libmach: fix disassembly of FCMOVcc and FCOMI

The optable for 0xDB is handled specially.

This was the cause of a really weird bug
when using cov (386!) on the math package.

A real head-scratcher.

R=rsc
CC=golang-dev
https://golang.org/cl/4639066

src/libmach/8db.c

@@ -1017,14 +1017,56 @@ static Optable optabDB[8+64] =
 [0x03] =	{ 0,0,		"FMOVLP	F0,%e" },
 [0x05] =	{ 0,0,		"FMOVX	%e,F0" },
 [0x07] =	{ 0,0,		"FMOVXP	F0,%e" },
-[0x08] =	{ 0,0,		"FCMOVCC	%f,F0" },
-[0x09] =	{ 0,0,		"FCMOVNE	%f,F0" },
-[0x0a] =	{ 0,0,		"FCMOVHI	%f,F0" },
-[0x0b] =	{ 0,0,		"FCMOVNU	%f,F0" },
-[0x0d] =	{ 0,0,		"FUCOMI	F0,%f" },
-[0x0e] =	{ 0,0,		"FCOMI	F0,%f" },
+[0x08] =	{ 0,0,		"FCMOVCC	F0,F0" },	/* Mod R/M = 11xx xxxx*/
+[0x09] =	{ 0,0,		"FCMOVCC	F1,F0" },
+[0x0a] =	{ 0,0,		"FCMOVCC	F2,F0" },
+[0x0b] =	{ 0,0,		"FCMOVCC	F3,F0" },
+[0x0c] =	{ 0,0,		"FCMOVCC	F4,F0" },
+[0x0d] =	{ 0,0,		"FCMOVCC	F5,F0" },
+[0x0e] =	{ 0,0,		"FCMOVCC	F6,F0" },
+[0x0f] =	{ 0,0,		"FCMOVCC	F7,F0" },
+[0x10] =	{ 0,0,		"FCMOVNE	F0,F0" },
+[0x11] =	{ 0,0,		"FCMOVNE	F1,F0" },
+[0x12] =	{ 0,0,		"FCMOVNE	F2,F0" },
+[0x13] =	{ 0,0,		"FCMOVNE	F3,F0" },
+[0x14] =	{ 0,0,		"FCMOVNE	F4,F0" },
+[0x15] =	{ 0,0,		"FCMOVNE	F5,F0" },
+[0x16] =	{ 0,0,		"FCMOVNE	F6,F0" },
+[0x17] =	{ 0,0,		"FCMOVNE	F7,F0" },
+[0x18] =	{ 0,0,		"FCMOVHI	F0,F0" },
+[0x19] =	{ 0,0,		"FCMOVHI	F1,F0" },
+[0x1a] =	{ 0,0,		"FCMOVHI	F2,F0" },
+[0x1b] =	{ 0,0,		"FCMOVHI	F3,F0" },
+[0x1c] =	{ 0,0,		"FCMOVHI	F4,F0" },
+[0x1d] =	{ 0,0,		"FCMOVHI	F5,F0" },
+[0x1e] =	{ 0,0,		"FCMOVHI	F6,F0" },
+[0x1f] =	{ 0,0,		"FCMOVHI	F7,F0" },
+[0x20] =	{ 0,0,		"FCMOVNU	F0,F0" },
+[0x21] =	{ 0,0,		"FCMOVNU	F1,F0" },
+[0x22] =	{ 0,0,		"FCMOVNU	F2,F0" },
+[0x23] =	{ 0,0,		"FCMOVNU	F3,F0" },
+[0x24] =	{ 0,0,		"FCMOVNU	F4,F0" },
+[0x25] =	{ 0,0,		"FCMOVNU	F5,F0" },
+[0x26] =	{ 0,0,		"FCMOVNU	F6,F0" },
+[0x27] =	{ 0,0,		"FCMOVNU	F7,F0" },
 [0x2a] =	{ 0,0,		"FCLEX" },
 [0x2b] =	{ 0,0,		"FINIT" },
+[0x30] =	{ 0,0,		"FUCOMI	F0,F0" },
+[0x31] =	{ 0,0,		"FUCOMI	F1,F0" },
+[0x32] =	{ 0,0,		"FUCOMI	F2,F0" },
+[0x33] =	{ 0,0,		"FUCOMI	F3,F0" },
+[0x34] =	{ 0,0,		"FUCOMI	F4,F0" },
+[0x35] =	{ 0,0,		"FUCOMI	F5,F0" },
+[0x36] =	{ 0,0,		"FUCOMI	F6,F0" },
+[0x37] =	{ 0,0,		"FUCOMI	F7,F0" },
+[0x38] =	{ 0,0,		"FCOMI	F0,F0" },
+[0x39] =	{ 0,0,		"FCOMI	F1,F0" },
+[0x3a] =	{ 0,0,		"FCOMI	F2,F0" },
+[0x3b] =	{ 0,0,		"FCOMI	F3,F0" },
+[0x3c] =	{ 0,0,		"FCOMI	F4,F0" },
+[0x3d] =	{ 0,0,		"FCOMI	F5,F0" },
+[0x3e] =	{ 0,0,		"FCOMI	F6,F0" },
+[0x3f] =	{ 0,0,		"FCOMI	F7,F0" },
 };
 
 static Optable optabDC[8+8] =