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From b0f9ac365f91952f6f920c8e6aa4ddb819f47cc8 Mon Sep 17 00:00:00 2001
From: Keith Packard <keithp@keithp.com>
Date: Tue, 23 Aug 2022 22:13:08 -0700
Subject: [PATCH] picolibc: Add custom spec file fragments for using
picolibc
The '--oslib=' option allows targets to insert an OS library after the
C library in the LIB_PATH spec file fragment. This library maps a few
POSIX APIs used by picolibc to underlying system capabilities.
The '--crt0=' option allows targets to use an alternate crt0 in place
of the usual one as provided by Picolibc.
For example, picolibc provides 'libsemihost' and 'crt0-semihost.o' on
various targets which maps some POSIX APIs to semihosting capabilities
and signals the semihosting environment when 'main' returns. These
would be used by specifying --oslib=semihost --crt0=semihost.
This patch also takes advantage of the IN_GPP conditional when
building g++ to elide exception handling contents from the executable
when not linking with the g++ driver.
Signed-off-by: Keith Packard <keithp@keithp.com>
---
gcc/config.gcc | 7 +++++++
gcc/config/picolibc.h | 44 ++++++++++++++++++++++++++++++++++++++++++++
gcc/config/picolibc.opt | 33 +++++++++++++++++++++++++++++++++
3 files changed, 84 insertions(+)
create mode 100644 gcc/config/picolibc.h
create mode 100644 gcc/config/picolibc.opt
--- a/gcc/config.gcc
+++ b/gcc/config.gcc
@@ -5931,3 +5931,10 @@
tm_defines="$tm_defines DEFAULT_LIBC=$default_libc"
;;
esac
+
+case "$default_libc" in
+ LIBC_PICOLIBC)
+ extra_options="${extra_options} picolibc.opt"
+ tm_file="${tm_file} picolibc.h"
+ ;;
+esac
--- /dev/null
+++ b/gcc/config/picolibc.h
@@ -0,0 +1,44 @@
+/* Configuration common to all targets running Picolibc.
+ Copyright (C) 2023 Free Software Foundation, Inc.
+
+ This file is part of GCC.
+
+ GCC is free software; you can redistribute it and/or modify it
+ under the terms of the GNU General Public License as published
+ by the Free Software Foundation; either version 3, or (at your
+ option) any later version.
+
+ GCC 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.
+
+ Under Section 7 of GPL version 3, you are granted additional
+ permissions described in the GCC Runtime Library Exception, version
+ 3.1, as published by the Free Software Foundation.
+
+ You should have received a copy of the GNU General Public License and
+ a copy of the GCC Runtime Library Exception along with this program;
+ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
+ <http://www.gnu.org/licenses/>. */
+
+#ifdef IN_GPP
+#define PICOLIBC_LD "picolibcpp.ld"
+#define PICOLIBC_BEGIN " crtbegin%O%s"
+#define PICOLIBC_END "crtend%O%s"
+#else
+#define PICOLIBC_LD "picolibc.ld"
+#define PICOLIBC_BEGIN ""
+#define PICOLIBC_END ""
+#endif
+
+#undef LIB_SPEC
+#define LIB_SPEC "%{!T:-T" PICOLIBC_LD "} --start-group -lc %{-oslib=*:-l%*} %(libgcc) --end-group"
+
+#undef STARTFILE_SPEC
+#define STARTFILE_SPEC "%{-crt0=*:crt0-%*%O%s; :crt0%O%s}" PICOLIBC_BEGIN
+
+#undef ENDFILE_SPEC
+#define ENDFILE_SPEC PICOLIBC_END
+
+#define EH_TABLES_CAN_BE_READ_ONLY 1
--- /dev/null
+++ b/gcc/config/picolibc.opt
@@ -0,0 +1,33 @@
+; Processor-independent options for picolibc.
+;
+; Copyright (C) 2022 Free Software Foundation, Inc.
+;
+; This file is part of GCC.
+;
+; GCC is free software; you can redistribute it and/or modify it under
+; the terms of the GNU General Public License as published by the Free
+; Software Foundation; either version 3, or (at your option) any later
+; version.
+;
+; GCC 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 a copy of the GNU General Public License
+; along with GCC; see the file COPYING3. If not see
+; <http://www.gnu.org/licenses/>.
+
+-oslib
+Driver Separate Alias(-oslib=)
+
+-oslib=
+Driver Joined
+Specify an OS support library to load after libc.
+
+-crt0
+Driver Separate Alias(-crt0=)
+
+-crt0=
+Driver Joined
+Specify an alternate startup file.
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