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For some dumb reason I thought handling threading through a SWITCH_EXPR
was hard in VRP; that's definitely not the case, it's no more difficult
than handling a COND_EXPR.
This patch allows tree-vrp.c to thread through a SWITCH_EXPR when we
know the switch index via a particular path. Most of these would have
eventually been caught by DOM, but we get to pick up more secondary
effects if we can catch them in VRP.
Bootstrapped and regression tested on x86_64-unknown-linux-gnu. OK for
trunk?
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* tree-vrp.c (identify_jump_threads): Handle GIMPLE_SWITCH too.
Index: tree-vrp.c
===================================================================
*** tree-vrp.c (revision 172644)
--- tree-vrp.c (working copy)
*************** identify_jump_threads (void)
*** 7555,7579 ****
may be some value in handling SWITCH_EXPR here, I doubt it's
terribly important. */
last = gsi_stmt (gsi_last_bb (bb));
- if (gimple_code (last) != GIMPLE_COND)
- continue;
! /* We're basically looking for any kind of conditional with
integral or pointer type arguments. Note the type of the second
argument will be the same as the first argument, so no need to
check it explicitly. */
! if (TREE_CODE (gimple_cond_lhs (last)) == SSA_NAME
! && (INTEGRAL_TYPE_P (TREE_TYPE (gimple_cond_lhs (last)))
! || POINTER_TYPE_P (TREE_TYPE (gimple_cond_lhs (last))))
! && (TREE_CODE (gimple_cond_rhs (last)) == SSA_NAME
! || is_gimple_min_invariant (gimple_cond_rhs (last))))
{
edge_iterator ei;
/* We've got a block with multiple predecessors and multiple
! successors which also ends in a suitable conditional. For
! each predecessor, see if we can thread it to a specific
! successor. */
FOR_EACH_EDGE (e, ei, bb->preds)
{
/* Do not thread across back edges or abnormal edges
--- 7555,7579 ----
may be some value in handling SWITCH_EXPR here, I doubt it's
terribly important. */
last = gsi_stmt (gsi_last_bb (bb));
! /* We're basically looking for a switch or any kind of conditional with
integral or pointer type arguments. Note the type of the second
argument will be the same as the first argument, so no need to
check it explicitly. */
! if (gimple_code (last) == GIMPLE_SWITCH
! || (gimple_code (last) == GIMPLE_COND
! && TREE_CODE (gimple_cond_lhs (last)) == SSA_NAME
! && (INTEGRAL_TYPE_P (TREE_TYPE (gimple_cond_lhs (last)))
! || POINTER_TYPE_P (TREE_TYPE (gimple_cond_lhs (last))))
! && (TREE_CODE (gimple_cond_rhs (last)) == SSA_NAME
! || is_gimple_min_invariant (gimple_cond_rhs (last)))))
{
edge_iterator ei;
/* We've got a block with multiple predecessors and multiple
! successors which also ends in a suitable conditional or
! switch statement. For each predecessor, see if we can thread
! it to a specific successor. */
FOR_EACH_EDGE (e, ei, bb->preds)
{
/* Do not thread across back edges or abnormal edges
