dwarf_loader: DW_TAG_subroutine_type may have a DW_AT_byte_size
First seen in Go, where DW_TAG_member don't come with a DW_AT_byte_size,
so we need to figure it out from its type using tag__byte_size() in
class_member__cache_byte_size() so either use the DW_AT_byte size that
comes in DW_TAG_subroutine_type or the cu->addr_size to use the pointer
size.
With this we manage to pretty print this Go class:
$ pahole -C runtime._type ../prometheus-uprobes/main
struct runtime._type {
uintptr size; /* 0 8 */
uintptr ptrdata; /* 8 8 */
uint32 hash; /* 16 4 */
runtime.tflag tflag; /* 20 1 */
uint8 align; /* 21 1 */
uint8 fieldAlign; /* 22 1 */
uint8 kind; /* 23 1 */
func(unsafe.Pointer, unsafe.Pointer) bool equal; /* 24 8 */
uint8 * gcdata; /* 32 8 */
runtime.nameOff str; /* 40 4 */
runtime.typeOff ptrToThis; /* 44 4 */
/* size: 48, cachelines: 1, members: 11 */
/* last cacheline: 48 bytes */
};
At some point we should select how to pretty print this, with a Go
formatter and the above C one :-)
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/dwarf_loader.c b/dwarf_loader.c
index 07a74a1..ccf3194 100644
--- a/dwarf_loader.c
+++ b/dwarf_loader.c
@@ -1286,6 +1286,7 @@
assert(tag == DW_TAG_subprogram || tag == DW_TAG_subroutine_type);
#endif
tag__init(&ftype->tag, cu, die);
+ ftype->byte_size = attr_numeric(die, DW_AT_byte_size);
INIT_LIST_HEAD(&ftype->parms);
ftype->nr_parms = 0;
ftype->unspec_parms = 0;
diff --git a/dwarves.c b/dwarves.c
index b43031c..218367b 100644
--- a/dwarves.c
+++ b/dwarves.c
@@ -1136,6 +1136,7 @@
case DW_TAG_reference_type: return cu->addr_size;
case DW_TAG_base_type: return base_type__size(tag);
case DW_TAG_enumeration_type: return tag__type(tag)->size / 8;
+ case DW_TAG_subroutine_type: return tag__ftype(tag)->byte_size ?: cu->addr_size;
}
if (tag->type == 0) { /* struct class: unions, structs */
diff --git a/dwarves.h b/dwarves.h
index f305923..eb1a6df 100644
--- a/dwarves.h
+++ b/dwarves.h
@@ -868,6 +868,7 @@
struct ftype {
struct tag tag;
struct list_head parms;
+ size_t byte_size; // First seen in DW_TAG_subroutine_type in a Go CU
uint16_t nr_parms;
uint8_t unspec_parms:1; /* just one bit is needed */
uint8_t optimized_parms:1;
