Hello,
if we compare for instance size() and capacity() for a std::vector, we get
this kind of pattern. I started with just nop conversions and got a bit
carried away handling all those cases.
Bootstrap+regtest on x86_64-pc-linux-gnu.
2019-06-11 Marc Glisse <marc.gli...@inria.fr>
gcc/
* match.pd (X/[ex]4<Y/[ex]4): Handle conversions.
gcc/testsuite/
* gcc.dg/tree-ssa/cmpexactdiv-5.c: New file.
--
Marc GlisseIndex: gcc/match.pd
===================================================================
--- gcc/match.pd (revision 272105)
+++ gcc/match.pd (working copy)
@@ -1496,25 +1496,40 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
&& TYPE_UNSIGNED (TREE_TYPE (@0))
&& TYPE_PRECISION (TREE_TYPE (@0)) > 1
&& (wi::to_wide (@2)
== wi::max_value (TYPE_PRECISION (TREE_TYPE (@0)), SIGNED) - 1))
(with { tree stype = signed_type_for (TREE_TYPE (@0)); }
(icmp (convert:stype @0) { build_int_cst (stype, 0); })))))
/* X / 4 < Y / 4 iff X < Y when the division is known to be exact. */
(for cmp (simple_comparison)
(simplify
- (cmp (exact_div @0 INTEGER_CST@2) (exact_div @1 @2))
- (if (wi::gt_p (wi::to_wide (@2), 0, TYPE_SIGN (TREE_TYPE (@2))))
- (cmp @0 @1)
+ (cmp (convert?@3 (exact_div @0 INTEGER_CST@2)) (convert? (exact_div @1 @2)))
+ (if (element_precision (TREE_TYPE (@3)) >= element_precision (TREE_TYPE (@0))
+ && types_match (TREE_TYPE (@0), TREE_TYPE (@1)))
(if (wi::lt_p (wi::to_wide (@2), 0, TYPE_SIGN (TREE_TYPE (@2))))
- (cmp @1 @0)))))
+ (if (!TYPE_UNSIGNED (TREE_TYPE (@3)))
+ (cmp @1 @0)
+ (if (tree_expr_nonzero_p (@0) && tree_expr_nonzero_p (@1))
+ (with
+ {
+ tree utype = unsigned_type_for (TREE_TYPE (@0));
+ }
+ (cmp (convert:utype @1) (convert:utype @0)))))
+ (if (wi::gt_p (wi::to_wide (@2), 1, TYPE_SIGN (TREE_TYPE (@2))))
+ (if (TYPE_UNSIGNED (TREE_TYPE (@0)) || !TYPE_UNSIGNED (TREE_TYPE (@3)))
+ (cmp @0 @1)
+ (with
+ {
+ tree utype = unsigned_type_for (TREE_TYPE (@0));
+ }
+ (cmp (convert:utype @0) (convert:utype @1)))))))))
/* X / C1 op C2 into a simple range test. */
(for cmp (simple_comparison)
(simplify
(cmp (trunc_div:s @0 INTEGER_CST@1) INTEGER_CST@2)
(if (INTEGRAL_TYPE_P (TREE_TYPE (@0))
&& integer_nonzerop (@1)
&& !TREE_OVERFLOW (@1)
&& !TREE_OVERFLOW (@2))
(with { tree lo, hi; bool neg_overflow;
Index: gcc/testsuite/gcc.dg/tree-ssa/cmpexactdiv-5.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/cmpexactdiv-5.c (nonexistent)
+++ gcc/testsuite/gcc.dg/tree-ssa/cmpexactdiv-5.c (working copy)
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-optimized-raw" } */
+
+int f(int *a, int *b, int *c){
+ if(sizeof(__SIZE_TYPE__) != sizeof(__PTRDIFF_TYPE__)) return 2;
+ __SIZE_TYPE__ s = b - a;
+ __SIZE_TYPE__ t = c - a;
+ return s < t;
+}
+
+/* { dg-final { scan-tree-dump-not "exact_div_expr" "optimized" } } */
