On Wed, 6 Jun 2018, Jakub Jelinek wrote:
> Hi!
>
> The following testcase shows another case that can be handled easily.
> If rhs2 is defined in a bb dominated by first_bb, we need to be careful
> because we can't rely on value range information of it after we optimize the
> guarding >= 0 check into 1. On the testcase, we have there
> rhs2 = (int) something_N;
> cast where both types are integral with the same precision, so we can in
> this case just check if something_N is defined in some bb not dominated by
> first_bb, or if it is result of & constant, or zero extension etc.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK.
Thanks,
Richard.
> 2018-06-05 Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/69615
> * tree-ssa-reassoc.c (optimize_range_tests_var_bound): If rhs2 is lhs
> of a cast from a same precision integral SSA_NAME in a bb dominated
> by first_bb, retry with rhs2 set to the rhs1 of the cast. Don't emit
> cast to utype if rhs2 has already a compatible type.
>
> * gcc.dg/tree-ssa/pr69615.c: New test.
>
> --- gcc/tree-ssa-reassoc.c.jj 2018-04-27 09:08:57.667850280 +0200
> +++ gcc/tree-ssa-reassoc.c 2018-06-05 17:01:39.028144763 +0200
> @@ -3172,7 +3172,7 @@ optimize_range_tests_var_bound (enum tre
> to (unsigned) k_32 < (unsigned) iftmp.0_44, then we would execute
> those stmts even for negative k_32 and the value ranges would be no
> longer guaranteed and so the optimization would be invalid. */
> - if (opcode == ERROR_MARK)
> + while (opcode == ERROR_MARK)
> {
> gimple *g = SSA_NAME_DEF_STMT (rhs2);
> basic_block bb2 = gimple_bb (g);
> @@ -3182,21 +3182,37 @@ optimize_range_tests_var_bound (enum tre
> {
> /* As an exception, handle a few common cases. */
> if (gimple_assign_cast_p (g)
> - && INTEGRAL_TYPE_P (TREE_TYPE (gimple_assign_rhs1 (g)))
> - && TYPE_UNSIGNED (TREE_TYPE (gimple_assign_rhs1 (g)))
> - && (TYPE_PRECISION (TREE_TYPE (rhs2))
> - > TYPE_PRECISION (TREE_TYPE (gimple_assign_rhs1 (g)))))
> - /* Zero-extension is always ok. */ ;
> + && INTEGRAL_TYPE_P (TREE_TYPE (gimple_assign_rhs1 (g))))
> + {
> + tree op0 = gimple_assign_rhs1 (g);
> + if (TYPE_UNSIGNED (TREE_TYPE (op0))
> + && (TYPE_PRECISION (TREE_TYPE (rhs2))
> + > TYPE_PRECISION (TREE_TYPE (op0))))
> + /* Zero-extension is always ok. */
> + break;
> + else if (TYPE_PRECISION (TREE_TYPE (rhs2))
> + == TYPE_PRECISION (TREE_TYPE (op0))
> + && TREE_CODE (op0) == SSA_NAME)
> + {
> + /* Cast from signed to unsigned or vice versa. Retry
> + with the op0 as new rhs2. */
> + rhs2 = op0;
> + continue;
> + }
> + }
> else if (is_gimple_assign (g)
> && gimple_assign_rhs_code (g) == BIT_AND_EXPR
> && TREE_CODE (gimple_assign_rhs2 (g)) == INTEGER_CST
> && !wi::neg_p (wi::to_wide (gimple_assign_rhs2 (g))))
> /* Masking with INTEGER_CST with MSB clear is always ok
> - too. */ ;
> - else
> - continue;
> + too. */
> + break;
> + rhs2 = NULL_TREE;
> }
> + break;
> }
> + if (rhs2 == NULL_TREE)
> + continue;
>
> wide_int nz = get_nonzero_bits (rhs2);
> if (wi::neg_p (nz))
> @@ -3253,10 +3269,13 @@ optimize_range_tests_var_bound (enum tre
> gimple_set_uid (g, uid);
> rhs1 = gimple_assign_lhs (g);
> gsi_insert_before (&gsi, g, GSI_SAME_STMT);
> - g = gimple_build_assign (make_ssa_name (utype), NOP_EXPR, rhs2);
> - gimple_set_uid (g, uid);
> - rhs2 = gimple_assign_lhs (g);
> - gsi_insert_before (&gsi, g, GSI_SAME_STMT);
> + if (!useless_type_conversion_p (utype, TREE_TYPE (rhs2)))
> + {
> + g = gimple_build_assign (make_ssa_name (utype), NOP_EXPR, rhs2);
> + gimple_set_uid (g, uid);
> + rhs2 = gimple_assign_lhs (g);
> + gsi_insert_before (&gsi, g, GSI_SAME_STMT);
> + }
> if (tree_swap_operands_p (rhs1, rhs2))
> {
> std::swap (rhs1, rhs2);
> --- gcc/testsuite/gcc.dg/tree-ssa/pr69615.c.jj 2018-06-06
> 12:55:16.535159073 +0200
> +++ gcc/testsuite/gcc.dg/tree-ssa/pr69615.c 2018-06-06 12:54:53.993133421
> +0200
> @@ -0,0 +1,16 @@
> +/* PR tree-optimization/69615 */
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> +/* { dg-final { scan-tree-dump-not " >= 0" "optimized" } } */
> +/* { dg-final { scan-tree-dump-not " < 0" "optimized" } } */
> +
> +extern void foo (void);
> +
> +void
> +bar (int z, unsigned int y)
> +{
> + long long x = z;
> + y &= 0xf;
> + if (x >= 0 && x < (int) y)
> + foo ();
> +}
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB
21284 (AG Nuernberg)
