[dev.power64] liblink: improve documentation of struct Prog

LGTM=dave, rsc
R=rsc, dave
CC=golang-codereviews
https://golang.org/cl/169460043

diff --git a/include/link.h b/include/link.h
index c80f467580cd80f2210221e05deacda7112434a1..06f3ebb489408ebd26038c693b89c16e1163c30c 100644 (file)
--- a/include/link.h
+++ b/include/link.h
@@ -54,7 +54,7 @@ struct        Addr
        {
                char    sval[8];
                float64 dval;
-               Prog*   branch; // for 5g, 6g, 8g
+               Prog*   branch; // for 5g, 6g, 8g, 9g
        } u;
 
        LSym*   sym;
@@ -89,10 +89,13 @@ struct      Prog
        int32   lineno;
        Prog*   link;
        short   as;
-       uchar   reg; // arm, power64 only
-       uchar   scond; // arm only
+       uchar   scond; // arm only; condition codes
+
+       // operands
        Addr    from;
-       Addr    from3; // power64 only, fma and rlwm
+       uchar   reg; // arm, power64 only (e.g., ADD from, reg, to);
+                    // also used for ADATA width on arm, power64
+       Addr    from3; // power64 only (e.g., RLWM/FMADD from, reg, from3, to)
        Addr    to;
        
        // for 5g, 6g, 8g internal use