6g: avoid too-large immediate constants

R=ken2
CC=golang-dev
https://golang.org/cl/2566042

diff --git a/src/cmd/6g/cgen.c b/src/cmd/6g/cgen.c
index 8c6bfd99b8ff00805238b739bb36afef0649de20..1df6b25dd26f37ded629cd7985cae5281537e576 100644 (file)
--- a/src/cmd/6g/cgen.c
+++ b/src/cmd/6g/cgen.c
@@ -537,9 +537,7 @@ agen(Node *n, Node *res)
                                gmove(&n1, &n3);
                        }
 
-                       nodconst(&n2, types[tptr], v*w);
-                       gins(optoas(OADD, types[tptr]), &n2, &n3);
-
+                       ginscon(optoas(OADD, types[tptr]), v*w, &n3);
                        gmove(&n3, res);
                        regfree(&n3);
                        break;
@@ -596,8 +594,7 @@ agen(Node *n, Node *res)
                        p1->from.index = p1->from.type;
                        p1->from.type = p1->to.type + D_INDIR;
                } else {
-                       nodconst(&n1, t, w);
-                       gins(optoas(OMUL, t), &n1, &n2);
+                       ginscon(optoas(OMUL, t), w, &n2);
                        gins(optoas(OADD, types[tptr]), &n2, &n3);
                        gmove(&n3, res);
                }
@@ -621,10 +618,8 @@ agen(Node *n, Node *res)
                        fatal("agen: bad ONAME class %#x", n->class);
                }
                cgen(n->heapaddr, res);
-               if(n->xoffset != 0) {
-                       nodconst(&n1, types[TINT64], n->xoffset);
-                       gins(optoas(OADD, types[tptr]), &n1, res);
-               }
+               if(n->xoffset != 0)
+                       ginscon(optoas(OADD, types[tptr]), n->xoffset, res);
                break;
 
        case OIND:
@@ -633,10 +628,8 @@ agen(Node *n, Node *res)
 
        case ODOT:
                agen(nl, res);
-               if(n->xoffset != 0) {
-                       nodconst(&n1, types[TINT64], n->xoffset);
-                       gins(optoas(OADD, types[tptr]), &n1, res);
-               }
+               if(n->xoffset != 0)
+                       ginscon(optoas(OADD, types[tptr]), n->xoffset, res);
                break;
 
        case ODOTPTR:
@@ -653,8 +646,7 @@ agen(Node *n, Node *res)
                                gins(ATESTB, nodintconst(0), &n1);
                                regfree(&n1);
                        }
-                       nodconst(&n1, types[TINT64], n->xoffset);
-                       gins(optoas(OADD, types[tptr]), &n1, res);
+                       ginscon(optoas(OADD, types[tptr]), n->xoffset, res);
                }
                break;
        }

diff --git a/src/cmd/6g/gg.h b/src/cmd/6g/gg.h
index d578d675295664ca280be5c9f8125b02aaa39567..7efb2c2528eb1c281f9728f62abc74129df961f4 100644 (file)
--- a/src/cmd/6g/gg.h
+++ b/src/cmd/6g/gg.h
@@ -123,6 +123,7 @@ Node*       nodarg(Type*, int);
 void   nodreg(Node*, Type*, int);
 void   nodindreg(Node*, Type*, int);
 void   gconreg(int, vlong, int);
+void   ginscon(int, vlong, Node*);
 void   buildtxt(void);
 Plist* newplist(void);
 int    isfat(Type*);

diff --git a/src/cmd/6g/ggen.c b/src/cmd/6g/ggen.c
index 6d005d7ece38cdb11d3a73a864874514a3c2b4d4..ebee6f81038a52a5968d41fe0189f1b1d227c094 100644 (file)
--- a/src/cmd/6g/ggen.c
+++ b/src/cmd/6g/ggen.c
@@ -1292,10 +1292,8 @@ slicearray:
        if(smallintconst(&nodes[2]) && smallintconst(&nodes[4])) {
                v = mpgetfix(nodes[2].val.u.xval) *
                        mpgetfix(nodes[4].val.u.xval);
-               if(v != 0) {
-                       nodconst(&n1, types[tptr], v);
-                       gins(optoas(OADD, types[tptr]), &n1, &nodes[0]);
-               }
+               if(v != 0)
+                       ginscon(optoas(OADD, types[tptr]), v, &nodes[0]);
        } else {
                regalloc(&n1, types[tptr], &nodes[2]);
                gmove(&nodes[2], &n1);
@@ -1409,10 +1407,8 @@ sliceslice:
                gins(optoas(OAS, types[tptr]), &n2, &n1);
                v = mpgetfix(nodes[1].val.u.xval) *
                        mpgetfix(nodes[3].val.u.xval);
-               if(v != 0) {
-                       nodconst(&n2, types[tptr], v);
-                       gins(optoas(OADD, types[tptr]), &n2, &n1);
-               }
+               if(v != 0)
+                       ginscon(optoas(OADD, types[tptr]), v, &n1);
        } else {
                gmove(&nodes[1], &n1);
                if(!smallintconst(&nodes[3]) || mpgetfix(nodes[3].val.u.xval) != 1)

diff --git a/src/cmd/6g/gsubr.c b/src/cmd/6g/gsubr.c
index abece5e50cb2dd20e01700e6b6994c0d7127b1ba..1cd5c650bd4555c23fc620e3aa47b3b4a4382d33 100644 (file)
--- a/src/cmd/6g/gsubr.c
+++ b/src/cmd/6g/gsubr.c
@@ -430,11 +430,33 @@ fatal("shouldnt be used");
 void
 gconreg(int as, vlong c, int reg)
 {
-       Node n1, n2;
+       Node nr;
+
+       nodreg(&nr, types[TINT64], reg);
+       ginscon(as, c, &nr);
+}
+
+/*
+ * generate
+ *     as $c, n
+ */
+void
+ginscon(int as, vlong c, Node *n2)
+{
+       Node n1, ntmp;
 
        nodconst(&n1, types[TINT64], c);
-       nodreg(&n2, types[TINT64], reg);
-       gins(as, &n1, &n2);
+
+       if(as != AMOVQ && (c < -1LL<<31 || c >= 1LL<<31)) {
+               // cannot have 64-bit immediokate in ADD, etc.
+               // instead, MOV into register first.
+               regalloc(&ntmp, types[TINT64], N);
+               gins(AMOVQ, &n1, &ntmp);
+               gins(as, &ntmp, n2);
+               regfree(&ntmp);
+               return;
+       }
+       gins(as, &n1, n2);
 }
 
 #define        CASE(a,b)       (((a)<<16)|((b)<<0))