base/asm-common.h: Decorate pseudoregister `nil' as `nil'.

This allows `nil' to be passed through macros which want to apply
decoration transforms to their register arguments through to other
macros which treat `nil' as a special marker that a register is absent
or otherwise not to be used.

diff --git a/base/asm-common.h b/base/asm-common.h
index d162a5d..ebcba2c 100644 (file)
--- a/base/asm-common.h
+++ b/base/asm-common.h
@@ -311,6 +311,7 @@ name:
 // R_r(decor) applies decoration decor to register r, which is an internal
 // register name.  The internal register names are: `ip', `a', `b', `c', `d',
 // `si', `di', `bp', `sp', `r8'--`r15'.
+#define R_nil(decor) nil
 #define R_ip(decor) _DECOR(ip, decor, ip)
 #define R_a(decor) _DECOR(abcd, decor, a)
 #define R_b(decor) _DECOR(abcd, decor, b)
@@ -345,6 +346,8 @@ name:
 // assembler-level register name, in place of any decoration that register
 // name has already.
 
+#define _REGFORM_nil(decor) R_nil(decor)
+
 #define _REGFORM_ip(decor) R_ip(decor)
 #define _REGFORM_eip(decor) R_ip(decor)
 
@@ -667,6 +670,8 @@ name:
 // Internal macros: `_REGFORM_r(decor)' applies decoration decor to register
 // name r.
 
+#define _REGFORM_nil(decor) nil
+
 #define _REGFORM_s0(decor) _DECOR(s, decor, 0)
 #define _REGFORM_s1(decor) _DECOR(s, decor, 1)
 #define _REGFORM_s2(decor) _DECOR(s, decor, 2)