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Re: [PATCH] New fold_range_test optimizations (take 2)
- From: Roger Sayle <roger at eyesopen dot com>
- To: Jakub Jelinek <jakub at redhat dot com>
- Cc: gcc-patches at gcc dot gnu dot org, Alexandre Oliva <aoliva at redhat dot com>
- Date: Thu, 17 Jun 2004 18:39:36 -0600 (MDT)
- Subject: Re: [PATCH] New fold_range_test optimizations (take 2)
On Thu, 17 Jun 2004, Jakub Jelinek wrote:
> 2004-06-17 Jakub Jelinek <firstname.lastname@example.org>
> * fold-const.c (build_range_check): If !in_p and recursive call
> fails, exit immediately. If high - low overflows and etype is
> a signed type, retry with unsigned etype.
> (merge_ranges): If !in0_p and !in1_p, handle even range2 adjacent
> to range1 at TYPE_MAX_VALUE and TYPE_MIN_VALUE.
> * gcc.dg/range-test-1.c: New test.
This is OK for mainline. If its no trouble, could you add an extra
sentence to the comment above build_range_check mentioning that this
function can return NULL_TREE (all the callers check for a zero result,
but this isn't described in the function's documentation).
Thanks also to Alex for catching the INT_MAX + 1 != INT_MIN issue,
presumably for types narrower than their mode. With those changes
it looks like your use of lang_hooks.types.unsigned_type is safe
even when the C++ front-end returns a "utype" of different width to
the original "etype", such that fold_convert performs an implicit
sign extension, c.f. PR middle-end/15069 and