Saturn builds

cmake/toolchains/saturn.cmake

@@ -48,13 +48,16 @@ set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
 set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
 set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
 
-# SH-2 core flags: big-endian (-mb), SH-2 ISA (-m2), no FPU
-set(_SAT_C_FLAGS "-m2 -mb -fno-builtin -fomit-frame-pointer")
+# SH-2 core flags: big-endian (-mb), SH-2 ISA (-m2), no FPU.
+# -ffunction-sections/-fdata-sections enable --gc-sections to eliminate
+# unreachable code at the function level (e.g. yyjson FILE* API paths).
+set(_SAT_C_FLAGS "-m2 -mb -fno-builtin -fomit-frame-pointer -ffunction-sections -fdata-sections -Os")
 set(CMAKE_C_FLAGS_INIT   "${_SAT_C_FLAGS}")
 
-# Yaul installs yaul.specs to ${YAUL_INSTALL_ROOT}/sh2eb-elf/lib/ and
-# ldscripts/yaul.x to ${YAUL_INSTALL_ROOT}/sh2eb-elf/lib/ldscripts/.
-# GCC searches ${prefix}/${target}/lib/ for specs, so -specs=yaul.specs works
-# without an absolute path once the SDK is installed.
+# Linker flags: gc-sections, no startup/default libs (Yaul provides crt0/init;
+# we supply all needed libraries explicitly).  -nodefaultlibs prevents cmake/gcc
+# from injecting -lc (which does not exist in the Yaul sysroot).
+# --start-group/--end-group are placed in target_link_libraries in
+# targets/saturn.cmake so they actually wrap the archive list.
 set(CMAKE_EXE_LINKER_FLAGS_INIT
-  "-specs=yaul.specs -Wl,--gc-sections -nostartfiles -Wl,--start-group -Wl,--end-group")
+  "-Wl,--gc-sections -nostartfiles -nodefaultlibs")