LoongArch ELF ABI specification - Return values:
https://loongson.github.io/LoongArch-Documentation/LoongArch-ELF-ABI-EN.html#_return_values
Signed-off-by: Liwei Ge <geli...@openanolis.org>
Signed-off-by: Youling Tang <tangyoul...@loongson.cn>
---
backends/ChangeLog | 6 ++
backends/Makefile.am | 2 +-
backends/loongarch_init.c | 3 +
backends/loongarch_retval.c | 202 ++++++++++++++++++++++++++++++++++++
4 files changed, 212 insertions(+), 1 deletion(-)
create mode 100644 backends/loongarch_retval.c
diff --git a/backends/ChangeLog b/backends/ChangeLog
index 85abc8a5..40564ca7 100644
--- a/backends/ChangeLog
+++ b/backends/ChangeLog
@@ -1,3 +1,9 @@
+2023-04-07 Youling Tang <tangyoul...@loongson.cn>
+
+ * Makefile.am (loongarch_SRCS): Add loongarch_retval.c.
+ * loongarch_init.c (loongarch_init): Hook return_value_location.
+ * loongarch_retval.c: New file.
+
2023-04-07 Youling Tang <tangyoul...@loongson.cn>
* Makefile.am (loongarch_SRCS): Add loongarch_initreg.c.
diff --git a/backends/Makefile.am b/backends/Makefile.am
index e7055d7e..9277ed59 100644
--- a/backends/Makefile.am
+++ b/backends/Makefile.am
@@ -97,7 +97,7 @@ csky_SRCS = csky_attrs.c csky_init.c csky_symbol.c csky_cfi.c
\
csky_regs.c csky_initreg.c csky_corenote.c
loongarch_SRCS = loongarch_init.c loongarch_symbol.c loongarch_cfi.c \
- loongarch_regs.c loongarch_initreg.c
+ loongarch_regs.c loongarch_initreg.c loongarch_retval.c
arc_SRCS = arc_init.c arc_symbol.c
diff --git a/backends/loongarch_init.c b/backends/loongarch_init.c
index 9c4b94a0..8892a2e6 100644
--- a/backends/loongarch_init.c
+++ b/backends/loongarch_init.c
@@ -1,5 +1,7 @@
/* Initialization of LoongArch specific backend library.
Copyright (C) 2022 Hengqi Chen
+ Copyright (C) 2023 OpenAnolis community LoongArch SIG.
+ Copyright (C) 2023 Loongson Technology Corporation Limted.
This file is part of elfutils.
This file is free software; you can redistribute it and/or modify
@@ -52,6 +54,7 @@ loongarch_init (Elf *elf __attribute__ ((unused)),
eh->frame_nregs = 74;
HOOK (eh, check_special_symbol);
HOOK (eh, set_initial_registers_tid);
+ HOOK (eh, return_value_location);
return eh;
}
diff --git a/backends/loongarch_retval.c b/backends/loongarch_retval.c
new file mode 100644
index 00000000..23b33ed5
--- /dev/null
+++ b/backends/loongarch_retval.c
@@ -0,0 +1,202 @@
+/* Function return value location for Linux/LoongArch ABI.
+ Copyright (C) 2013 Red Hat, Inc.
+ Copyright (C) 2023 OpenAnolis community LoongArch SIG.
+ Copyright (C) 2023 Loongson Technology Corporation Limited.
+
+ This file is part of elfutils.
+
+ This file is free software; you can redistribute it and/or modify
+ it under the terms of either
+
+ * the GNU Lesser General Public License as published by the Free
+ Software Foundation; either version 3 of the License, or (at
+ your option) any later version
+
+ or
+
+ * the GNU General Public License as published by the Free
+ Software Foundation; either version 2 of the License, or (at
+ your option) any later version
+
+ or both in parallel, as here.
+
+ elfutils is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ General Public License for more details.
+
+ You should have received copies of the GNU General Public License and
+ the GNU Lesser General Public License along with this program. If
+ not, see <http://www.gnu.org/licenses/>. */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <stdio.h>
+#include <inttypes.h>
+
+#include <assert.h>
+#include <dwarf.h>
+
+#define BACKEND loongarch_
+#include "libebl_CPU.h"
+
+static int
+dwarf_bytesize_aux (Dwarf_Die *die, Dwarf_Word *sizep)
+{
+ int bits;
+ if (((bits = 8 * dwarf_bytesize (die)) < 0
+ && (bits = dwarf_bitsize (die)) < 0)
+ || bits % 8 != 0)
+ return -1;
+
+ *sizep = bits / 8;
+ return 0;
+}
+
+static int
+pass_in_gpr (const Dwarf_Op **locp, Dwarf_Word size)
+{
+ static const Dwarf_Op loc[] =
+ {
+ { .atom = DW_OP_reg4 }, { .atom = DW_OP_piece, .number = 8 },
+ { .atom = DW_OP_reg5 }, { .atom = DW_OP_piece, .number = 8 }
+ };
+
+ *locp = loc;
+ return size <= 8 ? 1 : 4;
+}
+
+static int
+pass_by_ref (const Dwarf_Op **locp)
+{
+ static const Dwarf_Op loc[] = { { .atom = DW_OP_breg4 } };
+
+ *locp = loc;
+ return 1;
+}
+
+static int
+pass_in_fpr (const Dwarf_Op **locp, Dwarf_Word size)
+{
+ static const Dwarf_Op loc[] =
+ {
+ { .atom = DW_OP_regx, .number = 32 },
+ { .atom = DW_OP_piece, .number = 8 },
+ { .atom = DW_OP_regx, .number = 33 },
+ { .atom = DW_OP_piece, .number = 8 }
+ };
+
+ *locp = loc;
+ return size <= 8 ? 1 : 4;
+}
+
+int
+loongarch_return_value_location(Dwarf_Die *functypedie,
+ const Dwarf_Op **locp)
+{
+ /* Start with the function's type, and get the DW_AT_type attribute,
+ which is the type of the return value. */
+ Dwarf_Die typedie;
+ int tag = dwarf_peeled_die_type (functypedie, &typedie);
+ if (tag <= 0)
+ return tag;
+
+ Dwarf_Word size = (Dwarf_Word)-1;
+
+ /* If the argument type is a Composite Type that is larger than 16
+ bytes, then the argument is copied to memory allocated by the
+ caller and the argument is replaced by a pointer to the copy. */
+ if (tag == DW_TAG_structure_type || tag == DW_TAG_union_type
+ || tag == DW_TAG_class_type || tag == DW_TAG_array_type)
+ {
+ if (dwarf_aggregate_size (&typedie, &size) < 0)
+ return -1;
+
+ /* Aggregates larger than 2*GRLEN bits are passed by reference. */
+ if (size > 16)
+ return pass_by_ref (locp);
+ /* Aggregates whose total size is no more than GRLEN bits are passed in
+ a register. Aggregates whose total size is no more than 2*GRLEN bits
+ are passed in a pair of registers. */
+ else
+ return pass_in_gpr (locp, size);
+ }
+
+ if (tag == DW_TAG_base_type || dwarf_is_pointer (tag))
+ {
+ if (dwarf_bytesize_aux (&typedie, &size) < 0)
+ {
+ if (dwarf_is_pointer (tag))
+ size = 8;
+ else
+ return -1;
+ }
+
+ Dwarf_Attribute attr_mem;
+ if (tag == DW_TAG_base_type)
+ {
+ Dwarf_Word encoding;
+ if (dwarf_formudata (dwarf_attr_integrate (&typedie, DW_AT_encoding,
+ &attr_mem),
+ &encoding) != 0)
+ return -1;
+
+ switch (encoding)
+ {
+ case DW_ATE_boolean:
+ case DW_ATE_signed:
+ case DW_ATE_unsigned:
+ case DW_ATE_unsigned_char:
+ case DW_ATE_signed_char:
+ /* Scalars that are at most GRLEN bits wide are passed in a single
+ argument register. Scalars that are 2*GRLEN bits wide are
+ passed in a pair of argument registers. Scalars wider than
+ 2*GRLEN are passed by reference. */
+ return pass_in_gpr (locp, size);
+
+ case DW_ATE_float:
+ /* A real floating-point argument is passed in a floating-point
+ argument register if it is no more than FLEN bits wide,
+ otherwise it is passed according to the integer calling
+ convention. */
+ switch (size)
+ {
+ case 4: /* single */
+ case 8: /* double */
+ return pass_in_fpr (locp, size);
+
+ case 16: /* quad */
+ return pass_in_gpr (locp, size);
+
+ default:
+ return -2;
+ }
+
+ case DW_ATE_complex_float:
+ /* A complex floating-point number is passed as though it were a
+ struct containing two floating-point reals. */
+ switch (size)
+ {
+ case 8: /* float _Complex */
+ case 16: /* double _Complex */
+ return pass_in_fpr (locp, size);
+
+ case 32: /* long double _Complex */
+ return pass_by_ref (locp);
+
+ default:
+ return -2;
+ }
+ }
+
+ return -2;
+ }
+ else
+ return pass_in_gpr (locp, size);
+ }
+
+ *locp = NULL;
+ return 0;
+}
--
2.37.1
