x86: don't mistake ordinary immediates for SAE / rounding control

The way SAE templates are constructed was always puzzling me (including
the need for separate templates in the first place), and expressing the
extzra attribute via Imm8 actually has a bad effect: Ordinary immediates
would also be accepted, leading to an extra byte being added after the
instruction (i.e. generating bad code). Before re-working this (in
particular to accept proper Intel syntax there), fix the immediate issue
by adding the so far missing check.

gas/config/tc-i386.c

@@ -6287,6 +6287,11 @@ check_VecOperands (const insn_template *t)
 	  return 1;
 	}
     }
+  else if (t->opcode_modifier.sae)
+    {
+	i.error = unsupported_syntax;
+	return 1;
+    }
 
   /* Check the special Imm4 cases; must be the first operand.  */
   if (t->cpu_flags.bitfield.cpuxop && t->operands == 5)

gas/testsuite/gas/i386/inval-avx512f.l

@@ -218,6 +218,8 @@
 .*:313: Error: .*unsupported broadcast for `vcvtneps2bf16'
 .*:316: Error: .*unsupported broadcast for `vcvtneps2bf16'
 .*:319: Error: .*unsupported broadcast for `vcvtneps2bf16'
+.*:321: Error: .*vaddps.*
+.*:322: Error: .*vcmpss.*
 GAS LISTING .*
 
 
@@ -569,6 +571,7 @@ GAS LISTING .*
 [ 	]*318 \?\?\?\? 62F27E38[ 	]+vcvtneps2bf16 \(%eax\)\{1to8\}, %xmm1
 [ 	]*318[ 	]+7208
 [ 	]*319[ 	]+vcvtneps2bf16 \(%eax\)\{1to16\}, %xmm1
-[ 	]*320[ 	]+\?\?\?\? 8DB42600 		\.p2align 4
-[ 	]*320[ 	]+0000008D 
-[ 	]*320[ 	]+7600
+[ 	]*320[ 	]*
+[ 	]*321[ 	]+vaddps \$0xcc, %zmm0, %zmm0, %zmm0
+[ 	]*322[ 	]+vcmpss \$0, \$0xcc, %xmm0, %xmm0, %k0
+#pass

gas/testsuite/gas/i386/inval-avx512f.s

@@ -317,4 +317,8 @@ _start:
 	vcvtneps2bf16 (%eax){1to4}, %xmm1
 	vcvtneps2bf16 (%eax){1to8}, %xmm1
 	vcvtneps2bf16 (%eax){1to16}, %xmm1
+
+	vaddps $0xcc, %zmm0, %zmm0, %zmm0
+	vcmpss $0, $0xcc, %xmm0, %xmm0, %k0
+
 	.p2align 4