diff options
Diffstat (limited to 'gcc/tree-vrp.c')
| -rw-r--r-- | gcc/tree-vrp.c | 33 |
1 files changed, 30 insertions, 3 deletions
diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c index 284208b..5ad94b2 100644 --- a/gcc/tree-vrp.c +++ b/gcc/tree-vrp.c @@ -2641,7 +2641,10 @@ insert_range_assertions (void) } -/* Convert range assertion expressions into the implied copies. +/* Convert range assertion expressions into the implied copies and + copy propagate away the copies. Doing the trivial copy propagation + here avoids the need to run the full copy propagation pass after + VRP. FIXME, this will eventually lead to copy propagation removing the names that had useful range information attached to them. For @@ -2655,7 +2658,12 @@ insert_range_assertions (void) things like jump threading. The problem with keeping ASSERT_EXPRs around is that passes after - VRP need to handle them appropriately. */ + VRP need to handle them appropriately. + + Another approach would be to make the range information a first + class property of the SSA_NAME so that it can be queried from + any pass. This is made somewhat more complex by the need for + multiple ranges to be associated with one SSA_NAME. */ static void remove_range_assertions (void) @@ -2663,8 +2671,11 @@ remove_range_assertions (void) basic_block bb; block_stmt_iterator si; + /* Note that the BSI iterator bump happens at the bottom of the + loop and no bump is necessary if we're removing the statement + referenced by the current BSI. */ FOR_EACH_BB (bb) - for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si)) + for (si = bsi_start (bb); !bsi_end_p (si);) { tree stmt = bsi_stmt (si); @@ -2673,10 +2684,26 @@ remove_range_assertions (void) { tree rhs = TREE_OPERAND (stmt, 1); tree cond = fold (ASSERT_EXPR_COND (rhs)); + use_operand_p use_p; + imm_use_iterator iter; + gcc_assert (cond != boolean_false_node); TREE_OPERAND (stmt, 1) = ASSERT_EXPR_VAR (rhs); update_stmt (stmt); + + /* The statement is now a copy. Propagate the RHS into + every use of the LHS. */ + FOR_EACH_IMM_USE_SAFE (use_p, iter, TREE_OPERAND (stmt, 0)) + { + SET_USE (use_p, ASSERT_EXPR_VAR (rhs)); + update_stmt (USE_STMT (use_p)); + } + + /* And finally, remove the copy, it is not needed. */ + bsi_remove (&si); } + else + bsi_next (&si); } } |