On 06/01/2015 04:55 AM, Richard Biener wrote:
On Sat, May 30, 2015 at 11:11 AM, Marc Glisse <marc.gli...@inria.fr> wrote:
(only commenting on the technique, not on the transformation itself)

+(simplify
+  (cond @0 (convert @1) INTEGER_CST@2)
+  (if (INTEGRAL_TYPE_P (TREE_TYPE (@1))
+       && COMPARISON_CLASS_P (@0)


If you add COMPARISON_CLASS_P to define_predicates, you could write:
(cond COMPARISON_CLASS_P@0 (convert @1) INTEGER_CST@2)

But that would fail to match on GIMPLE, so I don't like either variant
as Jeffs relies on the awkward fact that on GIMPLE cond expr conditions
are GENERIC and yours wouldn't work.

That said - for this kind of patterns testcases that exercise the patterns
on GIMPLE would be very appreciated.
OK. I'll see if I can build a testcase to exercise this in gimple. If that's not possible would you prefer the pattern be restricted to generic just to be safe?


or maybe use a for loop on comparisons, which would give names to
TREE_OPERAND (@0, *). This should even handle the operand_equal_p
alternative:

(cond (cmp:c@0 @1 @2) (convert @1) INTEGER_CST@2)

Yes, that would be my reference.
OK.  easily done.


+       && int_fits_type_p (@2, TREE_TYPE (@1))
+       && ((operand_equal_p (TREE_OPERAND (@0, 0), @2, 0)
+           && operand_equal_p (TREE_OPERAND (@0, 1), @1, 0))
+          || (operand_equal_p (TREE_OPERAND (@0, 0), @1, 0)
+              && operand_equal_p (TREE_OPERAND (@0, 1), @2, 0))))
+    (with { tree itype = TREE_TYPE (@1); tree otype = TREE_TYPE (@2); }
+      (convert:otype (cond:itype @0 @1 (convert:itype @2))))))


This should be enough, no need to specify the outer type
(convert (cond:itype @0 @1 (convert:itype @2))))))

Yes.

I believe we should not have to write cond:itype here, cond should be made
to use the type of its second argument instead of the first one, by default
(expr::gen_transform already has a few special cases).

Indeed.  Patch welcome (I'd have expected it already works...)
One of them is needed, but I can't recall which :-) I'll pull them to generate the failure I'd run into and simplify appropriately and explain whichever is remaining.

jeff

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