[gcc r12-836] Improve message for wrong number of alternatives.

[gcc r12-836] Improve message for wrong number of alternatives.

[Joern Rennecke]

https://gcc.gnu.org/g:bdd8e3dd60c4f6080df74fe02b6579451fda6a21

commit r12-836-gbdd8e3dd60c4f6080df74fe02b6579451fda6a21
Author: Joern Rennecke <joern.rennecke@embecosm.com>
Date:   Mon May 17 13:44:49 2021 +0100

    Improve message for wrong number of alternatives.
    
    gcc/
            * genoutput.c (validate_insn_alternatives) Make "wrong number of
            alternatives" message more specific, and remove assumption on where
            the problem is.

Diff:
---
 gcc/genoutput.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/gcc/genoutput.c b/gcc/genoutput.c
index 8e911cce2f5..6d4ab812696 100644
--- a/gcc/genoutput.c
+++ b/gcc/genoutput.c
@@ -757,6 +757,7 @@ validate_insn_alternatives (class data *d)
 	int which_alternative = 0;
 	int alternative_count_unsure = 0;
 	bool seen_write = false;
+	bool alt_mismatch = false;
 
 	for (p = d->operand[start].constraint; (c = *p); p += len)
 	  {
@@ -813,8 +814,19 @@ validate_insn_alternatives (class data *d)
 	    if (n == 0)
 	      n = d->operand[start].n_alternatives;
 	    else if (n != d->operand[start].n_alternatives)
-	      error_at (d->loc, "wrong number of alternatives in operand %d",
-			start);
+	      {
+		if (!alt_mismatch)
+		  {
+		    alt_mismatch = true;
+		    error_at (d->loc,
+			      "alternative number mismatch: "
+			      "operand %d has %d, operand %d has %d",
+			      0, n, start, d->operand[start].n_alternatives);
+		  }
+		else
+		  error_at (d->loc, "operand %d has %d alternatives",
+		    start, d->operand[start].n_alternatives);
+	      }
 	  }
       }