This merges the last conversion pattern from tree-ssa-forwprop.c. Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.
Richard. 2014-11-10 Richard Biener <rguent...@suse.de> * match.pd: Implement pattern from simplify_conversion_from_bitmask. * tree-ssa-forwprop.c (simplify_conversion_from_bitmask): Remove. (pass_forwprop::execute): Do not call simplify_conversion_from_bitmask. Index: trunk/gcc/match.pd =================================================================== *** trunk.orig/gcc/match.pd 2014-11-10 10:15:49.325550358 +0100 --- trunk/gcc/match.pd 2014-11-10 10:17:12.413546722 +0100 *************** along with GCC; see the file COPYING3. *** 431,433 **** --- 431,445 ---- (unsigned) significand_size (TYPE_MODE (inter_type)) >= inside_prec - !inside_unsignedp) (convert @0)))))) + + /* If we have a narrowing conversion to an integral type that is fed by a + BIT_AND_EXPR, we might be able to remove the BIT_AND_EXPR if it merely + masks off bits outside the final type (and nothing else). */ + (simplify + (convert (bit_and @0 INTEGER_CST@1)) + (if (INTEGRAL_TYPE_P (type) + && INTEGRAL_TYPE_P (TREE_TYPE (@0)) + && TYPE_PRECISION (type) <= TYPE_PRECISION (TREE_TYPE (@0)) + && operand_equal_p (@1, build_low_bits_mask (TREE_TYPE (@1), + TYPE_PRECISION (type)), 0)) + (convert @0))) Index: trunk/gcc/tree-ssa-forwprop.c =================================================================== *** trunk.orig/gcc/tree-ssa-forwprop.c 2014-11-10 10:15:49.655550343 +0100 --- trunk/gcc/tree-ssa-forwprop.c 2014-11-10 10:20:47.391537314 +0100 *************** bailout: *** 1214,1291 **** } - /* GSI_P points to a statement which performs a narrowing integral - conversion. - - Look for cases like: - - t = x & c; - y = (T) t; - - Turn them into: - - t = x & c; - y = (T) x; - - If T is narrower than X's type and C merely masks off bits outside - of (T) and nothing else. - - Normally we'd let DCE remove the dead statement. But no DCE runs - after the last forwprop/combine pass, so we remove the obviously - dead code ourselves. - - Return TRUE if a change was made, FALSE otherwise. */ - - static bool - simplify_conversion_from_bitmask (gimple_stmt_iterator *gsi_p) - { - gimple stmt = gsi_stmt (*gsi_p); - gimple rhs_def_stmt = SSA_NAME_DEF_STMT (gimple_assign_rhs1 (stmt)); - - /* See if the input for the conversion was set via a BIT_AND_EXPR and - the only use of the BIT_AND_EXPR result is the conversion. */ - if (is_gimple_assign (rhs_def_stmt) - && gimple_assign_rhs_code (rhs_def_stmt) == BIT_AND_EXPR - && has_single_use (gimple_assign_lhs (rhs_def_stmt))) - { - tree rhs_def_operand1 = gimple_assign_rhs1 (rhs_def_stmt); - tree rhs_def_operand2 = gimple_assign_rhs2 (rhs_def_stmt); - tree lhs_type = TREE_TYPE (gimple_assign_lhs (stmt)); - - /* Now verify suitability of the BIT_AND_EXPR's operands. - The first must be an SSA_NAME that we can propagate and the - second must be an integer constant that masks out all the - bits outside the final result's type, but nothing else. */ - if (TREE_CODE (rhs_def_operand1) == SSA_NAME - && ! SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs_def_operand1) - && TREE_CODE (rhs_def_operand2) == INTEGER_CST - && operand_equal_p (rhs_def_operand2, - build_low_bits_mask (TREE_TYPE (rhs_def_operand2), - TYPE_PRECISION (lhs_type)), - 0)) - { - /* This is an optimizable case. Replace the source operand - in the conversion with the first source operand of the - BIT_AND_EXPR. */ - gimple_assign_set_rhs1 (stmt, rhs_def_operand1); - stmt = gsi_stmt (*gsi_p); - update_stmt (stmt); - - /* There is no DCE after the last forwprop pass. It's - easy to clean up the first order effects here. */ - gimple_stmt_iterator si; - si = gsi_for_stmt (rhs_def_stmt); - gsi_remove (&si, true); - fwprop_invalidate_lattice (gimple_get_lhs (rhs_def_stmt)); - release_defs (rhs_def_stmt); - return true; - } - } - - return false; - } - - /* Helper function for simplify_gimple_switch. Remove case labels that have values outside the range of the new type. */ --- 1214,1219 ---- *************** pass_forwprop::execute (function *fun) *** 2940,2963 **** && maybe_clean_or_replace_eh_stmt (stmt, stmt)) bitmap_set_bit (to_purge, bb->index); } - else if (CONVERT_EXPR_CODE_P (code) - || code == FLOAT_EXPR - || code == FIX_TRUNC_EXPR) - { - /* If we have a narrowing conversion to an integral - type that is fed by a BIT_AND_EXPR, we might be - able to remove the BIT_AND_EXPR if it merely - masks off bits outside the final type (and nothing - else. */ - tree outer_type = TREE_TYPE (gimple_assign_lhs (stmt)); - tree inner_type = TREE_TYPE (gimple_assign_rhs1 (stmt)); - if (TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME - && INTEGRAL_TYPE_P (outer_type) - && INTEGRAL_TYPE_P (inner_type) - && (TYPE_PRECISION (outer_type) - <= TYPE_PRECISION (inner_type))) - changed = simplify_conversion_from_bitmask (&gsi); - } else if (code == VEC_PERM_EXPR) { int did_something = simplify_permutation (&gsi); --- 2868,2873 ----