On 01/09/15 04:32, Robert Suchanek wrote:
Hi Steven/Vladimir,
It's hard to say what the correct fix should be, but it sounds like
the address you get after the substitutions should be simplified
(folded).
Coming back to the original testcase and re-analyzing the problem, it appears
that there is, indeed, a missing case for simplification of LO_SUM/HIGH pair.
The patch attached resolves the issue.
Although the testcase is not reproducible on the trunk, I think it is still
worth to include it in case the ICE reoccurred.
The patch has been bootstrapped and regtested on x86_64-unknown-linux-gnu target
and similarly tested against SVN revision r212763 where it can be reproduced.
Regards,
Robert
2015-01-08 Robert Suchanek <robert.sucha...@imgtec.com>
gcc/
* simplify-rtx.c (simplify_replace_fn_rtx): Simplify (lo_sum (high x)
(const (plus x offset))) to (const (plus x offset)).
You have to be careful here. Whether or not this transformation is
valid depends on the size of the offset and whether or not the port has
an overlap between its sethi and losum insns and whether or not any
rounding occurs when applying the relocations for sethi/losum as well as
potentially other factors.
We don't currently have a way for ports to indicate what offsets would
make this kind of simplification valid. In fact, there's at least one
port (PA) where the validity of this kind of simplification can't be
determined until after LRA/reload when you know the full context of how
the result is going to be used.
Jeff
