gcc/
PR debug/111735
* btfout.cc (btf_fwd_to_enum_p): New.
(btf_asm_type_ref): Special case references to enum forwards.
(btf_asm_type): Special case enum forwards. Rename btf_size_type to
btf_size, and change chained ifs switching on btf_kind into else ifs.
gcc/testsuite/
PR debug/111735
* gcc.dg/debug/btf/btf-forward-2.c: New test.
---
gcc/btfout.cc | 46 ++++++++++++++-----
.../gcc.dg/debug/btf/btf-forward-2.c | 18 ++++++++
2 files changed, 53 insertions(+), 11 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/debug/btf/btf-forward-2.c
diff --git a/gcc/btfout.cc b/gcc/btfout.cc
index db4f1084f85..3ec938874b6 100644
--- a/gcc/btfout.cc
+++ b/gcc/btfout.cc
@@ -268,6 +268,17 @@ btf_emit_id_p (ctf_id_t id)
&& (btf_id_map[id] <= BTF_MAX_TYPE));
}
+/* Return true if DTD is a forward-declared enum. The BTF representation
+ of forward declared enums is not formally defined. */
+
+static bool
+btf_fwd_to_enum_p (ctf_dtdef_ref dtd)
+{
+ uint32_t btf_kind = get_btf_kind (CTF_V2_INFO_KIND
(dtd->dtd_data.ctti_info));
+
+ return (btf_kind == BTF_KIND_FWD && dtd->dtd_data.ctti_type == CTF_K_ENUM);
+}
+
/* Each BTF type can be followed additional, variable-length information
completing the description of the type. Calculate the number of bytes
of variable information required to encode a given type. */
@@ -753,8 +764,12 @@ btf_asm_type_ref (const char *prefix, ctf_container_ref
ctfc, ctf_id_t ref_id)
uint32_t ref_kind
= get_btf_kind (CTF_V2_INFO_KIND (ref_type->dtd_data.ctti_info));
+ const char *kind_name = btf_fwd_to_enum_p (ref_type)
+ ? btf_kind_name (BTF_KIND_ENUM)
+ : btf_kind_name (ref_kind);
+
dw2_asm_output_data (4, ref_id, "%s: (BTF_KIND_%s '%s')",
- prefix, btf_kind_name (ref_kind),
+ prefix, kind_name,
get_btf_type_name (ref_type));
}
}
@@ -765,11 +780,11 @@ btf_asm_type_ref (const char *prefix, ctf_container_ref
ctfc, ctf_id_t ref_id)
static void
btf_asm_type (ctf_container_ref ctfc, ctf_dtdef_ref dtd)
{
- uint32_t btf_kind, btf_kflag, btf_vlen, btf_size_type;
+ uint32_t btf_kind, btf_kflag, btf_vlen, btf_size;
uint32_t ctf_info = dtd->dtd_data.ctti_info;
btf_kind = get_btf_kind (CTF_V2_INFO_KIND (ctf_info));
- btf_size_type = dtd->dtd_data.ctti_type;
+ btf_size = dtd->dtd_data.ctti_size;
btf_vlen = CTF_V2_INFO_VLEN (ctf_info);
/* By now any unrepresentable types have been removed. */
@@ -777,7 +792,7 @@ btf_asm_type (ctf_container_ref ctfc, ctf_dtdef_ref dtd)
/* Size 0 integers are redundant definitions of void. None should remain
in the types list by this point. */
- gcc_assert (btf_kind != BTF_KIND_INT || btf_size_type >= 1);
+ gcc_assert (btf_kind != BTF_KIND_INT || btf_size >= 1);
/* Re-encode the ctti_info to BTF. */
/* kflag is 1 for structs/unions with a bitfield member.
@@ -810,16 +825,26 @@ btf_asm_type (ctf_container_ref ctfc, ctf_dtdef_ref dtd)
structs and forwards to unions. The dwarf2ctf conversion process stores
the kind of the forward in ctti_type, but for BTF this must be 0 for
forwards, with only the KIND_FLAG to distinguish.
- At time of writing, BTF forwards to enums are unspecified. */
- if (btf_kind == BTF_KIND_FWD)
+ Forwards to enum types are special-cased below. */
+ else if (btf_kind == BTF_KIND_FWD)
{
if (dtd->dtd_data.ctti_type == CTF_K_UNION)
btf_kflag = 1;
- btf_size_type = 0;
+ /* PR debug/111735. Encode foward-declared enums as BTF_KIND_ENUM
+ with vlen=0. A representation for these is not formally defined;
+ this is the de-facto standard used by other tools like clang
+ and pahole. */
+ else if (dtd->dtd_data.ctti_type == CTF_K_ENUM)
+ {
+ btf_kind = BTF_KIND_ENUM;
+ btf_vlen = 0;
+ }
+
+ btf_size = 0;
}
- if (btf_kind == BTF_KIND_ENUM)
+ else if (btf_kind == BTF_KIND_ENUM)
{
btf_kflag = dtd->dtd_enum_unsigned
? BTF_KF_ENUM_UNSIGNED
@@ -829,7 +854,7 @@ btf_asm_type (ctf_container_ref ctfc, ctf_dtdef_ref dtd)
}
/* PR debug/112656. BTF_KIND_FUNC_PROTO is always anonymous. */
- if (btf_kind == BTF_KIND_FUNC_PROTO)
+ else if (btf_kind == BTF_KIND_FUNC_PROTO)
dtd->dtd_data.ctti_name = 0;
dw2_asm_output_data (4, dtd->dtd_data.ctti_name,
@@ -848,8 +873,7 @@ btf_asm_type (ctf_container_ref ctfc, ctf_dtdef_ref dtd)
case BTF_KIND_ENUM:
case BTF_KIND_DATASEC:
case BTF_KIND_ENUM64:
- dw2_asm_output_data (4, dtd->dtd_data.ctti_size, "btt_size: %uB",
- dtd->dtd_data.ctti_size);
+ dw2_asm_output_data (4, btf_size, "btt_size: %uB", btf_size);
return;
case BTF_KIND_ARRAY:
case BTF_KIND_FWD:
diff --git a/gcc/testsuite/gcc.dg/debug/btf/btf-forward-2.c
b/gcc/testsuite/gcc.dg/debug/btf/btf-forward-2.c
new file mode 100644
index 00000000000..318c4220ec3
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/debug/btf/btf-forward-2.c
@@ -0,0 +1,18 @@
+/* PR111735. Test BTF generation for forward-declared enum.
+
+ The BTF representation for forward-declared enums is not formally
+ defined, but the de-facto representation used by various tools is
+ to encode them as a BTF_KIND_ENUM type with vlen=0 and size=0. */
+
+/* { dg-do compile } */
+/* { dg-options "-O0 -gbtf -dA" } */
+
+enum Foo;
+enum Foo *pfoo;
+
+/* Check that there is one BTF_KIND_ENUM with vlen=0, and no BTF_KIND_FWD. */
+/* { dg-final { scan-assembler-times "\[\t \]0x6000000\[\t
\]+\[^\n\]*btt_info" 1 } } */
+/* { dg-final { scan-assembler-times "\[\t \]0x7000000\[\t
\]+\[^\n\]*btt_info" 0 } } */
+
+/* Verify the reference to the enum-forward. */
+/* { dg-final { scan-assembler-times "btt_type: \\(BTF_KIND_ENUM 'Foo'\\)" 1 }
} */
