Add first party C tests

Add first party C tests that can be used for tests specific to this model. This uses Clang as the cross-compiler.

This includes a copy of `nanoprinf` for printing to the UART.

CMakeLists.txt

@@ -117,8 +117,8 @@ add_subdirectory("model")
 # Emulator binary.
 add_subdirectory("c_emulator")
 
-# Old pre-compiled riscv-tests.
-add_subdirectory("test/riscv-tests")
+# Old pre-compiled riscv-tests & first-party tests.
+add_subdirectory("test")
 
 # Release packaging.
 if (NOT CPACK_GENERATOR)

test/CMakeLists.txt

@@ -0,0 +1,2 @@
+add_subdirectory("riscv-tests")
+add_subdirectory("first_party")

test/README.md

@@ -0,0 +1,4 @@
+# Tests
+
+* `riscv-tests` - a collection of very old pre-compiled ELFs from [the `riscv-tests` repo](https://github.com/riscv-software-src/riscv-tests). These are bare minimum tests; not very exhaustive at all.
+* `first_party` - tests specifically designed for this Sail model. These tests are not designed to test all the features of RISC-V. Rather they are for testing new code that we add, and bug fixes.

test/first_party/CMakeLists.txt

@@ -0,0 +1,101 @@
+
+# First party tests
+
+# TODO: Probably make these optional and off by default, but enabled in CI.
+# Then it doesn't trip up people who just want the model, but it's also
+# not too annoying for contributors.
+
+find_program(CLANG_BIN "clang")
+if (NOT CLANG_BIN)
+    message(FATAL_ERROR "clang not found. This is required to compile the first-party tests. You can download it from https://github.com/llvm/llvm-project/releases")
+endif()
+message(STATUS "Found clang: ${CLANG_BIN}")
+
+# Check it supports RISC-V. It is apparently possible to compile Clang without
+# RISC-V support. For example the version Red Hat provides on RHEL 8 doesn't support it.
+execute_process(
+    COMMAND clang -print-targets
+    OUTPUT_VARIABLE clang_targets
+    COMMAND_ERROR_IS_FATAL ANY
+)
+
+# Check if `riscv32` is present in the output
+if (NOT clang_targets MATCHES "riscv32")
+    message(FATAL_ERROR "Your Clang compiler does not support RISC-V (see '${CLANG_BIN} -print-targets'). Please download one from https://github.com/llvm/llvm-project/releases")
+endif()
+
+set(common_deps
+    "src/common/crt0.S"
+    "src/common/encoding.h"
+    "src/common/link.ld"
+    "src/common/nanoprintf.c"
+    "src/common/nanoprintf.h"
+    "src/common/riscv_int.h"
+    "src/common/runtime.c"
+    "src/common/runtime.h"
+)
+
+set(tests
+    "test_hello_world.c"
+    "test_max_pmp.c"
+    "test_minstret.S"
+)
+
+foreach (xlen IN ITEMS 32 64)
+    foreach (test_source IN LISTS tests)
+        set(arch "rv${xlen}d")
+        if (xlen EQUAL 32)
+            set(mabi "ilp32")
+        else()
+            set(mabi "lp64")
+        endif()
+
+        set(elf "${arch}_${test_source}.elf")
+
+        add_custom_command(
+            OUTPUT ${elf}
+            DEPENDS ${common_deps} "src/${test_source}"
+            COMMAND ${CLANG_BIN}
+                --target=riscv${xlen}
+                # The ISA string to compile for.
+                -march=rv${xlen}gc
+                # Calling convention to use. Valid values are 'ilp32' or 'lp64' for 32/64-bit,
+                # optionally followed by 'f' or 'd' for hard-float. All combinations are valid.
+                -mabi=${mabi}d
+                # Indicate we are building in a standalone environment. Implies -fno-builtin
+                # so the compiler won't assume that memcpy etc. are available.
+                -ffreestanding
+                # Don't try to link with libc or libc.
+                -nostdlib
+                # Generate a statically linked binary.
+                -static
+                # The relocation model. This compiles the code so that it can
+                # be linked at any address. This means the linker script
+                # doesn't have to e.g. put all code in the first 2GB of memory.
+                -mcmodel=medany
+                # Generate debug info.
+                -g
+                # Optimise code generation for a good debugging experience.
+                -Og
+                # Enable warnings and upgrade them to errors.
+                -Wall
+                -Werror
+                # The linker script.
+                -T "${CMAKE_CURRENT_SOURCE_DIR}/src/common/link.ld"
+                -o ${elf}
+                "${CMAKE_CURRENT_SOURCE_DIR}/src/${test_source}"
+                "${CMAKE_CURRENT_SOURCE_DIR}/src/common/crt0.S"
+                "${CMAKE_CURRENT_SOURCE_DIR}/src/common/nanoprintf.c"
+                "${CMAKE_CURRENT_SOURCE_DIR}/src/common/runtime.c"
+            VERBATIM
+            COMMENT "Compiling ${test_source}"
+        )
+
+        add_custom_target(build_${arch}_${test_source} ALL DEPENDS ${elf})
+
+        add_test(
+            NAME "first_party_${arch}_${test_source}"
+            COMMAND $<TARGET_FILE:riscv_sim_${arch}> --pmp-count 16 ${elf}
+        )
+    endforeach()
+endforeach()