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Re: C++ PATCH: improve performance of vbase initialization
- To: Mark Mitchell <mark at codesourcery dot com>
- Subject: Re: C++ PATCH: improve performance of vbase initialization
- From: Richard Henderson <rth at cygnus dot com>
- Date: Sun, 16 Jan 2000 16:13:27 -0800
- Cc: gcc-patches at gcc dot gnu dot org
- References: <20000116122249Y.mitchell@codesourcery.com>
On Sun, Jan 16, 2000 at 12:22:49PM -0800, Mark Mitchell wrote:
> BTW, I'm surprised that GCSE isn't able to eliminate the redundant
> test of edx. Any ideas?
We don't currently do gcse on hard registers. E.g. (reg:CCNO 17 flags).
It hurts the x86 port elsewhere too -- the clobbering of flags by
arithmetic means that gcse is effectively crippled.
It's something that could (perhaps easily) be addressed. The reason we
don't handle hard regs now is that Doug Evans' initial implementation was
on a deadline and didn't want to have to think about any hidden traps.
r~