--- a/make/common/NativeCompilation.gmk Tue Aug 22 16:20:29 2017 +0200
+++ b/make/common/NativeCompilation.gmk Wed Aug 23 08:55:13 2017 +0200
@@ -932,10 +932,35 @@
endif
endif
+ # Unfortunately the @-file trick does not work reliably when using clang.
+ # Clang does not propagate the @-file parameter to the ld sub process, but
+ # instead puts the full content on the command line. At least the llvm ld
+ # does not even support an @-file.
+ #
+ # When linking a large amount of object files, we risk hitting the limit
+ # of the command line length even on posix systems if the path length of
+ # the output dir is very long due to our use of absolute paths. To
+ # mitigate this, use paths relative to the output dir when linking over
+ # 500 files with clang and the output dir path is deep.
+ ifneq ($$(word 500, $$($1_ALL_OBJS)), )
+ ifeq ($$(TOOLCHAIN_TYPE), clang)
+ # There is no strlen function in make, but checking path depth is a
+ # reasonable approximation.
+ ifneq ($$(word 10, $$(subst /, ,$$(OUTPUT_ROOT))), )
+ $1_LINK_OBJS_RELATIVE := true
+ $1_ALL_OBJS_RELATIVE := $$(patsubst $$(OUTPUT_ROOT)/%, %, $$($1_ALL_OBJS))
+ endif
+ endif
+ endif
+
$$($1_TARGET): $$($1_ALL_OBJS) $$($1_RES) $$($1_REAL_MAPFILE) \
$$($1_VARDEPS_FILE)
ifneq ($$($1_OBJ_FILE_LIST), )
- $$(eval $$(call ListPathsSafely, $1_ALL_OBJS, $$($1_OBJ_FILE_LIST)))
+ ifeq ($$($1_LINK_OBJS_RELATIVE), true)
+ $$(eval $$(call ListPathsSafely, $1_ALL_OBJS_RELATIVE, $$($1_OBJ_FILE_LIST)))
+ else
+ $$(eval $$(call ListPathsSafely, $1_ALL_OBJS, $$($1_OBJ_FILE_LIST)))
+ endif
endif
# Keep as much as possible on one execution line for best performance
# on Windows
@@ -951,6 +976,7 @@
$$($1_STRIP_CMD)
else
$$(call ExecuteWithLog, $$($1_OBJECT_DIR)/$$($1_SAFE_NAME)_link, \
+ $$(if $$($1_LINK_OBJS_RELATIVE), $$(CD) $$(OUTPUT_ROOT) ; ) \
$$($1_LD) $$($1_LDFLAGS) $$($1_EXTRA_LDFLAGS) $$($1_SYSROOT_LDFLAGS) \
$(LD_OUT_OPTION)$$@ $$($1_LD_OBJ_ARG) $$($1_RES) $$($1_LIBS) \
$$($1_EXTRA_LIBS)) ; \