
    expression.  */
 
@@ -900,23 +844,51 @@ ppc_parse_name (const char *name, expressionS *exp)
 {
   const struct pd_reg *reg;
 
-  if (! cr_operand)
-    return 0;
-
-  if (*name == '%')
+  if (name[0] == '%' && ISALPHA (name[1]))
     ++name;
-  reg = reg_name_search (cr_names, sizeof cr_names / sizeof cr_names[0],
-			 name);
-  if (reg == NULL)
+  else if (!cr_operand && (!reg_names_p || !ISALPHA (name[0])))
     return 0;
 
-  exp->X_op = O_register;
-  exp->X_add_number = reg->value;
-  exp->X_md = reg->flags;
+  if (cr_operand)
+    reg = reg_name_search (cr_names, CR_NAME_CNT, name);
+  else
+    reg = reg_name_search (reg_names, REG_NAME_CNT, name);
+  if (reg != NULL)
+    {
+      exp->X_op = O_register;
+      exp->X_add_number = reg->value;
+      exp->X_md = reg->flags;
+
+      if (! cr_operand)
+	{
+	  /* Make the rest nice.  */
+	  exp->X_add_symbol = NULL;
+	  exp->X_op_symbol = NULL;
+	}
 
-  return 1;
+      return 1;
+    }
+
+  return 0;
 }
 
+void
+ppc_operand (expressionS *exp)
+{
+  char endc;
+  char *name;
+  char *origin = input_line_pointer;
+
+  endc = get_symbol_name (&name);
+  if (! ppc_parse_name (name, exp))
+    {
+      restore_line_pointer (endc);
+      input_line_pointer = origin;
+    }
+}
+
+\f
+
 /* Propagate X_md and check register expressions.  This is to support
    condition codes like 4*cr5+eq.  */
 
@@ -3437,25 +3409,11 @@ md_assemble (char *str)
       /* Gather the operand.  */
       hold = input_line_pointer;
       input_line_pointer = str;
-
-      if ((reg_names_p
-	   && (((operand->flags & PPC_OPERAND_CR_BIT) != 0)
-	       || ((operand->flags & PPC_OPERAND_CR_REG) != 0)))
-	  || !register_name (&ex))
-	{
-	  char save_lex = lex_type['%'];
-
-	  if (((operand->flags & PPC_OPERAND_CR_REG) != 0)
-	      || (operand->flags & PPC_OPERAND_CR_BIT) != 0)
-	    {
-	      cr_operand = true;
-	      lex_type['%'] |= LEX_BEGIN_NAME;
-	    }
-	  expression (&ex);
-	  cr_operand = false;
-	  lex_type['%'] = save_lex;
-	}
-
+      memset (&ex, 0, sizeof (expressionS));
+      if (operand->flags & (PPC_OPERAND_CR_BIT | PPC_OPERAND_CR_REG))
+	cr_operand = true;
+      expression (&ex);
+      cr_operand = false;
       str = input_line_pointer;
       input_line_pointer = hold;
 
@@ -7734,10 +7692,8 @@ ppc_cfi_frame_initial_instructions (void)
 int
 tc_ppc_regname_to_dw2regnum (char *regname)
 {
-  unsigned int regnum = -1;
   unsigned int i;
-  const char *p;
-  char *q;
+  const struct pd_reg *reg;
   static struct { const char *name; int dw2regnum; } regnames[] =
     {
       { "sp", 1 }, { "r.sp", 1 }, { "rtoc", 2 }, { "r.toc", 2 },
@@ -7750,23 +7706,15 @@ tc_ppc_regname_to_dw2regnum (char *regname)
     if (strcmp (regnames[i].name, regname) == 0)
       return regnames[i].dw2regnum;
 
-  if (regname[0] == 'r' || regname[0] == 'f' || regname[0] == 'v')
-    {
-      p = regname + 1 + (regname[1] == '.');
-      regnum = strtoul (p, &q, 10);
-      if (p == q || *q || regnum >= 32)
-	return -1;
-      if (regname[0] == 'f')
-	regnum += 32;
-      else if (regname[0] == 'v')
-	regnum += 77;
-    }
-  else if (regname[0] == 'c' && regname[1] == 'r')
-    {
-      p = regname + 2 + (regname[2] == '.');
-      if (p[0] < '0' || p[0] > '7' || p[1])
-	return -1;
-      regnum = p[0] - '0' + 68;
-    }
-  return regnum;
+  if (regname[0] == '%' && ISALPHA (regname[1]))
+    ++regname;
+
+  reg = reg_name_search (reg_names, REG_NAME_CNT, regname);
+  if (reg == NULL)
+    reg = reg_name_search (cr_names, CR_NAME_CNT, regname);
+
+  if (reg != NULL)
+    return reg->value;
+
+  return -1;
 }
diff --git a/gas/config/tc-ppc.h b/gas/config/tc-ppc.h
index ed06a29638..da3c427c4a 100644
--- a/gas/config/tc-ppc.h
+++ b/gas/config/tc-ppc.h
@@ -322,14 +322,17 @@ extern void ppc_frob_label (symbolS *);
 /* call md_pcrel_from_section, not md_pcrel_from */
 #define MD_PCREL_FROM_SECTION(FIX, SEC) md_pcrel_from_section(FIX, SEC)
 
+#define LEX_PCT (LEX_BEGIN_NAME)
+
+extern int ppc_parse_name (const char *name, struct expressionS *exp);
 #define md_parse_name(name, exp, mode, c) ppc_parse_name (name, exp)
-extern int ppc_parse_name (const char *, struct expressionS *);
+
+extern void ppc_operand (expressionS *exp);
+#define md_operand ppc_operand
 
 #define md_optimize_expr(left, op, right) ppc_optimize_expr (left, op, right)
 extern int ppc_optimize_expr (expressionS *, operatorT, expressionS *);
 
-#define md_operand(x)
-
 #define md_cleanup() ppc_cleanup ()
 extern void ppc_cleanup (void);
 
-- 
2.37.0