picolibc: tests with meson

Switch from manually building picolibc tests to bilding and running them
as part of picolibc build. This enables tests, which were not included
in the manual build.

Several fixes were necessary:

1. Add '-nostdlib' to picolibc c_args
This prevents errors like:
  ld.lld: error: unable to find library -lc
in checks for compiler flags support in picolibs build scripts.
Example of failing check:
  has_link_defsym = meson.get_cross_property('has_link_defsym', cc.has_link_argument('-Wl,--defsym=' + global_prefix + '_start=0'))

2. Make picolibc use compiler_rt in place of libgcc.

3. Change machines used with qemu and adjust memory layouts.
Some of picolibc tests need more memory, than previous machines
provided. Example error:
  ld.lld: error: section '.text' will not fit in region 'flash': overflowed by 34504 bytes

4. Postpone building picolibc tests to the test step. compiler_rt
requires picolibc to be installed. picolibc tests require compiler_rt.
The delayed tests enable picolibc to be installed before compiler_rt is built.

cmake/meson-cross-build.txt.in

@@ -1,9 +1,14 @@
 [binaries]
-c = [@meson_c_args@]
+c = [@meson_c_args@, '-nostdlib']
 ar = '@LLVM_BINARY_DIR@/bin/llvm-ar@CMAKE_EXECUTABLE_SUFFIX@'
 strip = '@LLVM_BINARY_DIR@/bin/llvm-strip@CMAKE_EXECUTABLE_SUFFIX@'
 # only needed to run tests
-exe_wrapper = ['sh', '-c', 'test -z "$PICOLIBC_TEST" || run-@cpu_family@ "$@"', 'run-@cpu_family@']
+exe_wrapper = [
+    'sh',
+    '-c',
+    'test -z "$PICOLIBC_TEST" || @CMAKE_CURRENT_SOURCE_DIR@/test-support/run-picolibc-test.py "$@"',
+    '@CMAKE_CURRENT_SOURCE_DIR@/test-support/run-picolibc-test.py',
+    @run_picolibc_test_args@]
 
 [host_machine]
 system = 'none'
@@ -13,3 +18,9 @@ endian = 'little'
 
 [properties]
 skip_sanity_check = true
+libgcc ='-lclang_rt.builtins'
+default_flash_addr = '@default_flash_addr@'
+default_flash_size = '@default_flash_size@'
+default_ram_addr   = '@default_ram_addr@'
+default_ram_size   = '@default_ram_size@'
+default_stack_size = '@default_stack_size@'

test-support/lit-exec-qemu.py

@@ -26,7 +26,11 @@ def run(args):
     image_args = command[1:]
     qemu_params = args.qemu_params.split(':')
     qemu_cmd = ([args.qemu_command] + qemu_params +
-        ['-semihosting', '-nographic', '-kernel', image])
+        ['-semihosting', '-nographic'])
+    if qemu_params.count("virt"):
+        qemu_cmd += ["-kernel", image]
+    else:
+        qemu_cmd += ["-device", f"loader,file={image},cpu-num=0"]
     if image_args:
         image_args_concat = ','.join(['arg=' + arg.replace(',', ',,')
                                       for arg in image_args])

test-support/run-picolibc-test.py

@@ -0,0 +1,88 @@
+#!/usr/bin/env python3
+
+# Copyright (c) 2023, Arm Limited and affiliates.
+
+# This is a wrapper script to run picolibc tests with qemu
+
+import sys
+import argparse
+import subprocess
+
+# This script requires Python 3.6 or later
+assert sys.version_info >= (3, 6)
+
+disabled_tests = [
+    "picolibc_aarch64-build/test/math_errhandling",
+    "picolibc_armv7em_hard_fpv4_sp_d16-build/test/math_errhandling",
+    "picolibc_armv7em_hard_fpv5_d16-build/test/math_errhandling",
+    "picolibc_armv8m.main_hard_fp-build/test/printf_scanf",
+    "picolibc_armv8m.main_hard_fp-build/test/printff_scanff",
+    "picolibc_armv8m.main_hard_fp-build/test/printff-tests",
+    "picolibc_armv8m.main_hard_fp-build/test/math_errhandling",
+    "picolibc_armv8m.main_hard_fp-build/test/rounding-mode",
+    "picolibc_armv8m.main_hard_fp-build/test/long_double",
+    "picolibc_armv8m.main_hard_fp-build/test/rand",
+    "picolibc_armv8m.main_hard_fp-build/test/fenv",
+    "picolibc_armv8m.main_hard_fp-build/test/math-funcs",
+    "picolibc_armv8m.main_hard_fp-build/test/test-strtod",
+    "picolibc_armv8m.main_hard_fp-build/test/test-efcvt",
+    "picolibc_armv8m.main_hard_fp-build/test/complex-funcs",
+    "picolibc_armv8m.main_hard_fp-build/test/semihost/semihost-times",
+    "picolibc_armv8m.main_hard_fp-build/newlib/libm/test/math_test",
+    "picolibc_armv8m.main_hard_fp-build/test/libc-testsuite/sscanf",
+    "picolibc_armv8m.main_hard_fp-build/test/libc-testsuite/strtod",
+    "picolibc_armv8.1m.main_soft_nofp_nomve-build/newlib/libm/test/math_test",
+    "picolibc_armv8.1m.main_hard_fp-build/test/math_errhandling",
+    "picolibc_armv8.1m.main_hard_fp-build/newlib/libm/test/math_test",
+    "picolibc_armv8.1m.main_hard_nofp_mve-build/test/fenv",
+    "picolibc_armv8.1m.main_hard_nofp_mve-build/newlib/libm/test/math_test",
+    "picolibc_armv8.1m.main_hard_nofp_mve-build/test/math_errhandling"
+]
+
+def is_disabled(image):
+    return any([image.endswith(t) for t in disabled_tests])
+
+def run(args):
+    """Execute the program using QEMU and return the subprocess return code."""
+    command = args.command
+    assert command
+    image = command[0]
+    image_args = command[1:]
+    if image_args[0:1] == ['--']:
+        image_args = image_args[1:]
+    if is_disabled(image):
+        return 77
+    semihosting =  ','.join(
+        ["enable=on", "chardev=stdio0"]
+        + ['arg=' + arg.replace(',', ',,') for arg in image_args])
+    qemu_params = args.qemu_params.split(':') + [
+            "-chardev", "stdio,mux=on,id=stdio0",
+            "-semihosting-config", semihosting,
+            "-monitor", "none",
+            "-serial", "none",
+            "-nographic"]
+    if qemu_params.count("virt"):
+        qemu_params += ["-kernel", image]
+    else:
+        qemu_params += ["-device", f"loader,file={image},cpu-num=0"]
+    qemu_cmd = [args.qemu_command] + qemu_params
+    print(f"qemu_cmd : {qemu_cmd}")
+    result = subprocess.run(qemu_cmd, stdout=subprocess.PIPE,
+                            stderr=sys.stderr,
+                            check=False)
+    sys.stdout.buffer.write(result.stdout)
+    return result.returncode
+
+def main():
+    parser = argparse.ArgumentParser(description='Run a single test using qemu')
+    parser.add_argument('--qemu-command', required=True, help='qemu-system-<arch> path')
+    parser.add_argument('--qemu-params', required=True,
+                        help='list of arguments to pass to qemu, separated with ":"')
+    parser.add_argument('command', nargs=argparse.REMAINDER,
+                        help='image file to execute with optional arguments')
+    args = parser.parse_args()
+    ret_code = run(args)
+    sys.exit(ret_code)
+
+if __name__ == '__main__':
+    main()

tests/ldscripts/picolibc_armv4t.ld

@@ -1,6 +1,6 @@
-__flash =      0x00010000;
+__flash =      0x00000000;
 __flash_size = 0x00400000;
-__ram =        0x00500000;
+__ram =        0x20000000;
 __ram_size   = 0x00200000;
 __stack_size = 4k;
 

tests/ldscripts/picolibc_armv5te.ld

@@ -1,6 +1,6 @@
-__flash =      0x00010000;
+__flash =      0x00000000;
 __flash_size = 0x00400000;
-__ram =        0x00500000;
+__ram =        0x20000000;
 __ram_size   = 0x00200000;
 __stack_size = 4k;
 

tests/ldscripts/picolibc_armv8.1m.main_hard_fp.ld

@@ -1,4 +1,7 @@
-__flash_size = 0x00400000; 
+__flash =      0x10000000;
+__flash_size = 0x00200000;
+__ram =        0x60000000;
+__ram_size   = 0x00200000;
 __stack_size = 4k;
 
 INCLUDE picolibcpp.ld

tests/ldscripts/picolibc_armv8.1m.main_hard_nofp_mve.ld

@@ -1,4 +1,7 @@
-__flash_size = 0x00400000;
+__flash =      0x10000000;
+__flash_size = 0x00200000;
+__ram =        0x60000000;
+__ram_size   = 0x00200000;
 __stack_size = 4k;
 
 INCLUDE picolibcpp.ld

tests/ldscripts/picolibc_armv8.1m.main_soft_nofp_nomve.ld

@@ -1,4 +1,7 @@
-__flash_size = 0x00400000; 
+__flash =      0x10000000;
+__flash_size = 0x00200000;
+__ram =        0x60000000;
+__ram_size   = 0x00200000;
 __stack_size = 4k;
 
 INCLUDE picolibcpp.ld

tests/ldscripts/picolibc_armv8m.main_hard_fp.ld

@@ -1,3 +1,7 @@
+__flash =      0x10000000;
+__flash_size = 0x00400000;
+__ram =        0x80000000;
+__ram_size   = 0x01000000;
 __stack_size = 4k;
 
 INCLUDE picolibcpp.ld

tests/ldscripts/picolibc_armv8m.main_soft_nofp.ld

@@ -1,4 +1,7 @@
+__flash =      0x10000000;
 __flash_size = 0x00400000;
+__ram =        0x80000000;
+__ram_size   = 0x01000000;
 __stack_size = 4k;
 
 INCLUDE picolibcpp.ld