The GCC '-maccumulate-outgoing-args' flag is enabled for most configs, mostly because of issues which are no longer relevant. For most configs, and with most recent versions of GCC, it's no longer needed. Clarify which cases need it, and only enable it for those cases. Also produce a compile-time error for the ftrace graph + mcount + '-Os' case, which will otherwise cause runtime failures. The main benefit of '-maccumulate-outgoing-args' is that it prevents an ugly prologue for functions which have aligned stacks. But removing the option also has some benefits: more readable argument saves, smaller text size, and (presumably) slightly improved performance. Here are the object size savings for 32-bit and 64-bit defconfig kernels: text data bss dec hex filename 10006710 3543328 1773568 15323606 e9d1d6 vmlinux.x86-32.before 9706358 3547424 1773568 15027350 e54c96 vmlinux.x86-32.after text data bss dec hex filename 10652105 4537576 843776 16033457 f4a6b1 vmlinux.x86-64.before 10639629 4537576 843776 16020981 f475f5 vmlinux.x86-64.after That comes out to a 3% text size improvement on x86-32 and a 0.1% text size improvement on x86-64.
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| @@ -148,6 +148,10 @@ cc-fullversion = $(shell $(CONFIG_SHELL) \ · 147 unmodified lines | ||
| 148 | 148 | # Usage: EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1) |
| 149 | 149 | cc-ifversion = $(shell [ $(cc-version) $(1) $(2) ] && echo $(3) || echo $(4)) |
| 150 | 150 | |
| 151 | +# cc-if-fullversion | |
| 152 | +# Usage: EXTRA_CFLAGS += $(call cc-if-fullversion, -lt, 040502, -O1) | |
| 153 | +cc-if-fullversion = $(shell [ $(cc-fullversion) $(1) $(2) ] && echo $(3) || echo $(4)) | |
| 154 | + | |
| 151 | 155 | # cc-ldoption |
| 152 | 156 | # Usage: ldflags += $(call cc-ldoption, -Wl$(comma)--hash-style=both) |
| 153 | 157 | cc-ldoption = $(call try-run,\ |