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Re: [tree-ssa] Out of SSA status and issues
- From: kenner at vlsi1 dot ultra dot nyu dot edu (Richard Kenner)
- To: matz at suse dot de
- Cc: gcc at gcc dot gnu dot org
- Date: Tue, 13 May 03 09:47:18 EDT
- Subject: Re: [tree-ssa] Out of SSA status and issues
Suppose there is register pressure and we are in the register allocator
and decide that p1 doesn't get a hardreg. If you now don't allow the use
of p1 to be replaced with *p2, you are forced to emit such code:
Of course, but we weren't talking about the register allocator. Instead,
we were talking about a high-level optimization.
The register allocator indeed needs to know what a psuedo corresponds to
so that it can undo the optimization is there aren't enough hard registers.
We do some of this, but not enough.