The Go language spec clarified that a lookup on nil map should work and
return a zero value. This patch to the Go frontend and the Go library
implements that. Bootstrapped and ran Go testsuite on
x86_64-unknown-linux-gnu. Committed to mainline. (This patch requires
rebuilding the entire Go library, as the signature of one of the runtime
support functions changed.)
Ian
diff -r 72af58e2d1a6 go/runtime.def
--- a/go/runtime.def Tue Sep 20 17:55:35 2011 -0700
+++ b/go/runtime.def Wed Sep 21 10:25:43 2011 -0700
@@ -87,8 +87,8 @@
R1(POINTER))
// Look up a key in a map returning whether it is present.
-DEF_GO_RUNTIME(MAPACCESS2, "runtime.mapaccess2", P3(MAP, POINTER, POINTER),
- R1(BOOL))
+DEF_GO_RUNTIME(MAPACCESS2, "runtime.mapaccess2",
+ P4(TYPE, MAP, POINTER, POINTER), R1(BOOL))
// Tuple assignment to a map element.
DEF_GO_RUNTIME(MAPASSIGN2, "runtime.mapassign2",
diff -r 72af58e2d1a6 go/statements.cc
--- a/go/statements.cc Tue Sep 20 17:55:35 2011 -0700
+++ b/go/statements.cc Wed Sep 21 10:25:43 2011 -0700
@@ -1085,14 +1085,16 @@
Statement::make_temporary(Type::lookup_bool_type(), NULL, loc);
b->add_statement(present_temp);
- // present_temp = mapaccess2(MAP, &key_temp, &val_temp)
+ // present_temp = mapaccess2(DESCRIPTOR, MAP, &key_temp, &val_temp)
+ Expression* a1 = Expression::make_type_descriptor(map_type, loc);
+ Expression* a2 = map_index->map();
Temporary_reference_expression* ref =
Expression::make_temporary_reference(key_temp, loc);
- Expression* a1 = Expression::make_unary(OPERATOR_AND, ref, loc);
+ Expression* a3 = Expression::make_unary(OPERATOR_AND, ref, loc);
ref = Expression::make_temporary_reference(val_temp, loc);
- Expression* a2 = Expression::make_unary(OPERATOR_AND, ref, loc);
- Expression* call = Runtime::make_call(Runtime::MAPACCESS2, loc, 3,
- map_index->map(), a1, a2);
+ Expression* a4 = Expression::make_unary(OPERATOR_AND, ref, loc);
+ Expression* call = Runtime::make_call(Runtime::MAPACCESS2, loc, 4,
+ a1, a2, a3, a4);
ref = Expression::make_temporary_reference(present_temp, loc);
ref->set_is_lvalue();
diff -r 72af58e2d1a6 libgo/runtime/go-map-delete.c
--- a/libgo/runtime/go-map-delete.c Tue Sep 20 17:55:35 2011 -0700
+++ b/libgo/runtime/go-map-delete.c Wed Sep 21 10:25:43 2011 -0700
@@ -9,6 +9,7 @@
#include "go-alloc.h"
#include "go-assert.h"
+#include "go-panic.h"
#include "map.h"
/* Delete the entry matching KEY from MAP. */
@@ -25,6 +26,9 @@
size_t bucket_index;
void **pentry;
+ if (map == NULL)
+ __go_panic_msg ("assignment to entry in nil map");
+
descriptor = map->__descriptor;
key_descriptor = descriptor->__map_descriptor->__key_type;
diff -r 72af58e2d1a6 libgo/runtime/go-map-index.c
--- a/libgo/runtime/go-map-index.c Tue Sep 20 17:55:35 2011 -0700
+++ b/libgo/runtime/go-map-index.c Wed Sep 21 10:25:43 2011 -0700
@@ -9,6 +9,7 @@
#include "go-alloc.h"
#include "go-assert.h"
+#include "go-panic.h"
#include "map.h"
/* Rehash MAP to a larger size. */
@@ -85,6 +86,13 @@
size_t bucket_index;
char *entry;
+ if (map == NULL)
+ {
+ if (insert)
+ __go_panic_msg ("assignment to entry in nil map");
+ return NULL;
+ }
+
descriptor = map->__descriptor;
key_descriptor = descriptor->__map_descriptor->__key_type;
diff -r 72af58e2d1a6 libgo/runtime/map.goc
--- a/libgo/runtime/map.goc Tue Sep 20 17:55:35 2011 -0700
+++ b/libgo/runtime/map.goc Wed Sep 21 10:25:43 2011 -0700
@@ -9,17 +9,18 @@
typedef unsigned char byte;
typedef _Bool bool;
-typedef struct __go_map hmap;
+typedef struct __go_map_type MapType;
+typedef struct __go_map Hmap;
typedef struct __go_hash_iter hiter;
/* Access a value in a map, returning a value and a presence indicator. */
-func mapaccess2(h *hmap, key *byte, val *byte) (present bool) {
+func mapaccess2(t *MapType, h *Hmap, key *byte, val *byte) (present bool) {
byte *mapval;
size_t valsize;
mapval = __go_map_index(h, key, 0);
- valsize = h->__descriptor->__map_descriptor->__val_type->__size;
+ valsize = t->__val_type->__size;
if (mapval == nil) {
__builtin_memset(val, 0, valsize);
present = 0;
@@ -31,7 +32,7 @@
/* Optionally assign a value to a map (m[k] = v, p). */
-func mapassign2(h *hmap, key *byte, val *byte, p bool) {
+func mapassign2(h *Hmap, key *byte, val *byte, p bool) {
if (!p) {
__go_map_delete(h, key);
} else {
@@ -46,7 +47,7 @@
/* Initialize a range over a map. */
-func mapiterinit(h *hmap, it *hiter) {
+func mapiterinit(h *Hmap, it *hiter) {
__go_mapiterinit(h, it);
}
