Skip to content

Updates to RISC-V compiler selection (prefer gcc-riscv32-pico-elf and maximum -march opts) #2921

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
kilograham wants to merge 4 commits into
base: develop
Choose a base branch
from
Open

Updates to RISC-V compiler selection (prefer gcc-riscv32-pico-elf and maximum -march opts) #2921

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
11179ac
Make gcc-riscv32-pico-elf the preferred compiler, and add support for…
kilograham May 1, 2026
3281ce4
Apply suggestions from code review
kilograham May 7, 2026
52cc707
Add '-mcpu=hazard3-rp2350' as a RISC-V compile flags option (preferred)
kilograham May 7, 2026
b5568ba
use empty.c for risc-v compiler check
kilograham May 7, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
9 changes: 6 additions & 3 deletions cmake/preload/toolchains/pico_riscv_gcc.cmake
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,7 +1,10 @@
set(CMAKE_SYSTEM_PROCESSOR hazard3)

set(PICO_DEFAULT_GCC_TRIPLE riscv32-unknown-elf riscv32-corev-elf riscv-none-elf)

set(PICO_COMMON_LANG_FLAGS " -march=rv32imac_zicsr_zifencei_zba_zbb_zbs_zbkb -mabi=ilp32")
set(PICO_DEFAULT_GCC_TRIPLE riscv32-pico-elf riscv32-unknown-elf riscv32-corev-elf riscv-none-elf)

# ordered list of preferred flags to support
set(PICO_COMMON_LANG_FLAGS_LIST
" -mcpu=hazard3-rp2350"
" -march=rv32ima_zicsr_zifencei_zba_zbb_zbs_zbkb_zca_zcb_zcmp -mabi=ilp32"
" -march=rv32imac_zicsr_zifencei_zba_zbb_zbs_zbkb -mabi=ilp32")
include(${CMAKE_CURRENT_LIST_DIR}/util/pico_riscv_gcc_common.cmake)
2 changes: 1 addition & 1 deletion cmake/preload/toolchains/pico_riscv_gcc_zcb_zcmp.cmake
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@

set(CMAKE_SYSTEM_PROCESSOR hazard3)

set(PICO_DEFAULT_GCC_TRIPLE riscv32-unknown-elf riscv32-corev-elf riscv-none-elf)
set(PICO_DEFAULT_GCC_TRIPLE riscv32-pico-elf riscv32-unknown-elf riscv32-corev-elf riscv-none-elf)

set(PICO_COMMON_LANG_FLAGS " -march=rv32ima_zicsr_zifencei_zba_zbb_zbs_zbkb_zca_zcb_zcmp -mabi=ilp32")

Expand Down
Empty file added cmake/preload/toolchains/util/empty.c
View file
Open in desktop
Empty file.
37 changes: 37 additions & 0 deletions cmake/preload/toolchains/util/find_compiler.cmake
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -39,3 +39,40 @@ function(pico_find_compiler_with_triples compiler_path triples compiler_suffix)
pico_find_compiler(${compiler_path} "${triples}")
set(${compiler_path} ${${compiler_path}} PARENT_SCOPE)
endfunction()

# If no single compiler flags variable is set, then choose first working compiler flags from a list.
# This is done by doing a test compile via execute_process, as we can't use check_c_compiler_flag
# prior to project_setup.
# Assuming the single flag variable is not already set, each of the flag_var_list flags are tried in order.
# If the flags don't cause an error the single flag variable is set to the good flag value. If no valid flags
# are found, a fatal error is raised.
function(pico_choose_compiler_flags compiler_path common_lang_flags_var common_lang_flags_var_list)
# simplify logic by not complaining if both set, since CMake calls compiler setup repeatedly
if (NOT ${common_lang_flags_var})
if (${common_lang_flags_var_list})
if(CMAKE_HOST_WIN32)
set(NULL_DEVICE "NUL")
else()
set(NULL_DEVICE "/dev/null")
endif()
foreach(flags IN LISTS ${common_lang_flags_var_list})
separate_arguments(COMPILER_CMD NATIVE_COMMAND "${compiler_path} ${flags} -x c -c ${CMAKE_CURRENT_LIST_DIR}/empty.c -o ${NULL_DEVICE}")
Copy link
Copy Markdown
Contributor

@will-v-pi will-v-pi May 8, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

The path needs quoting as it may contain spaces, which then throws the error:

riscv32-unknown-elf-gcc.exe: fatal error: cannot specify '-o' with '-c', '-S' or '-E' with multiple files
Suggested change
separate_arguments(COMPILER_CMD NATIVE_COMMAND "${compiler_path} ${flags} -x c -c ${CMAKE_CURRENT_LIST_DIR}/empty.c -o ${NULL_DEVICE}")
separate_arguments(COMPILER_CMD NATIVE_COMMAND "${compiler_path} ${flags} -x c -c \"${CMAKE_CURRENT_LIST_DIR}/empty.c\" -o ${NULL_DEVICE}")

execute_process(
COMMAND ${COMPILER_CMD}
RESULT_VARIABLE COMPILE_FAILED
ERROR_QUIET
)

if (NOT COMPILE_FAILED)
set(${common_lang_flags_var} ${flags} PARENT_SCOPE)
return()
endif()
endforeach()
message(FATAL_ERROR "No compiler found that supports required compiler flags")
else()
if (${common_lang_flags_var_list})
message(FATAL_ERROR "Either ${common_lang_flags_var} or ${common_lang_flags_var_list} must be set")
endif()
endif()
endif()
endfunction()
3 changes: 2 additions & 1 deletion cmake/preload/toolchains/util/pico_gcc_common.cmake
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@ include(${CMAKE_CURRENT_LIST_DIR}/find_compiler.cmake)
# include our Platform/PICO.cmake
set(CMAKE_SYSTEM_NAME PICO)

# PICO_CMAKE_CONFIG: PICO_GCC_TRIPLE, List of GCC_TRIPLES -- usually only one -- to try when searching for a compiler. This may be specified as an environment variable, type=string, default=PICO_DEFAULT_GCC_TRIPLE which is set based on PICO_COMPILER, group=pico_base, docref=cmake-toolchain-config
# PICO_CMAKE_CONFIG: PICO_GCC_TRIPLE, List of GCC_TRIPLES -- usually only one -- to try when searching for a compiler. This may be specified as an environment variable, type=string, default=PICO_DEFAULT_GCC_TRIPLE which is set based on PICO_COMPILER, group=pico_base, docref=cmake-toolchain-config
if (NOT PICO_GCC_TRIPLE)
if (DEFINED ENV{_SAVED_PICO_GCC_TRIPLE})
# saved within the same cmake invocation
Expand All @@ -23,6 +23,7 @@ set(ENV{_SAVED_PICO_GCC_TRIPLE} "${PICO_GCC_TRIPLE}")

# Find GCC
pico_find_compiler_with_triples(PICO_COMPILER_CC "${PICO_GCC_TRIPLE}" gcc)
pico_choose_compiler_flags(${PICO_COMPILER_CC} PICO_COMMON_LANG_FLAGS PICO_COMMON_LANG_FLAGS_LIST)
pico_find_compiler_with_triples(PICO_COMPILER_CXX "${PICO_GCC_TRIPLE}" g++)
set(PICO_COMPILER_ASM "${PICO_COMPILER_CC}" CACHE INTERNAL "")
pico_find_compiler_with_triples(PICO_OBJCOPY "${PICO_GCC_TRIPLE}" objcopy)
Expand Down
4 changes: 4 additions & 0 deletions cmake/preload/toolchains/util/set_flags.cmake
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,10 @@ option(PICO_DEOPTIMIZED_DEBUG "Build debug builds with -O0" 0)
# PICO_CMAKE_CONFIG: PICO_DEBUG_INFO_IN_RELEASE, Include debug information in release builds, type=bool, default=1, group=build, docref=cmake-toolchain-config
option(PICO_DEBUG_INFO_IN_RELEASE "Include debug info in release builds" 1)

if (NOT PICO_COMMON_LANG_FLAGS)
message(FATAL_ERROR "PICO_COMMON_LANG_FLAGS not set")
endif()

get_property(IS_IN_TRY_COMPILE GLOBAL PROPERTY IN_TRY_COMPILE)
foreach(LANG IN ITEMS C CXX ASM)
set(CMAKE_${LANG}_FLAGS_INIT "${PICO_COMMON_LANG_FLAGS}")
Expand Down
Loading