[Bug tree-optimization/60172] [4.9/4.10 Regression] ARM performance regression from trunk@207239

[bpringlemeir at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60172

Bill Pringlemeir <bpringlemeir at gmail dot com> changed:

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--- Comment #22 from Bill Pringlemeir <bpringlemeir at gmail dot com> ---
The good ARM assembler uses the 'mla' instruction which is a 'multiply and
accumulate'.  Since this is not recognized, the multiply result needs a
temporary register to do the add with and I think this cause the extra
registers.  I believe you should look to see why the 'mla' is not matched.  I
don't know if the x86 has an op-code like this.