This is a small cleanup of the duplicating comparison code. There is code generation difference but only for -O0 and -fno-tree-ter (both of which will be fixed in a later patch). The difference is instead of skipping the first use if the comparison uses are only in cond_expr we skip the last use. Also we go through the uses list in the opposite order now too.
The cleanups are the following: * Don't call has_single_use as we will do the loop anyways * Change the order of the checks slightly, it is better to check for cond_expr earlier * Use cond_exprs as a stack and pop from it. Skipping the top if the use is only from cond_expr. Bootstrapped and tested on x86_64-linux-gnu with no regressions. gcc/ChangeLog: * gimple-isel.cc (duplicate_comparison): Rename to ... (maybe_duplicate_comparison): This. Add check for use here rather than in its caller. (pass_gimple_isel::execute): Don't check how many uses the comparison had and call maybe_duplicate_comparison instead of duplicate_comparison. Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com> --- gcc/gimple-isel.cc | 38 ++++++++++++++++++++++++-------------- 1 file changed, 24 insertions(+), 14 deletions(-) diff --git a/gcc/gimple-isel.cc b/gcc/gimple-isel.cc index 327a78ea408..99bfc937bd5 100644 --- a/gcc/gimple-isel.cc +++ b/gcc/gimple-isel.cc @@ -399,34 +399,46 @@ gimple_expand_vec_cond_expr (struct function *fun, gimple_stmt_iterator *gsi, comparisons so RTL expansion with the help of TER can perform better if conversion. */ static void -duplicate_comparison (gassign *stmt, basic_block bb) +maybe_duplicate_comparison (gassign *stmt, basic_block bb) { imm_use_iterator imm_iter; use_operand_p use_p; auto_vec<gassign *, 4> cond_exprs; - unsigned cnt = 0; tree lhs = gimple_assign_lhs (stmt); + unsigned cnt = 0; + FOR_EACH_IMM_USE_FAST (use_p, imm_iter, lhs) { if (is_gimple_debug (USE_STMT (use_p))) continue; cnt++; + /* Add the use statement if it was a cond_expr. */ if (gimple_bb (USE_STMT (use_p)) == bb && is_gimple_assign (USE_STMT (use_p)) - && gimple_assign_rhs1_ptr (USE_STMT (use_p)) == use_p->use - && gimple_assign_rhs_code (USE_STMT (use_p)) == COND_EXPR) + && gimple_assign_rhs_code (USE_STMT (use_p)) == COND_EXPR + && gimple_assign_rhs1_ptr (USE_STMT (use_p)) == use_p->use) cond_exprs.safe_push (as_a <gassign *> (USE_STMT (use_p))); - } - for (unsigned i = cond_exprs.length () == cnt ? 1 : 0; - i < cond_exprs.length (); ++i) + } + + /* If the comparison has 0 or 1 uses, no reason to do anything. */ + if (cnt <= 1) + return; + + /* If we only use the expression inside cond_exprs in that BB, we don't + need to duplicate for one of them so pop the top. */ + if (cond_exprs.length () == cnt) + cond_exprs.pop(); + + while (!cond_exprs.is_empty()) { + auto old_top = cond_exprs.pop(); gassign *copy = as_a <gassign *> (gimple_copy (stmt)); tree new_def = duplicate_ssa_name (lhs, copy); gimple_assign_set_lhs (copy, new_def); - auto gsi2 = gsi_for_stmt (cond_exprs[i]); + auto gsi2 = gsi_for_stmt (old_top); gsi_insert_before (&gsi2, copy, GSI_SAME_STMT); - gimple_assign_set_rhs1 (cond_exprs[i], new_def); - update_stmt (cond_exprs[i]); + gimple_assign_set_rhs1 (old_top, new_def); + update_stmt (old_top); } } @@ -500,10 +512,8 @@ pass_gimple_isel::execute (struct function *fun) continue; tree_code code = gimple_assign_rhs_code (stmt); - tree lhs = gimple_assign_lhs (stmt); - if (TREE_CODE_CLASS (code) == tcc_comparison - && !has_single_use (lhs)) - duplicate_comparison (stmt, bb); + if (TREE_CODE_CLASS (code) == tcc_comparison) + maybe_duplicate_comparison (stmt, bb); } } -- 2.43.0