more code optimization

1. dont clear external and heap objects
2. propagate constant assignment

R=r
OCL=28254
CL=28254

diff --git a/src/cmd/6g/peep.c b/src/cmd/6g/peep.c
index c84ff3ce72352c28dcf4df553c8ce116e10bb208..6a12940bab1d955a65f519e842e71d87eda240b1 100644 (file)
--- a/src/cmd/6g/peep.c
+++ b/src/cmd/6g/peep.c
@@ -31,7 +31,9 @@
 #include "gg.h"
 #include "opt.h"
 
+static void    conprop(Reg *r);
 
+// do we need the carry bit
 static int
 needc(Prog *p)
 {
@@ -122,8 +124,34 @@ peep(void)
                }
        }
 
-loop1:
+       // constant propagation
+       // find MOV $con,R followed by
+       // another MOV $con,R without
+       // setting R in the interim
+       for(r=firstr; r!=R; r=r->link) {
+               p = r->prog;
+               switch(p->as) {
+               case ALEAL:
+               case ALEAQ:
+                       if(regtyp(&p->to))
+                       if(p->from.sym != S)
+                               conprop(r);
+                       break;
+
+               case AMOVB:
+               case AMOVW:
+               case AMOVL:
+               case AMOVQ:
+               case AMOVSS:
+               case AMOVSD:
+                       if(regtyp(&p->to))
+                       if(p->from.type == D_CONST)
+                               conprop(r);
+                       break;
+               }
+       }
 
+loop1:
        if(debug['P'] && debug['v'])
                dumpit("loop1", firstr);
 
@@ -196,8 +224,8 @@ loop1:
                                else
                                        p->as = ADECW;
                                p->from = zprog.from;
+                               break;
                        }
-                       else
                        if(p->from.offset == 1){
                                if(p->as == AADDQ)
                                        p->as = AINCQ;
@@ -206,6 +234,7 @@ loop1:
                                else
                                        p->as = AINCW;
                                p->from = zprog.from;
+                               break;
                        }
                        break;
 
@@ -223,8 +252,8 @@ loop1:
                                else
                                        p->as = AINCW;
                                p->from = zprog.from;
+                               break;
                        }
-                       else
                        if(p->from.offset == 1){
                                if(p->as == ASUBQ)
                                        p->as = ADECQ;
@@ -234,6 +263,7 @@ loop1:
                                else
                                        p->as = ADECW;
                                p->from = zprog.from;
+                               break;
                        }
                        break;
                }
@@ -905,3 +935,49 @@ copysub(Adr *a, Adr *v, Adr *s, int f)
        }
        return 0;
 }
+
+static void
+conprop(Reg *r0)
+{
+       Reg *r;
+       Prog *p, *p0;
+       int t;
+       Adr *v0;
+
+       p0 = r0->prog;
+       v0 = &p0->to;
+       r = r0;
+
+loop:
+       r = uniqs(r);
+       if(r == R || r == r0)
+               return;
+       if(uniqp(r) == R)
+               return;
+
+       p = r->prog;
+       t = copyu(p, v0, A);
+       switch(t) {
+       case 0: // miss
+       case 1: // use
+               goto loop;
+
+       case 2: // rar
+       case 4: // use and set
+               break;
+
+       case 3: // set
+               if(p->as == p0->as)
+               if(p->from.type == p0->from.type)
+               if(p->from.sym == p0->from.sym)
+               if(p->from.offset == p0->from.offset)
+               if(p->from.scale == p0->from.scale)
+               if(p->from.dval == p0->from.dval)
+               if(p->from.index == p0->from.index) {
+                       excise(r);
+                       t++;
+                       goto loop;
+               }
+               break;
+       }
+}

diff --git a/src/cmd/gc/gen.c b/src/cmd/gc/gen.c
index 410c1a5194098f440cba9f65cef4c31bdc03f335..249d0fde05b4d6afd15b8bc817372f9813a7ee6e 100644 (file)
--- a/src/cmd/gc/gen.c
+++ b/src/cmd/gc/gen.c
@@ -437,6 +437,12 @@ cgen_as(Node *nl, Node *nr)
                        cgen_as(nl->right, nr);
                        return;
                }
+
+               // externals and heaps should already be clear
+               if(nl->class == PEXTERN)
+                       return;
+               if(nl->class & PHEAP)
+                       return;
                tl = nl->type;
                if(tl == T)
                        return;