Disassembler: select table based on VEX prefixes

We can use the new VEX prefixes to select into a large table of new
opcode spaces.  Since the table is (currently) sparse, add logic so we
don't end up producing tons of empty tables for no good reason.

This is also necessary since VEX is likely to reuse opcode bytes that
would appear as prefixes at some point, which would cause conflicts
with the regular tables.

1 files changed, 42 insertions, 4 deletions

diff --git a/insns.pl b/insns.pl
index bbb1702..594eec1 100644
--- a/insns.pl
+++ b/insns.pl
@@ -14,6 +14,15 @@
 # This should match MAX_OPERANDS from nasm.h
 $MAX_OPERANDS = 5;
 
+# Add VEX prefixes
+@vexlist = ();
+for ($m = 0; $m < 32; $m++) {
+    for ($lp = 0; $lp < 8; $lp++) {
+	push(@vexlist, sprintf("VEX%02X%01X", $m, $lp));
+    }
+}
+@disasm_prefixes = (@vexlist, @disasm_prefixes);
+
 print STDERR "Reading insns.dat...\n";
 
 @args   = ();
@@ -182,8 +191,20 @@ if ( !defined($output) || $output eq 'd' ) {
 	print D "};\n";
     }
 
+    @prefix_list = ();
     foreach $h (@disasm_prefixes, '') {
-	$is_prefix{$h} = 1;
+	for ($c = 0; $c < 256; $c++) {
+	    $nn = sprintf("%s%02X", $h, $c);
+	    if ($is_prefix{$nn} || defined($dinstables{$nn})) {
+		# At least one entry in this prefix table
+		push(@prefix_list, $h);
+		$is_prefix{$h} = 1;
+		last;
+	    }
+	}
+    }
+
+    foreach $h (@prefix_list) {
 	print D "\n";
 	print D "static " unless ($h eq '');
 	print D "const struct disasm_index ";
@@ -202,8 +223,23 @@ if ( !defined($output) || $output eq 'd' ) {
 		printf D "    { NULL, 0 },\n";
 	    }
 	}
-    print D "};\n";
+	print D "};\n";
+    }
+
+    print D "\nconst struct disasm_index * const itable_VEX[32][8] = {\n";
+    for ($m = 0; $m < 32; $m++) {
+	print D "\t{\n";
+	for ($lp = 0; $lp < 8; $lp++) {
+	    $vp = sprintf("VEX%02X%01X", $m, $lp);
+	    if ($is_prefix{$vp}) {
+		printf D "\t\titable_%s,\n", $vp;
+	    } else {
+		print  D "\t\tNULL,\n";
+	    }
+	}
+	print D "\t},\n";
     }
+    print D "};\n";
 
     close D;
 }
@@ -464,8 +500,10 @@ sub startseq($) {
       } elsif ($c0 == 0 || $c0 == 0340) {
 	  return $prefix;
       } elsif (($c0 & ~3) == 0260 || $c0 == 0270) {
-	  shift(@codes);	# Skip VEX control bytes
-	  shift(@codes);
+	  my $m,$wlp,$vxp;
+	  $m   = shift(@codes);
+	  $wlp = shift(@codes);
+	  $prefix .= sprintf('VEX%02X%01X', $m, $wlp & 7);
       } elsif ($c0 >= 0172 && $c0 <= 174) {
 	  shift(@codes);	# Skip is4 control byte
       } else {