diff --git a/include/opcode/ChangeLog b/include/opcode/ChangeLog
index afc0807ea..dd37f6c90 100644
--- a/include/opcode/ChangeLog
+++ b/include/opcode/ChangeLog
@@ -1,3 +1,12 @@
+2007-11-29  Mark Shinwell  <shinwell@codesourcery.com>
+
+	* mips.h (INSN_ISA*): Redefine certain values as an
+	enumeration.  Update comments.
+	(mips_isa_table): New.
+	(ISA_MIPS*): Redefine to match enumeration.
+	(OPCODE_IS_MEMBER): Modify to correctly test new INSN_ISA*
+	values.
+
 2007-08-08  Ben Elliston  <bje@au.ibm.com>
 
 	* ppc.h (PPC_OPCODE_PPCPS): New.
diff --git a/include/opcode/mips.h b/include/opcode/mips.h
index 71822a41b..d74dccd94 100644
--- a/include/opcode/mips.h
+++ b/include/opcode/mips.h
@@ -472,20 +472,43 @@ struct mips_opcode
 #define INSN_MACRO                  0xffffffff
 
 /* Masks used to mark instructions to indicate which MIPS ISA level
-   they were introduced in.  ISAs, as defined below, are logical
-   ORs of these bits, indicating that they support the instructions
-   defined at the given level.  */
+   they were introduced in.  INSN_ISA_MASK masks an enumeration that
+   specifies the base ISA level(s).  The remainder of a 32-bit
+   word constructed using these macros is a bitmask of the remaining
+   INSN_* values below.  */
 
-#define INSN_ISA_MASK		  0x00000fff
-#define INSN_ISA1                 0x00000001
-#define INSN_ISA2                 0x00000002
-#define INSN_ISA3                 0x00000004
-#define INSN_ISA4                 0x00000008
-#define INSN_ISA5                 0x00000010
-#define INSN_ISA32                0x00000020
-#define INSN_ISA64                0x00000040
-#define INSN_ISA32R2              0x00000080
-#define INSN_ISA64R2              0x00000100
+#define INSN_ISA_MASK		  0x0000000ful
+
+/* We cannot start at zero due to ISA_UNKNOWN below.  */
+#define INSN_ISA1                 1
+#define INSN_ISA2                 2
+#define INSN_ISA3                 3
+#define INSN_ISA4                 4
+#define INSN_ISA5                 5
+#define INSN_ISA32                6
+#define INSN_ISA32R2              7
+#define INSN_ISA64                8
+#define INSN_ISA64R2              9
+/* Below this point the INSN_* values correspond to combinations of ISAs.
+   They are only for use in the opcodes table to indicate membership of
+   a combination of ISAs that cannot be expressed using the usual inclusion
+   ordering on the above INSN_* values.  */
+#define INSN_ISA3_32              10
+#define INSN_ISA3_32R2            11
+#define INSN_ISA4_32              12
+#define INSN_ISA4_32R2            13
+#define INSN_ISA5_32R2            14
+
+/* Given INSN_ISA* values X and Y, where X ranges over INSN_ISA1 through
+   INSN_ISA5_32R2 and Y ranges over INSN_ISA1 through INSN_ISA64R2,
+   this table describes whether at least one of the ISAs described by X
+   is/are implemented by ISA Y.  (Think of Y as the ISA level supported by
+   a particular core and X as the ISA level(s) at which a certain instruction
+   is defined.)  The ISA(s) described by X is/are implemented by Y iff
+   (mips_isa_table[(Y & INSN_ISA_MASK) - 1] >> ((X & INSN_ISA_MASK) - 1)) & 1
+   is non-zero.  */
+static const unsigned int mips_isa_table[] =
+  { 0x0001, 0x0003, 0x0607, 0x1e0f, 0x3e1f, 0x0a23, 0x3e63, 0x3ebf, 0x3fff };
 
 /* Masks used for MIPS-defined ASEs.  */
 #define INSN_ASE_MASK		  0x3c00f000
@@ -533,17 +556,17 @@ struct mips_opcode
 /* MIPS ISA defines, use instead of hardcoding ISA level.  */
 
 #define       ISA_UNKNOWN     0               /* Gas internal use.  */
-#define       ISA_MIPS1       (INSN_ISA1)
-#define       ISA_MIPS2       (ISA_MIPS1 | INSN_ISA2)
-#define       ISA_MIPS3       (ISA_MIPS2 | INSN_ISA3)
-#define       ISA_MIPS4       (ISA_MIPS3 | INSN_ISA4)
-#define       ISA_MIPS5       (ISA_MIPS4 | INSN_ISA5)
+#define       ISA_MIPS1       INSN_ISA1
+#define       ISA_MIPS2       INSN_ISA2
+#define       ISA_MIPS3       INSN_ISA3
+#define       ISA_MIPS4       INSN_ISA4
+#define       ISA_MIPS5       INSN_ISA5
 
-#define       ISA_MIPS32      (ISA_MIPS2 | INSN_ISA32)
-#define       ISA_MIPS64      (ISA_MIPS5 | INSN_ISA32 | INSN_ISA64)
+#define       ISA_MIPS32      INSN_ISA32
+#define       ISA_MIPS64      INSN_ISA64
 
-#define       ISA_MIPS32R2    (ISA_MIPS32 | INSN_ISA32R2)
-#define       ISA_MIPS64R2    (ISA_MIPS64 | INSN_ISA32R2 | INSN_ISA64R2)
+#define       ISA_MIPS32R2    INSN_ISA32R2
+#define       ISA_MIPS64R2    INSN_ISA64R2
 
 
 /* CPU defines, use instead of hardcoding processor number. Keep this
@@ -583,7 +606,12 @@ struct mips_opcode
    test, or zero if no CPU specific ISA test is desired.  */
 
 #define OPCODE_IS_MEMBER(insn, isa, cpu)				\
-    (((insn)->membership & isa) != 0					\
+    (((isa & INSN_ISA_MASK) != 0                                        \
+      && ((insn)->membership & INSN_ISA_MASK) != 0                      \
+      && ((mips_isa_table [(isa & INSN_ISA_MASK) - 1] >>                \
+           (((insn)->membership & INSN_ISA_MASK) - 1)) & 1) != 0)       \
+     || ((isa & ~INSN_ISA_MASK)                                         \
+          & ((insn)->membership & ~INSN_ISA_MASK)) != 0                 \
      || (cpu == CPU_R4650 && ((insn)->membership & INSN_4650) != 0)	\
      || (cpu == CPU_RM7000 && ((insn)->membership & INSN_4650) != 0)	\
      || (cpu == CPU_RM9000 && ((insn)->membership & INSN_4650) != 0)	\