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Re: Help restricting args of an intrinsic function
- From: Diego Novillo <dnovillo at redhat dot com>
- To: Mike Stump <mrs at apple dot com>
- Cc: Syd Polk <spolk at apple dot com>, GCC List <gcc at gcc dot gnu dot org>
- Date: Fri, 30 Jan 2004 23:29:42 -0500
- Subject: Re: Help restricting args of an intrinsic function
- Organization: Red Hat Canada
- References: <E1368D70-53A1-11D8-9B07-003065BDF310@apple.com>
On Fri, 2004-01-30 at 22:59, Mike Stump wrote:
> On Friday, January 30, 2004, at 05:38 PM, Diego Novillo wrote:
> > Yes, that's fine. Here's what tree-ssa emits after the tree
> > optimization passes for the test cases you mentioned.
> So, does your scheme work when the optimizer is off (-O0)?
Of course not. Syd's problem can only be addressed if you have some
minimal data flow information available. If the other compilers claim
that they can get the convoluted cases with the optimizers turned off,
they are lying.
But you bring up a good point. One of the ideas that are floating about
is to enable a minimal amount of optimization even at -O0. Enabling
CFG, SSA and, say, DCE and the dominator optimizers would probably be a
You don't even need to do this analysis on trees. If the tree
optimizers emit the call with the constants propagated, you just have to
match it in your RTL patterns.