x86: make code size vs CPU arch checking consistent

While update_code_flag() checks for LM / i386, set_cpu_arch() so far
didn't, allowing e.g. 64-bit code to be emitted after ".arch generic32".

Oddly enough a few of our testcases actually exhibit bad behavior (and
hence need minor adjustments).

gas/config/tc-i386.c

@@ -2928,6 +2928,24 @@ set_cpu_arch (int dummy ATTRIBUTE_UNUSED)
 	    {
 	      check_cpu_arch_compatible (string, cpu_arch[j].enable);
 
+	      if (flag_code == CODE_64BIT && !cpu_arch[j].enable.bitfield.cpulm )
+		{
+		  as_bad (_("64bit mode not supported on `%s'."),
+			  cpu_arch[j].name);
+		  (void) restore_line_pointer (e);
+		  ignore_rest_of_line ();
+		  return;
+		}
+
+	      if (flag_code == CODE_32BIT && !cpu_arch[j].enable.bitfield.cpui386)
+		{
+		  as_bad (_("32bit mode not supported on `%s'."),
+			  cpu_arch[j].name);
+		  (void) restore_line_pointer (e);
+		  ignore_rest_of_line ();
+		  return;
+		}
+
 	      cpu_arch_name = cpu_arch[j].name;
 	      free (cpu_sub_arch_name);
 	      cpu_sub_arch_name = NULL;

gas/testsuite/gas/i386/287.s

@@ -1,9 +1,9 @@
 # Check 287-only instructions.
 
 	.text
+	.code16
 	.arch i286
 	.arch .287
-	.code16
 _8087:
 	fnsetpm
 	frstpm

gas/testsuite/gas/i386/8087.s

@@ -1,9 +1,9 @@
 # Check 8087-only instructions.
 
 	.text
+	.code16
 	.arch i8086
 	.arch .8087
-	.code16
 _8087:
 	fdisi
 	feni

gas/testsuite/gas/i386/att-regs.s

@@ -1,8 +1,8 @@
 	.text
 	.att_syntax noprefix
 
-	.arch i286
 	.code16
+	.arch i286
 	mov	eax, ax			; add	al, (bx,si)
 	mov	rax, ax			; add	al, (bx,si)
 	mov	axl, ax			; add	al, (bx,si)

gas/testsuite/gas/i386/intel-regs.s

@@ -3,8 +3,8 @@
 
 	mov	eax, tmm1
 
-	.arch i286
 	.code16
+	.arch i286
 	mov	ax, eax			; add	[bx+si], al
 	mov	ax, rax			; add	[bx+si], al
 	mov	ax, axl			; add	[bx+si], al

gas/testsuite/gas/i386/inval-16.l

@@ -10,7 +10,7 @@ GAS LISTING .*
 
 
 [ 	]*1[ 	]+\.text
-[ 	]*2[ 	]+\.arch i186; \.code16
+[ 	]*2[ 	]+\.code16; \.arch i186
 [ 	]*3[ 	]+vmovapd	%xmm0,%xmm1
 [ 	]*4[ 	]+vaddsd	%xmm4, %xmm5, %xmm6\{%k7\}
 [ 	]*5[ 	]+vfrczpd	%xmm7,%xmm7

gas/testsuite/gas/i386/inval-16.s

@@ -1,5 +1,5 @@
 	.text
-	.arch i186; .code16
+	.code16; .arch i186
 	vmovapd	%xmm0,%xmm1
 	vaddsd	%xmm4, %xmm5, %xmm6{%k7}
 	vfrczpd	%xmm7,%xmm7

gas/testsuite/gas/i386/nops-5.s

@@ -1,4 +1,5 @@
 	.text
+	.code32
 	.arch i386
 i386:
 	movsbl %al,%esi