[PATCH] x86/APX: convert runtime special case to build-time one

[Jan Beulich]

cpu_flags_match() is a hot path. Move the special casing that
b7267244a355 ("Support Intel AMX-MOVRS") added there to i386-gen, thus
affecting only build time performance.

--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -2262,14 +2262,6 @@ cpu_flags_match (const insn_template *t)
 	     the "if()" below.  */
 	  gas_assert (!cpu_flags_all_zero (&all));
 
-	  /* For APX_F extension of multiple cpuid enabled insns, we could not
-	     use APX_F(cpuid_A&cpuid_B) since the transformation could not be
-	     done. Instead, we will use cpuid_A & APX_F(cpuid_B), then the
-	     "any" bitfield would not be set for cpuid_A. Set cpuid_A for "any"
-	     here since it is its original meaning.  */
-	  if (all.bitfield.cpuamx_transpose && any.bitfield.cpuamx_movrs)
-	    any.bitfield.cpuamx_transpose = 1;
-
 	  cpu = cpu_flags_and (all, any);
 	  gas_assert (cpu_flags_equal (&cpu, &all));
 
--- a/opcodes/i386-gen.c
+++ b/opcodes/i386-gen.c
@@ -1039,6 +1039,20 @@ process_i386_cpu_flag (FILE *table, char
 	  all[Cpu64].value = 1;
 
       output_cpu_flags(table, all, ARRAY_SIZE (all), -1, comma, indent, lineno);
+
+      /* For APX_F extension of multiple cpuid enabled insns, we cannot use
+	 APX_F(cpuid_A&cpuid_B) in the opcode table, as the result would fail
+	 to be parsed.  Furthermore, the result also wouldn't be quite valid.
+	 However, the assembler's cpu_flags_match() will simply propagate "any"
+	 to "all", zapping "any" afterwards altogether.  IOW in this situation
+	 both masks have "&&" meaning.  Set the missing flag here.  */
+      if (all[CpuAMX_TRANSPOSE].value && all[CpuAMX_MOVRS].value)
+	{
+	  if (!any[CpuAPX_F].value || !any[CpuAMX_MOVRS].value)
+	    fail ("%s: %d: internal error: APX_F=%d AMX_MOVRS=%d\n",
+		  filename, lineno, any[CpuAPX_F].value, any[CpuAMX_MOVRS].value);
+	  any[CpuAMX_TRANSPOSE].value = 1;
+	}
     }
 
   output_cpu_flags (table, any, ARRAY_SIZE (any), name != NULL,