cmd/5g, cmd/8g: registerize small structs and arrays

cmd/6g has been doing this for a long time.

Arrays are still problematic on 5g because the addressing
for t[0] where local var t has type [3]uintptr takes the address of t.
That's issue 8125.

Fixes #8123.

LGTM=josharian
R=josharian, dave
CC=golang-codereviews
https://golang.org/cl/102890046

diff --git a/src/cmd/5g/cgen.c b/src/cmd/5g/cgen.c
index a42e67bafbbc98774753d8055ed95d22f6a5ad63..a9c597cdc819152dca466da0bf68b02a0889725c 100644 (file)
--- a/src/cmd/5g/cgen.c
+++ b/src/cmd/5g/cgen.c
@@ -1635,7 +1635,10 @@ int
 componentgen(Node *nr, Node *nl)
 {
        Node nodl, nodr, tmp;
+       Type *t;
        int freel, freer;
+       vlong fldcount;
+       vlong loffset, roffset;
 
        freel = 0;
        freer = 0;
@@ -1645,8 +1648,33 @@ componentgen(Node *nr, Node *nl)
                goto no;
 
        case TARRAY:
-               if(!isslice(nl->type))
+               t = nl->type;
+
+               // Slices are ok.
+               if(isslice(t))
+                       break;
+               // Small arrays are ok.
+               if(t->bound > 0 && t->bound <= 3 && !isfat(t->type))
+                       break;
+
+               goto no;
+
+       case TSTRUCT:
+               // Small structs with non-fat types are ok.
+               // Zero-sized structs are treated separately elsewhere.
+               fldcount = 0;
+               for(t=nl->type->type; t; t=t->down) {
+                       if(isfat(t->type))
+                               goto no;
+                       if(t->etype != TFIELD)
+                               fatal("componentgen: not a TFIELD: %lT", t);
+                       fldcount++;
+               }
+               if(fldcount == 0 || fldcount > 4)
                        goto no;
+
+               break;
+
        case TSTRING:
        case TINTER:
                break;
@@ -1674,6 +1702,7 @@ componentgen(Node *nr, Node *nl)
                freer = 1;
        }
 
+       
        // nl and nr are 'cadable' which basically means they are names (variables) now.
        // If they are the same variable, don't generate any code, because the
        // VARDEF we generate will mark the old value as dead incorrectly.
@@ -1683,8 +1712,25 @@ componentgen(Node *nr, Node *nl)
 
        switch(nl->type->etype) {
        case TARRAY:
+               // componentgen for arrays.
                if(nl->op == ONAME)
                        gvardef(nl);
+               t = nl->type;
+               if(!isslice(t)) {
+                       nodl.type = t->type;
+                       nodr.type = nodl.type;
+                       for(fldcount=0; fldcount < t->bound; fldcount++) {
+                               if(nr == N)
+                                       clearslim(&nodl);
+                               else
+                                       gmove(&nodr, &nodl);
+                               nodl.xoffset += t->type->width;
+                               nodr.xoffset += t->type->width;
+                       }
+                       goto yes;
+               }
+
+               // componentgen for slices.
                nodl.xoffset += Array_array;
                nodl.type = ptrto(nl->type->type);
 
@@ -1759,6 +1805,31 @@ componentgen(Node *nr, Node *nl)
                gmove(&nodr, &nodl);
 
                goto yes;
+
+       case TSTRUCT:
+               if(nl->op == ONAME)
+                       gvardef(nl);
+               loffset = nodl.xoffset;
+               roffset = nodr.xoffset;
+               // funarg structs may not begin at offset zero.
+               if(nl->type->etype == TSTRUCT && nl->type->funarg && nl->type->type)
+                       loffset -= nl->type->type->width;
+               if(nr != N && nr->type->etype == TSTRUCT && nr->type->funarg && nr->type->type)
+                       roffset -= nr->type->type->width;
+
+               for(t=nl->type->type; t; t=t->down) {
+                       nodl.xoffset = loffset + t->width;
+                       nodl.type = t->type;
+
+                       if(nr == N)
+                               clearslim(&nodl);
+                       else {
+                               nodr.xoffset = roffset + t->width;
+                               nodr.type = nodl.type;
+                               gmove(&nodr, &nodl);
+                       }
+               }
+               goto yes;
        }
 
 no:

diff --git a/src/cmd/8g/cgen.c b/src/cmd/8g/cgen.c
index 5988a4328c9fd98fa682596fe9048eb66a3e21fc..bdf728dbbc6e62e432aa1de1cdabb9180acafadf 100644 (file)
--- a/src/cmd/8g/cgen.c
+++ b/src/cmd/8g/cgen.c
@@ -1367,7 +1367,10 @@ int
 componentgen(Node *nr, Node *nl)
 {
        Node nodl, nodr;
+       Type *t;
        int freel, freer;
+       vlong fldcount;
+       vlong loffset, roffset;
 
        freel = 0;
        freer = 0;
@@ -1377,8 +1380,33 @@ componentgen(Node *nr, Node *nl)
                goto no;
 
        case TARRAY:
-               if(!isslice(nl->type))
+               t = nl->type;
+
+               // Slices are ok.
+               if(isslice(t))
+                       break;
+               // Small arrays are ok.
+               if(t->bound > 0 && t->bound <= 3 && !isfat(t->type))
+                       break;
+
+               goto no;
+
+       case TSTRUCT:
+               // Small structs with non-fat types are ok.
+               // Zero-sized structs are treated separately elsewhere.
+               fldcount = 0;
+               for(t=nl->type->type; t; t=t->down) {
+                       if(isfat(t->type))
+                               goto no;
+                       if(t->etype != TFIELD)
+                               fatal("componentgen: not a TFIELD: %lT", t);
+                       fldcount++;
+               }
+               if(fldcount == 0 || fldcount > 4)
                        goto no;
+
+               break;
+
        case TSTRING:
        case TINTER:
                break;
@@ -1399,7 +1427,7 @@ componentgen(Node *nr, Node *nl)
                        freer = 1;
                }
        }
-
+       
        // nl and nr are 'cadable' which basically means they are names (variables) now.
        // If they are the same variable, don't generate any code, because the
        // VARDEF we generate will mark the old value as dead incorrectly.
@@ -1409,8 +1437,25 @@ componentgen(Node *nr, Node *nl)
 
        switch(nl->type->etype) {
        case TARRAY:
+               // componentgen for arrays.
                if(nl->op == ONAME)
                        gvardef(nl);
+               t = nl->type;
+               if(!isslice(t)) {
+                       nodl.type = t->type;
+                       nodr.type = nodl.type;
+                       for(fldcount=0; fldcount < t->bound; fldcount++) {
+                               if(nr == N)
+                                       clearslim(&nodl);
+                               else
+                                       gmove(&nodr, &nodl);
+                               nodl.xoffset += t->type->width;
+                               nodr.xoffset += t->type->width;
+                       }
+                       goto yes;
+               }
+
+               // componentgen for slices.
                nodl.xoffset += Array_array;
                nodl.type = ptrto(nl->type->type);
 
@@ -1422,7 +1467,7 @@ componentgen(Node *nr, Node *nl)
                gmove(&nodr, &nodl);
 
                nodl.xoffset += Array_nel-Array_array;
-               nodl.type = types[TUINT32];
+               nodl.type = types[simtype[TUINT]];
 
                if(nr != N) {
                        nodr.xoffset += Array_nel-Array_array;
@@ -1432,7 +1477,7 @@ componentgen(Node *nr, Node *nl)
                gmove(&nodr, &nodl);
 
                nodl.xoffset += Array_cap-Array_nel;
-               nodl.type = types[TUINT32];
+               nodl.type = types[simtype[TUINT]];
 
                if(nr != N) {
                        nodr.xoffset += Array_cap-Array_nel;
@@ -1457,7 +1502,7 @@ componentgen(Node *nr, Node *nl)
                gmove(&nodr, &nodl);
 
                nodl.xoffset += Array_nel-Array_array;
-               nodl.type = types[TUINT32];
+               nodl.type = types[simtype[TUINT]];
 
                if(nr != N) {
                        nodr.xoffset += Array_nel-Array_array;
@@ -1492,6 +1537,31 @@ componentgen(Node *nr, Node *nl)
                gmove(&nodr, &nodl);
 
                goto yes;
+
+       case TSTRUCT:
+               if(nl->op == ONAME)
+                       gvardef(nl);
+               loffset = nodl.xoffset;
+               roffset = nodr.xoffset;
+               // funarg structs may not begin at offset zero.
+               if(nl->type->etype == TSTRUCT && nl->type->funarg && nl->type->type)
+                       loffset -= nl->type->type->width;
+               if(nr != N && nr->type->etype == TSTRUCT && nr->type->funarg && nr->type->type)
+                       roffset -= nr->type->type->width;
+
+               for(t=nl->type->type; t; t=t->down) {
+                       nodl.xoffset = loffset + t->width;
+                       nodl.type = t->type;
+
+                       if(nr == N)
+                               clearslim(&nodl);
+                       else {
+                               nodr.xoffset = roffset + t->width;
+                               nodr.type = nodl.type;
+                               gmove(&nodr, &nodl);
+                       }
+               }
+               goto yes;
        }
 
 no: