[ATfE] Add hermetic testing in LLVM-libc (#420)

Adds hermetic test support (`ninja check-llvmlibc`) with ARMv7-M and
ARMv8-M as an experimental feature. This runs the tests provided
upstream by `libc/test`, using their framework. It does not pass every
test, however, it runs all the available tests.

This also rearranges the `samples` to use a new linker script,
`llvmlibc.ld`. This is based on `picolibc.ld`.

Author: saturn691

arm-software/embedded/CMakeLists.txt

@@ -384,7 +384,7 @@ if(LLVM_TOOLCHAIN_C_LIBRARY STREQUAL llvmlibc)
 
     install(
       DIRECTORY
-      ${CMAKE_CURRENT_SOURCE_DIR}/llvmlibc-samples/src
+      ${CMAKE_CURRENT_SOURCE_DIR}/llvmlibc-samples/
       DESTINATION samples
       COMPONENT llvm-toolchain-llvmlibc-configs
     )

arm-software/embedded/arm-multilib/json/variants/armv7m_soft_nofp_exn_rtti_size.json

@@ -32,7 +32,7 @@
         },
         "llvmlibc": {
             "ENABLE_CXX_LIBS": "ON",
-            "ENABLE_LIBC_TESTS": "OFF",
+            "ENABLE_LIBC_TESTS": "ON",
             "ENABLE_COMPILER_RT_TESTS": "OFF",
             "ENABLE_LIBCXX_TESTS": "OFF"
         }

arm-software/embedded/arm-multilib/json/variants/armv8m.main_hard_fp_unaligned_size.json

@@ -32,7 +32,7 @@
         },
         "llvmlibc": {
             "ENABLE_CXX_LIBS": "ON",
-            "ENABLE_LIBC_TESTS": "OFF",
+            "ENABLE_LIBC_TESTS": "ON",
             "ENABLE_COMPILER_RT_TESTS": "OFF",
             "ENABLE_LIBCXX_TESTS": "OFF"
         }

arm-software/embedded/arm-runtimes/CMakeLists.txt

@@ -159,8 +159,10 @@ if(ENABLE_LIBC_TESTS OR ENABLE_COMPILER_RT_TESTS OR ENABLE_LIBCXX_TESTS)
             set(picocrt "crt0-semihost-fvp")
         endif()
         set(test_link_flags "-nostartfiles -l${picocrt} -lsemihost -T picolibcpp.ld")
+    elseif(C_LIBRARY STREQUAL llvmlibc)
+        # QEMU logic handled later
     else()
-        message(FATAL_ERROR "Tests can only be enabled using picolibc.")
+        message(FATAL_ERROR "Tests can only be enabled using picolibc or llvmlibc.")
     endif()
 
     if(TEST_EXECUTOR STREQUAL qemu)
@@ -633,10 +635,10 @@ endif()
 ###############################################################################
 
 if(C_LIBRARY STREQUAL llvmlibc)
-    if(ENABLE_LIBC_TESTS)
-        message(FATAL_ERROR "Tests cannot yet be enabled using llvm libc.")
+    if(NOT(TEST_EXECUTOR STREQUAL qemu))
+        message(FATAL_ERROR "Using LLVM-libc and FVPs together is unsupported")
     endif()
-
+    set(test_cmd "qemu-system-arm -M ${QEMU_MACHINE} -semihosting -nographic -device loader$<COMMA>file=@BINARY@")
     set(lib_compile_flags "${lib_compile_flags} -Wno-error=atomic-alignment")
 
     set(common_llvmlibc_cmake_args
@@ -679,9 +681,11 @@ if(C_LIBRARY STREQUAL llvmlibc)
         -DLLVM_CMAKE_DIR=${LLVM_BINARY_DIR}/lib/cmake/llvm
         -DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=ON
         -DLLVM_ENABLE_RUNTIMES=libc
-        -DLLVM_INCLUDE_TESTS=OFF # llvmlibc's tests require C++, so can't be built until llvmlibc can support libc++
         -DLLVM_LIBC_ALL_HEADERS=ON
         -DLLVM_LIBC_FULL_BUILD=ON
+        -DLIBC_TEST_LINK_OPTIONS_DEFAULT=-nostartfiles,-lcrt0-semihost,-lsemihost,-T,llvmlibc.ld
+        -DLIBC_TEST_CMD=${test_cmd}
+        -DLIBC_TEST_HERMETIC_ONLY=true
         STEP_TARGETS configure build install
         USES_TERMINAL_CONFIGURE TRUE
         USES_TERMINAL_BUILD TRUE
@@ -716,6 +720,13 @@ if(C_LIBRARY STREQUAL llvmlibc)
         CMAKE_ARGS
         ${compiler_launcher_cmake_args}
         ${common_llvmlibc_cmake_args}
+        -DBOOT_FLASH_ADDRESS=${BOOT_FLASH_ADDRESS}
+        -DBOOT_FLASH_SIZE=${BOOT_FLASH_SIZE}
+        -DFLASH_ADDRESS=${FLASH_ADDRESS}
+        -DFLASH_SIZE=${FLASH_SIZE}
+        -DRAM_ADDRESS=${RAM_ADDRESS}
+        -DRAM_SIZE=${RAM_SIZE}
+        -DSTACK_SIZE=${STACK_SIZE}
         STEP_TARGETS build install
         USES_TERMINAL_CONFIGURE TRUE
         USES_TERMINAL_BUILD TRUE
@@ -724,6 +735,33 @@ if(C_LIBRARY STREQUAL llvmlibc)
         LIST_SEPARATOR ,
         CONFIGURE_HANDLED_BY_BUILD TRUE
     )
+
+    if(ENABLE_LIBC_TESTS)
+        add_custom_target(check-llvmlibc)
+        add_dependencies(check-all check-llvmlibc)
+
+        ExternalProject_Add_Step(
+            llvmlibc
+            check
+            COMMAND "${CMAKE_COMMAND}" --build <BINARY_DIR> --target libc-hermetic-tests
+            DEPENDEES install
+            USES_TERMINAL TRUE
+            EXCLUDE_FROM_MAIN TRUE
+            ALWAYS TRUE
+        )
+
+        ExternalProject_Add_StepTargets(llvmlibc check)
+        ExternalProject_Add_StepDependencies(
+            llvmlibc
+            check
+            llvmlibc-build
+            llvmlibc-support-build
+            compiler_rt-install
+            cxxlibs-install
+        )
+        
+        add_dependencies(check-llvmlibc llvmlibc-check)
+    endif()
 endif()
 
 add_dependencies(clib-configure ${C_LIBRARY}-configure)

arm-software/embedded/llvmlibc-samples/ldscripts/llvmlibc-microbit.ld

@@ -0,0 +1,9 @@
+__boot_flash = 0x00000000;  /* fragment of the flash where interrupt vector goes */
+__boot_flash_size = 0x3000; /* length of flash fragment with interrupt vector */
+__flash = 0x00003000;       /* starting address of the remaining flash */
+__flash_size = 0x3d000;     /* length of the remaining flash */
+__ram = 0x20000000;         /* starting address of RAM bank 0 */
+__ram_size = 0x4000;        /* length of RAM bank 0 */
+__stack_size = 512;
+
+INCLUDE llvmlibc.ld

arm-software/embedded/llvmlibc-samples/src/baremetal-semihosting-llvmlibc/Makefile

@@ -10,7 +10,7 @@ include ../../Makefile.conf
 build: hello.elf
 
 hello.elf: *.c
-	$(BIN_PATH)/clang --config=llvmlibc.cfg $(MICROBIT_TARGET) $(CRT_SEMIHOST) -lm -g -fno-exceptions -fno-rtti -T microbit-llvmlibc.ld -o hello.elf $^
+	$(BIN_PATH)/clang --config=llvmlibc.cfg $(MICROBIT_TARGET) $(CRT_SEMIHOST) -lm -g -fno-exceptions -fno-rtti -T ../../ldscripts/llvmlibc-microbit.ld -o hello.elf $^
 
 %.hex: %.elf
 	$(BIN_PATH)/llvm-objcopy -O ihex $< $@

arm-software/embedded/llvmlibc-samples/src/baremetal-semihosting-llvmlibc/make.bat

@@ -40,6 +40,6 @@ if exist hello.hex del /q hello.hex
 @exit /B 1
 
 :build_fn
-%BIN_PATH%\clang.exe --config=llvmlibc.cfg --target=armv6m-none-eabi -mfloat-abi=soft -march=armv6m -mfpu=none -nostartfiles -lcrt0-semihost -lsemihost -fno-exceptions -fno-rtti -g -T microbit-llvmlibc.ld -lm -o hello.elf hello.c
+%BIN_PATH%\clang.exe --config=llvmlibc.cfg --target=armv6m-none-eabi -mfloat-abi=soft -march=armv6m -mfpu=none -nostartfiles -lcrt0-semihost -lsemihost -fno-exceptions -fno-rtti -g -T ..\..\ldscripts\llvmlibc-microbit.ld -lm -o hello.elf hello.c
 %BIN_PATH%\llvm-objcopy.exe -O ihex hello.elf hello.hex
 @exit /B

arm-software/embedded/llvmlibc-samples/src/cpp-baremetal-semihosting-llvmlibc/Makefile

@@ -10,7 +10,7 @@ include ../../Makefile.conf
 build: hello.elf
 
 hello.elf: *.cpp
-	$(BIN_PATH)/clang++ --config=llvmlibc.cfg $(MICROBIT_TARGET) $(CRT_SEMIHOST) -lm -g -T microbit-llvmlibc.ld -o hello.elf $^
+	$(BIN_PATH)/clang++ --config=llvmlibc.cfg $(MICROBIT_TARGET) $(CRT_SEMIHOST) -lm -g -T ../../ldscripts/llvmlibc-microbit.ld -o hello.elf $^
 
 %.hex: %.elf
 	$(BIN_PATH)/llvm-objcopy -O ihex $< $@

arm-software/embedded/llvmlibc-samples/src/cpp-baremetal-semihosting-llvmlibc/make.bat

@@ -40,6 +40,6 @@ if exist hello.hex del /q hello.hex
 @exit /B 1
 
 :build_fn
-%BIN_PATH%\clang++.exe --config=llvmlibc.cfg --target=armv6m-none-eabi -mfloat-abi=soft -march=armv6m -mfpu=none -nostartfiles -lcrt0-semihost -lsemihost -fno-exceptions -fno-rtti -g -T microbit-llvmlibc.ld -lm -o hello.elf hello.cpp
+%BIN_PATH%\clang++.exe --config=llvmlibc.cfg --target=armv6m-none-eabi -mfloat-abi=soft -march=armv6m -mfpu=none -nostartfiles -lcrt0-semihost -lsemihost -fno-exceptions -fno-rtti -g -T ..\..\ldscripts\llvmlibc-microbit.ld -lm -o hello.elf hello.cpp
 %BIN_PATH%\llvm-objcopy.exe -O ihex hello.elf hello.hex
 @exit /B