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Re: [PATCH, SH] Add support for inlined builtin-strcmp (2/2)


On Thu, 2013-10-17 at 16:15 +0200, Christian Bruel wrote:
> Hello,
> This patch adds support to inline an optimized version of strcmp when
> not optimizing for size. The generated code makes use of the cmp/str
> instruction to test 4 bytes at a time when correctly aligned.
> note that a new pattern was added to match the cmp/str instruction, but
> no attempt was made to catch it from combine.
> This results in general cycles improvements (against both newlib and
> glibc implementations), one of which is a 10%  cycle improvement for a
> famous strcmp-biased "benchmark" starting with a D.... , but still standard.


> This optimization  can be disabled with -fno-builtin-strcmp.
> No regressions on sh4 in big and little endian, and sh2 (sh3, and sh4a
> are still running for big and little endian for sanity)

I was wondering, in file sh-mem.c, the new function
'sh4_expand_cmpstr' ... why is it SH4-something?  It's a bit confusing,
since cmp/str has been around since ever (i.e. since SH1).  Maybe just
rename it to 'sh_expand_cmpstr' instead?  The function always returns
'true', so maybe just make it return 'void'?

Also, in the expander ...

+  [(set (match_operand:SI 0 "register_operand" "")
+	(compare:SI (match_operand:BLK 1 "memory_operand" "")

... no need to use empty "" constraints.


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