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-rw-r--r--backends/riscv_retval.c251
1 files changed, 251 insertions, 0 deletions
diff --git a/backends/riscv_retval.c b/backends/riscv_retval.c
new file mode 100644
index 00000000..35b6010b
--- /dev/null
+++ b/backends/riscv_retval.c
@@ -0,0 +1,251 @@
+/* Function return value location for Linux/RISC-V ABI.
+ Copyright (C) 2018 Sifive, Inc.
+ Copyright (C) 2013 Red Hat, Inc.
+ 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 riscv_
+#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_lp64 (const Dwarf_Op **locp, Dwarf_Word size)
+{
+ static const Dwarf_Op loc[] =
+ {
+ { .atom = DW_OP_reg10 }, { .atom = DW_OP_piece, .number = 8 },
+ { .atom = DW_OP_reg11 }, { .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_breg10 } };
+
+ *locp = loc;
+ return 1;
+}
+
+static int
+pass_in_fpr_lp64f (const Dwarf_Op **locp, Dwarf_Word size)
+{
+ static const Dwarf_Op loc[] =
+ {
+ { .atom = DW_OP_regx, .number = 42 },
+ { .atom = DW_OP_piece, .number = 4 },
+ { .atom = DW_OP_regx, .number = 43 },
+ { .atom = DW_OP_piece, .number = 4 }
+ };
+
+ *locp = loc;
+ return size <= 4 ? 1 : 4;
+}
+
+static int
+pass_in_fpr_lp64d (const Dwarf_Op **locp, Dwarf_Word size)
+{
+ static const Dwarf_Op loc[] =
+ {
+ { .atom = DW_OP_regx, .number = 42 },
+ { .atom = DW_OP_piece, .number = 8 },
+ { .atom = DW_OP_regx, .number = 43 },
+ { .atom = DW_OP_piece, .number = 8 }
+ };
+
+ *locp = loc;
+ return size <= 8 ? 1 : 4;
+}
+
+static int
+flatten_aggregate_arg (Dwarf_Die *typedie __attribute__ ((unused)),
+ Dwarf_Die *arg0 __attribute__ ((unused)),
+ Dwarf_Die *arg1 __attribute__ ((unused)))
+{
+ /* ??? */
+ return 1;
+}
+
+static int
+pass_by_flattened_arg (const Dwarf_Op **locp __attribute__ ((unused)),
+ Dwarf_Word size __attribute__ ((unused)),
+ Dwarf_Die *arg0 __attribute__ ((unused)),
+ Dwarf_Die *arg1 __attribute__ ((unused)))
+{
+ /* ??? */
+ return -2;
+}
+
+int
+riscv_return_value_location_lp64d (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)
+ {
+ Dwarf_Die arg0, arg1;
+
+ if (dwarf_aggregate_size (&typedie, &size) < 0)
+ return -1;
+ /* A struct containing just one floating-point real is passed as though
+ it were a standalone floating-point real. A struct containing two
+ floating-point reals is passed in two floating-point registers, if
+ neither is more than FLEN bits wide. A struct containing just one
+ complex floating-point number is passed as though it were a struct
+ containing two floating-point reals. A struct containing one
+ floating-point real and one integer (or bitfield), in either order,
+ is passed in a floating-point register and an integer register,
+ provided the floating-point real is no more than FLEN bits wide and
+ the integer is no more than XLEN bits wide. */
+ if (tag == DW_TAG_structure_type
+ && flatten_aggregate_arg (&typedie, &arg0, &arg1))
+ return pass_by_flattened_arg (locp, size, &arg0, &arg1);
+ /* Aggregates larger than 2*XLEN bits are passed by reference. */
+ else if (size > 16)
+ return pass_by_ref (locp);
+ /* Aggregates whose total size is no more than XLEN bits are passed in
+ a register. Aggregates whose total size is no more than 2*XLEN bits
+ are passed in a pair of registers. */
+ else
+ return pass_in_gpr_lp64 (locp, size);
+ }
+
+ if (tag == DW_TAG_base_type
+ || tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type)
+ {
+ if (dwarf_bytesize_aux (&typedie, &size) < 0)
+ {
+ if (tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type)
+ 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 XLEN bits wide are passed in a single
+ argument register. Scalars that are 2*XLEN bits wide are
+ passed in a pair of argument registers. Scalars wider than
+ 2*XLEN are passed by reference; there are none for LP64D. */
+ return pass_in_gpr_lp64 (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_lp64d (locp, size);
+
+ case 16: /* quad */
+ return pass_in_gpr_lp64 (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 */
+ return pass_in_fpr_lp64f (locp, size);
+
+ case 16: /* double _Complex */
+ return pass_in_fpr_lp64d (locp, size);
+
+ case 32: /* long double _Complex */
+ return pass_by_ref (locp);
+
+ default:
+ return -2;
+ }
+ }
+
+ return -2;
+ }
+ else
+ return pass_in_gpr_lp64 (locp, size);
+ }
+
+ *locp = NULL;
+ return 0;
+}
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