Hack around problem that shll can't be converted to addl in front of certain

branches because addl and shll set the N bit differently; outside of this
situation, turn more shll's into addl's.

SCCS-vsn: old/pcc/c2.tahoe/c21.c 1.10

diff --git a/usr/src/old/pcc/c2.tahoe/c21.c b/usr/src/old/pcc/c2.tahoe/c21.c
index 169e451..9659031 100644 (file)
--- a/usr/src/old/pcc/c2.tahoe/c21.c
+++ b/usr/src/old/pcc/c2.tahoe/c21.c
@@ -1,5 +1,5 @@
 #ifndef lint
 #ifndef lint

-static char sccsid[] = "@(#)c21.c      1.9 (Berkeley/CCI) %G%";
+static char sccsid[] = "@(#)c21.c      1.10 (Berkeley/CCI) %G%";

 #endif
 
 /*
 #endif
 
 /*


@@ -294,8 +294,8 @@ bmove() {
                        }
                        pf->pop = 0;
                        redunm++; nsaddr++;
                        }
                        pf->pop = 0;
                        redunm++; nsaddr++;

+                       goto std;

                }
                }

-               goto std;

 ashadd:
                /* at this point, RT2 and RT3 are guaranteed to be simple regs*/
                if (shcnt == 1) {
 ashadd:
                /* at this point, RT2 and RT3 are guaranteed to be simple regs*/
                if (shcnt == 1) {


@@ -304,6 +304,16 @@ ashadd:
                        **      shll    $1,A,A  >       addl2   A,A
                        **      shll    $1,A,B  >       addl3   A,A,B
                        */
                        **      shll    $1,A,A  >       addl2   A,A
                        **      shll    $1,A,B  >       addl3   A,A,B
                        */

+                       if ((pf = p->forw)->op == CBR ||
+                           (pf->op == MOV && (pf = pf->forw)->op == CBR))
+                               /*
+                               ** shll and addl handle the N bit differently
+                               ** on overflow; avoid N bit CBRs
+                               */
+                               switch (pf->subop) {
+                               case JLE: case JGE: case JLT: case JGT:
+                                       goto std;
+                               }

                        p->op = ADD;
                        strcpy(regs[RT1], regs[RT2]);
                        if(equstr(regs[RT2], regs[RT3])) {
                        p->op = ADD;
                        strcpy(regs[RT1], regs[RT2]);
                        if(equstr(regs[RT2], regs[RT3])) {