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Re: [tree-ssa] CCP fixes
- From: law at redhat dot com
- To: Richard Henderson <rth at redhat dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Tue, 18 Feb 2003 18:29:19 -0700
- Subject: Re: [tree-ssa] CCP fixes
- Reply-to: law at redhat dot com
In message <20030219010422.GB2494@redhat.com>, Richard Henderson writes:
>> >In rtl we have (const (plus (symbol_ref) (const_int))) to
>> >record this, but nothing similar in trees.
>> Yup. I'm just not sure this concept is the best thing to re-introduce
>> into the gimple code.
>If we don't, then the rtl optimizers will need to continue to
>be smart enough to reconstruct the bits that we missed at the
>tree level, due to link-time constants not being considered
Note, we still consider these things constant, hell, we can even
use them to derive other constants. What we do not allow is for
these complex constants to be used as operands for unary or binary
>Your comment about NOP and CONVERT exprs leads me to believe
>that something *exactly* like a CONST_EXPR might be the right
>thing. Anything that passes initializer_constant_valid_p
>could be wrapped in this.
Well, we can put it on the TODO list -- however, until this stuff
is implemented, the CCP pass will need my fix.