Clarify comment over amd64 fixnum_shift hook.

diff --git a/src/microcode/cmpauxmd/x86-64.m4 b/src/microcode/cmpauxmd/x86-64.m4
index 7a4856dc92e6530d5a9471df01902d0789db24c1..d47d0bc154e8c0f5dcbe889fd848c1284f3ce567 100644 (file)
--- a/src/microcode/cmpauxmd/x86-64.m4
+++ b/src/microcode/cmpauxmd/x86-64.m4
@@ -931,9 +931,9 @@ define_jump_indirection(generic_modulo,39)
 \f
 # Input and output in rax, shift count in rcx, all detagged fixnums.
 # Return address is at the top of the stack, untagged.  This hook must
-# not use any registers other than rax and rcx; if it does, the code
-# to generate calls to it, in compiler/machines/x86-64/rulfix.scm,
-# must clear the register map first.
+# not write to any register other than rax; if it does, the code to
+# generate calls to it, in compiler/machines/x86-64/rulfix.scm, must
+# clear the register map first.
 
 define_hook_label(fixnum_shift)
        OP(sar,q)       TW(IMM(TC_LENGTH),REG(rcx))