x86: create function to check miscreg validity

In the process of trying to get rid of an '== false' comparison,
it became apparent that a slightly more involved solution was
needed.  Split this out into its own changeset since it's not
a totally trivial local change like the others.

1 files changed, 10 insertions, 1 deletions

diff --git a/src/arch/x86/regs/misc.hh b/src/arch/x86/regs/misc.hh
index 77f4e1bcd..48f7d974d 100644
--- a/src/arch/x86/regs/misc.hh
+++ b/src/arch/x86/regs/misc.hh
@@ -101,7 +101,7 @@ namespace X86ISA
     enum MiscRegIndex
     {
         // Control registers
-        // Most of these are invalid.
+        // Most of these are invalid.  See isValidMiscReg() below.
         MISCREG_CR_BASE,
         MISCREG_CR0 = MISCREG_CR_BASE,
         MISCREG_CR1,
@@ -399,6 +399,15 @@ namespace X86ISA
         NUM_MISCREGS
     };
 
+    static inline bool
+    isValidMiscReg(int index)
+    {
+        return (index >= MISCREG_CR0 && index < NUM_MISCREGS &&
+                index != MISCREG_CR1 &&
+                !(index > MISCREG_CR4 && index < MISCREG_CR8) &&
+                !(index > MISCREG_CR8 && index <= MISCREG_CR15));
+    }
+
     static inline MiscRegIndex
     MISCREG_CR(int index)
     {