23.x: [cpullvm] Add picolibc v1.8.12 overlay

.github/workflows/linux-premerge.yml

@@ -39,6 +39,14 @@ jobs:
             target_os: Linux-x86_64
             runner: cpullvm-ubuntu24-x86_64
 
+          # FIXME: this should maybe go into the nightly instead,
+          # but I don't want to keep triggering those until we're
+          # closer to being ready to merge.
+          - build_script: build_picolibc-v1812_overlay.sh
+            test_script: test_picolibc-v1812_overlay.sh
+            target_os: Linux-x86_64
+            runner: cpullvm-ubuntu24-x86_64
+
     steps:
       - name: Checkout source
         uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1

qualcomm-software/CMakeLists.txt

@@ -120,7 +120,7 @@ set(LLVM_TOOLCHAIN_C_LIBRARY
     "Which C library to use."
 )
 set_property(CACHE LLVM_TOOLCHAIN_C_LIBRARY
-    PROPERTY STRINGS picolibc musl-embedded)
+    PROPERTY STRINGS picolibc picolibc-v1812 musl-embedded)
 
 option(
     SHORT_BUILD_PATHS
@@ -819,9 +819,12 @@ install(
     COMPONENT llvm-toolchain-docs
 )
 
-if(LLVM_TOOLCHAIN_C_LIBRARY MATCHES "^picolibc")
+if(LLVM_TOOLCHAIN_C_LIBRARY STREQUAL picolibc)
     string(APPEND LIBC_LICENSE_FILES " - Picolibc: third-party-licenses/COPYING.NEWLIB, third-party-licenses/COPYING.picolibc\n")
 endif()
+if(LLVM_TOOLCHAIN_C_LIBRARY STREQUAL picolibc-v1812)
+    string(APPEND LIBC_LICENSE_FILES " - Picolibc: third-party-licenses/COPYING.picolibc\n")
+endif()
 if(LLVM_TOOLCHAIN_C_LIBRARY STREQUAL musl-embedded OR ENABLE_LINUX_LIBRARIES)
     string(APPEND LIBC_LICENSE_FILES " - musl-embedded: third-party-licenses/musl-embedded-COPYRIGHT.txt\n")
     if(ENABLE_LINUX_LIBRARIES)
@@ -867,9 +870,14 @@ list(APPEND third_party_license_files
 
 if(LLVM_TOOLCHAIN_C_LIBRARY MATCHES "^picolibc")
     list(APPEND third_party_license_files
-        ${${LLVM_TOOLCHAIN_C_LIBRARY}_SOURCE_DIR}/COPYING.NEWLIB           COPYING.NEWLIB
-        ${${LLVM_TOOLCHAIN_C_LIBRARY}_SOURCE_DIR}/COPYING.picolibc         COPYING.picolibc
+        ${${LLVM_TOOLCHAIN_C_LIBRARY}_SOURCE_DIR}/COPYING.picolibc COPYING.picolibc
     )
+    # COPYING.NEWLIB has been removed in picolibc 1.8.11 and later.
+    if(LLVM_TOOLCHAIN_C_LIBRARY STREQUAL "picolibc")
+        list(APPEND third_party_license_files
+            ${${LLVM_TOOLCHAIN_C_LIBRARY}_SOURCE_DIR}/COPYING.NEWLIB COPYING.NEWLIB
+        )
+    endif()
 elseif(LLVM_TOOLCHAIN_C_LIBRARY STREQUAL musl-embedded)
     list(APPEND third_party_license_files
         ${musl-embedded_SOURCE_DIR}/COPYRIGHT musl-embedded-COPYRIGHT.txt

qualcomm-software/embedded-multilib/CMakeLists.txt

@@ -27,11 +27,11 @@ set(llvmproject_src_dir ${TOOLCHAIN_SOURCE_DIR}/..)
 set(MULTILIB_JSON "" CACHE STRING "JSON file to load library definitions from.")
 set(ENABLE_VARIANTS "all" CACHE STRING "Semicolon separated list of variants to build, or \"all\". Must match entries in the json.")
 set(C_LIBRARY "picolibc" CACHE STRING "Which C library to use.")
-set_property(CACHE C_LIBRARY PROPERTY STRINGS picolibc musl-embedded)
+set_property(CACHE C_LIBRARY PROPERTY STRINGS picolibc picolibc-v1812 musl-embedded)
 
 # multilib.json and the per-variant JSON files only know about one
 # "picolibc" entry, shared by every fetched picolibc version (e.g.
-# picolibc-main), not a separate entry per version. So map C_LIBRARY to
+# picolibc-v1812), not a separate entry per version. So map C_LIBRARY to
 # its base library name before looking anything up there.
 if(C_LIBRARY MATCHES "^picolibc")
     set(json_library_key picolibc)

qualcomm-software/embedded-runtimes/CMakeLists.txt

@@ -25,7 +25,7 @@ set(llvmproject_src_dir ${TOOLCHAIN_SOURCE_DIR}/..)
 # CMake arguments are loaded from the JSON file depending on which C
 # library is used, so this must be set before the JSON is processed.
 set(C_LIBRARY "picolibc" CACHE STRING "Which C library to use.")
-set_property(CACHE C_LIBRARY PROPERTY STRINGS picolibc musl-embedded)
+set_property(CACHE C_LIBRARY PROPERTY STRINGS picolibc picolibc-v1812 musl-embedded)
 
 set(VARIANT_JSON "" CACHE STRING "JSON file to load args from.")
 if(VARIANT_JSON)

qualcomm-software/embedded-runtimes/meson-cross-build.txt.in

@@ -6,12 +6,9 @@ cpp_ld = 'eld'
 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
-# setting stdin to /dev/null prevents qemu from fiddling with the echo bit of
-# the parent terminal
 exe_wrapper = [
-    'sh',
-    '-c',
-    'test -z "$PICOLIBC_TEST" || @Python3_EXECUTABLE@ @picolibc_test_executor_bin@ "$@" < /dev/null',
+    'env',
+    '@Python3_EXECUTABLE@',
     '@picolibc_test_executor_bin@',
     @meson_test_executor_params@]
 

qualcomm-software/embedded-runtimes/test-support/picolibc-test-wrapper.py

@@ -11,13 +11,19 @@
 from run_qemu import run_qemu
 import argparse
 import pathlib
+import subprocess
 import sys
 
 
-def run(args):
+def run(args, extra_args):
     # Some picolibc tests expect argv[0] to be literally "program-name", not
     # the actual program name.
-    argv = ["program-name"] + args.arguments
+    argv = ["program-name"] + extra_args
+    if args.args:
+        # In picolibc v1.8.11 and later, arguments from the picolibc tests
+        # will come as a string rather than a list, so append to the first
+        # element and let the semihosting library handle the splitting.
+        argv[0] += " " + args.args
     if args.qemu_command:
         return run_qemu(
             args.qemu_command,
@@ -30,6 +36,11 @@ def run(args):
             pathlib.Path.cwd(),
             args.verbose,
             args.trace,
+            # Setting stdin to /dev/null prevents qemu from fiddling with
+            # the echo bit of the parent terminal when meson runs multiple
+            # tests in parallel. stdin is only tested by picolibc when
+            # test-stdin=true, which is not the default.
+            stdin=subprocess.DEVNULL,
         )
 
 
@@ -62,18 +73,21 @@ def main():
         help="Print verbose output. This may affect test result, as the output "
         "will be added to the output of the test.",
     )
-    parser.add_argument("image", help="image file to execute")
     parser.add_argument(
-        "arguments",
-        nargs=argparse.REMAINDER,
-        default=[],
-        help="optional arguments for the image",
+        "--args",
+        help="String containing optional arguments for the image",
     )
-    args = parser.parse_args()
+    parser.add_argument("image", help="image file to execute")
+    # FIXME: We need to support picolibc versions both with and without
+    # https://github.com/picolibc/picolibc/commit/295b45098fb189185c973376b53d48b86b65e4ae.
+    # Once all supported picolibc versions have this commit (picolibc v1.8.11
+    # or later), `extra_args` should be removed and this can go back to just
+    # `parse_args()`.
+    args, extra_args = parser.parse_known_args()
     # --qemu-cpu is encoded with colons instead of commas to survive CMake list
     # separator substitution (LIST_SEPARATOR ,).  Decode it back here.
     args.qemu_cpu = args.qemu_cpu.replace(":", ",") if args.qemu_cpu else None
-    ret_code = run(args)
+    ret_code = run(args, extra_args)
     sys.exit(ret_code)
 
 

qualcomm-software/embedded-runtimes/test-support/run_qemu.py

@@ -27,6 +27,7 @@ def run_qemu(
     working_directory,
     verbose,
     trace,
+    stdin=None,
 ):
     """Execute the program using QEMU and return the subprocess return code."""
     qemu_params = ["-M", qemu_machine]
@@ -73,6 +74,7 @@ def run_qemu(
 
     result = subprocess.run(
         command,
+        stdin=stdin,
         stdout=subprocess.PIPE,
         stderr=sys.stderr,
         timeout=timeout,

qualcomm-software/embedded-runtimes/test-support/xfails.py

@@ -96,6 +96,20 @@ def check_r52_warning():
         p = subprocess.run(test_args, capture_output=True, check=False)
         return p.returncode != 0
 
+    # FIXME: Eventualy it might make more sense to add a `libc` member into
+    # `XFail` for more direct use depending on how many libc-specific xfails
+    # are needed. But, while supporting multiple picolibc versions is new,
+    # using the existing conditionals seems an unobtrusive and flexible way
+    # forward.
+    # Test whether picolibc is cpullvm's v1.8.12 version.
+    def check_picolibc_is_v1812():
+        return args.libc == 'picolibc-v1812'
+
+    # Test whether picolibc is cpullvm's "primary" version (currently between
+    # v1.8.10 and v1.8.11).
+    def check_picolibc_is_primary():
+        return args.libc == 'picolibc'
+
     xfails = [
         XFail(
             name="no frwpi",
@@ -175,6 +189,24 @@ def check_r52_warning():
             ],
             description="Disable the tests for now while the issue is being fixed upstream (https://github.com/picolibc/picolibc/pull/1072).",
         ),
+        XFail(
+            name="picolibc v1.8.12 hello-raw",
+            testnames=[
+                "test-hello-raw.test",
+                "test-hello-raw-no-flash.test",
+            ],
+            result=NewResult.EXCLUDE,
+            conditional=check_picolibc_is_v1812,
+            project="picolibc",
+            variants=[
+                "aarch64a_tlsie",
+                "aarch64a_soft_nofp_tlsie",
+            ],
+            description="picolibc's `*-raw-*` tests rely on serial port usage "
+                        "to exit correctly which our existing wrappers are not "
+                        "setup to handle. Exclude them for now as we aren't losing "
+                        "any significant test coverage by doing so.",
+        ),
         XFail(
             name="Insufficient RAM",
             testnames=[
@@ -290,8 +322,10 @@ def check_r52_warning():
                 "std/language.support/support.start.term/quick_exit.pass.cpp",
             ],
             result=NewResult.XFAILED,
+            conditional=check_picolibc_is_primary,
             project="libcxx",
-            description="at_quick_exit symbol is not found in the picolibc semihosting runtime.",
+            description="quick_exit, at_quick_exit, and __cxa_at_quick_exit were first added "
+                        "in picolibc v1.8.12. Older versions fail with undefined symbols.",
         ),
         XFail(
             name="uchar-cuchar-xpass-picolibc",

qualcomm-software/patches/picolibc-v1812/0001-Enable-libcxx-builds.patch

@@ -0,0 +1,52 @@
+From a59afdaf3697da7a1cfc62e0f957be780d6ae11a Mon Sep 17 00:00:00 2001
+From: Simi Pallipurath <simi.pallipurath@arm.com>
+Date: Thu, 14 Nov 2024 10:07:08 +0000
+Subject: Enable libcxx builds
+
+Modifications to build config and linker script required to enable
+libc++ builds.
+---
+ meson.build    | 12 ++++++++++++
+ picolibc.ld.in |  3 +++
+ 2 files changed, 15 insertions(+)
+
+diff --git a/meson.build b/meson.build
+index f33d011b2..2c653de02 100644
+--- a/meson.build
++++ b/meson.build
+@@ -1340,6 +1340,18 @@ NEWLIB_MAJOR_VERSION=4
+ NEWLIB_MINOR_VERSION=3
+ NEWLIB_PATCHLEVEL_VERSION=0
+
++conf_data.set('_GNU_SOURCE', '',
++        description: '''Enable GNU functions like strtof_l.
++It's necessary to set this globally because inline functions in
++libc++ headers call the GNU functions.'''
++)
++
++conf_data.set('_PICOLIBC_CTYPE_SMALL', '0',
++        description: '''Disable picolibc's small ctype implementation.
++libc++ expects newlib-style ctype tables, and also expects support for locales
++and extended character sets, so picolibc's small ctype is not compatible with it'''
++)
++
+ conf_data.set('__HAVE_CC_INHIBIT_LOOP_TO_LIBCALL',
+ 	      cc.has_argument('-fno-tree-loop-distribute-patterns'),
+ 	      description: 'Compiler flag to prevent detecting memcpy/memset patterns')
+diff --git a/picolibc.ld.in b/picolibc.ld.in
+index 0bcfe4ca8..c3055c49e 100644
+--- a/picolibc.ld.in
++++ b/picolibc.ld.in
+@@ -69,6 +69,9 @@ SECTIONS
+ 		*(.literal.startup .text.startup .literal.startup.* .text.startup.*)
+ 		*(SORT(.text.sorted.*))
+ 		*(.literal .text .literal.* .text.* .opd .opd.* .branch_lt .branch_lt.* @EXTRA_TEXT_SECTIONS@)
++		PROVIDE (__start___lcxx_override = .);
++		*(__lcxx_override)
++		PROVIDE (__stop___lcxx_override = .);
+ 		*(.gnu.linkonce.t.*)
+ 		KEEP (*(.fini .fini.*))
+ 		@PREFIX@__text_end = .;
+-- 
+2.43.0
+