From b7814a183ca564e2d8cf21c12364d13d8f1226a2 Mon Sep 17 00:00:00 2001
From: Richard Guenther <rguenther@suse.de>
Date: Wed, 2 Apr 2008 12:54:08 +0000
Subject: [PATCH] re PR tree-optimization/14495 ([tree-ssa] Propagate range
info into a switch statement)
2008-04-02 Richard Guenther <rguenther@suse.de>
PR tree-optimization/14495
PR tree-optimization/34793
* tree-vrp.c (struct switch_update): New structure.
(to_remove_edges, to_update_switch_stmts): New VECs.
(simplify_switch_using_ranges): New function. Remove not taken
case labels and edges.
(simplify_stmt_using_ranges): Call it.
(identify_jump_threads): Mark edges we have queued for removal
so we don't thread them.
(execute_vrp): Remove edges queued for removal, update SWITCH_STMT
case label vector.
* tree-cfg.c (group_case_labels): Deal with missing default label.
(tree_verify_flow_info): Allow missing default label.
* stmt.c (emit_case_bit_tests): Deal with NULL default_label.
(emit_case_nodes): Likewise.
(expand_case): Do not rely on the default label to be present.
* expr.c (try_casesi): Deal with NULL default_label.
(do_tablejump): Likewise.
* gcc.dg/tree-ssa/vrp41.c: New testcase.
* gcc.dg/tree-ssa/vrp42.c: Likewise.
From-SVN: r133835
---
gcc/ChangeLog | 21 ++++
gcc/expr.c | 10 +-
gcc/stmt.c | 47 +++++----
gcc/testsuite/ChangeLog | 7 ++
gcc/testsuite/gcc.dg/tree-ssa/vrp41.c | 27 +++++
gcc/testsuite/gcc.dg/tree-ssa/vrp42.c | 22 ++++
gcc/tree-cfg.c | 40 ++++---
gcc/tree-vrp.c | 145 +++++++++++++++++++++++++-
8 files changed, 276 insertions(+), 43 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/vrp41.c
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/vrp42.c
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index c9d8a4812a41..2bd5c04b214d 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,24 @@
+2008-04-02 Richard Guenther <rguenther@suse.de>
+
+ PR tree-optimization/14495
+ PR tree-optimization/34793
+ * tree-vrp.c (struct switch_update): New structure.
+ (to_remove_edges, to_update_switch_stmts): New VECs.
+ (simplify_switch_using_ranges): New function. Remove not taken
+ case labels and edges.
+ (simplify_stmt_using_ranges): Call it.
+ (identify_jump_threads): Mark edges we have queued for removal
+ so we don't thread them.
+ (execute_vrp): Remove edges queued for removal, update SWITCH_STMT
+ case label vector.
+ * tree-cfg.c (group_case_labels): Deal with missing default label.
+ (tree_verify_flow_info): Allow missing default label.
+ * stmt.c (emit_case_bit_tests): Deal with NULL default_label.
+ (emit_case_nodes): Likewise.
+ (expand_case): Do not rely on the default label to be present.
+ * expr.c (try_casesi): Deal with NULL default_label.
+ (do_tablejump): Likewise.
+
2008-04-02 Richard Guenther <rguenther@suse.de>
PR tree-optimization/14495
diff --git a/gcc/expr.c b/gcc/expr.c
index dbb2b4c468cc..a2bd86c4d091 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -9851,8 +9851,9 @@ try_casesi (tree index_type, tree index_expr, tree minval, tree range,
index_expr, minval);
minval = integer_zero_node;
index = expand_normal (index_expr);
- emit_cmp_and_jump_insns (rangertx, index, LTU, NULL_RTX,
- omode, 1, default_label);
+ if (default_label)
+ emit_cmp_and_jump_insns (rangertx, index, LTU, NULL_RTX,
+ omode, 1, default_label);
/* Now we can safely truncate. */
index = convert_to_mode (index_mode, index, 0);
}
@@ -9931,8 +9932,9 @@ do_tablejump (rtx index, enum machine_mode mode, rtx range, rtx table_label,
or equal to the minimum value of the range and less than or equal to
the maximum value of the range. */
- emit_cmp_and_jump_insns (index, range, GTU, NULL_RTX, mode, 1,
- default_label);
+ if (default_label)
+ emit_cmp_and_jump_insns (index, range, GTU, NULL_RTX, mode, 1,
+ default_label);
/* If index is in range, it must fit in Pmode.
Convert to Pmode so we can index with it. */
diff --git a/gcc/stmt.c b/gcc/stmt.c
index 35ba37b1c26b..6f8d4948d550 100644
--- a/gcc/stmt.c
+++ b/gcc/stmt.c
@@ -2258,8 +2258,9 @@ emit_case_bit_tests (tree index_type, tree index_expr, tree minval,
mode = TYPE_MODE (index_type);
expr = expand_normal (range);
- emit_cmp_and_jump_insns (index, expr, GTU, NULL_RTX, mode, 1,
- default_label);
+ if (default_label)
+ emit_cmp_and_jump_insns (index, expr, GTU, NULL_RTX, mode, 1,
+ default_label);
index = convert_to_mode (word_mode, index, 0);
index = expand_binop (word_mode, ashl_optab, const1_rtx,
@@ -2274,7 +2275,8 @@ emit_case_bit_tests (tree index_type, tree index_expr, tree minval,
word_mode, 1, test[i].label);
}
- emit_jump (default_label);
+ if (default_label)
+ emit_jump (default_label);
}
#ifndef HAVE_casesi
@@ -2320,7 +2322,7 @@ expand_case (tree exp)
struct case_node *case_list = 0;
/* Label to jump to if no case matches. */
- tree default_label_decl;
+ tree default_label_decl = NULL_TREE;
alloc_pool case_node_pool = create_alloc_pool ("struct case_node pool",
sizeof (struct case_node),
@@ -2338,18 +2340,21 @@ expand_case (tree exp)
{
tree elt;
bitmap label_bitmap;
+ int vl = TREE_VEC_LENGTH (vec);
/* cleanup_tree_cfg removes all SWITCH_EXPR with their index
expressions being INTEGER_CST. */
gcc_assert (TREE_CODE (index_expr) != INTEGER_CST);
- /* The default case is at the end of TREE_VEC. */
- elt = TREE_VEC_ELT (vec, TREE_VEC_LENGTH (vec) - 1);
- gcc_assert (!CASE_HIGH (elt));
- gcc_assert (!CASE_LOW (elt));
- default_label_decl = CASE_LABEL (elt);
+ /* The default case, if ever taken, is at the end of TREE_VEC. */
+ elt = TREE_VEC_ELT (vec, vl - 1);
+ if (!CASE_LOW (elt) && !CASE_HIGH (elt))
+ {
+ default_label_decl = CASE_LABEL (elt);
+ --vl;
+ }
- for (i = TREE_VEC_LENGTH (vec) - 1; --i >= 0; )
+ for (i = vl - 1; i >= 0; --i)
{
tree low, high;
elt = TREE_VEC_ELT (vec, i);
@@ -2368,7 +2373,8 @@ expand_case (tree exp)
before_case = start = get_last_insn ();
- default_label = label_rtx (default_label_decl);
+ if (default_label_decl)
+ default_label = label_rtx (default_label_decl);
/* Get upper and lower bounds of case values. */
@@ -2413,7 +2419,8 @@ expand_case (tree exp)
type, so we may still get a zero here. */
if (count == 0)
{
- emit_jump (default_label);
+ if (default_label)
+ emit_jump (default_label);
free_alloc_pool (case_node_pool);
return;
}
@@ -2509,7 +2516,8 @@ expand_case (tree exp)
&& estimate_case_costs (case_list));
balance_case_nodes (&case_list, NULL);
emit_case_nodes (index, case_list, default_label, index_type);
- emit_jump (default_label);
+ if (default_label)
+ emit_jump (default_label);
}
else
{
@@ -2559,9 +2567,10 @@ expand_case (tree exp)
}
/* Fill in the gaps with the default. */
- for (i = 0; i < ncases; i++)
- if (labelvec[i] == 0)
- labelvec[i] = gen_rtx_LABEL_REF (Pmode, default_label);
+ if (default_label)
+ for (i = 0; i < ncases; i++)
+ if (labelvec[i] == 0)
+ labelvec[i] = gen_rtx_LABEL_REF (Pmode, default_label);
/* Output the table. */
emit_label (table_label);
@@ -3043,7 +3052,8 @@ emit_case_nodes (rtx index, case_node_ptr node, rtx default_label,
emit_case_nodes (index, node->left, default_label, index_type);
/* If left-hand subtree does nothing,
go to default. */
- emit_jump (default_label);
+ if (default_label)
+ emit_jump (default_label);
/* Code branches here for the right-hand subtree. */
expand_label (test_label);
@@ -3178,7 +3188,8 @@ emit_case_nodes (rtx index, case_node_ptr node, rtx default_label,
{
/* If the left-hand subtree fell through,
don't let it fall into the right-hand subtree. */
- emit_jump (default_label);
+ if (default_label)
+ emit_jump (default_label);
expand_label (test_label);
emit_case_nodes (index, node->right, default_label, index_type);
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 03ac5b43e38c..432e9e019a09 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,10 @@
+2008-04-02 Richard Guenther <rguenther@suse.de>
+
+ PR tree-optimization/14495
+ PR tree-optimization/34793
+ * gcc.dg/tree-ssa/vrp41.c: New testcase.
+ * gcc.dg/tree-ssa/vrp42.c: Likewise.
+
2008-04-02 Richard Guenther <rguenther@suse.de>
PR tree-optimization/14495
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/vrp41.c b/gcc/testsuite/gcc.dg/tree-ssa/vrp41.c
new file mode 100644
index 000000000000..d573fbb0a437
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/vrp41.c
@@ -0,0 +1,27 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-vrp1" } */
+
+void bar0 (void);
+void bar1 (void);
+void bar2 (void);
+void bar3 (void);
+
+void
+foo (int a)
+{
+ if (a < 100)
+ return;
+ if (200 < a)
+ return;
+
+ switch (a)
+ {
+ case 99: bar0 (); return;
+ case 100: bar1 (); return;
+ case 101: bar2 (); return;
+ case 102: bar3 (); return;
+ }
+}
+
+/* { dg-final { scan-tree-dump-not "case 99:" "vrp1" } } */
+/* { dg-final { cleanup-tree-dump "vrp1" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/vrp42.c b/gcc/testsuite/gcc.dg/tree-ssa/vrp42.c
new file mode 100644
index 000000000000..79eb22cb1e4f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/vrp42.c
@@ -0,0 +1,22 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -Wuninitialized" } */
+
+int foo(int val)
+{
+ int tmp;
+ if ((val > 5) && (val < 8))
+ {
+ switch (val)
+ {
+ case 6:
+ tmp = 1;
+ break;
+ case 7:
+ tmp = 2;
+ break;
+ }
+ return tmp; /* { dg-bogus "used uninitialized" } */
+ }
+ return 0;
+}
+
diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
index 944b31f3725e..70d0404bc0eb 100644
--- a/gcc/tree-cfg.c
+++ b/gcc/tree-cfg.c
@@ -1060,18 +1060,23 @@ group_case_labels (void)
tree labels = SWITCH_LABELS (stmt);
int old_size = TREE_VEC_LENGTH (labels);
int i, j, new_size = old_size;
- tree default_case = TREE_VEC_ELT (labels, old_size - 1);
- tree default_label;
+ tree default_case = NULL_TREE;
+ tree default_label = NULL_TREE;
/* The default label is always the last case in a switch
- statement after gimplification. */
- default_label = CASE_LABEL (default_case);
+ statement after gimplification if it was not optimized
+ away. */
+ if (!CASE_LOW (TREE_VEC_ELT (labels, old_size - 1))
+ && !CASE_HIGH (TREE_VEC_ELT (labels, old_size - 1)))
+ {
+ default_case = TREE_VEC_ELT (labels, old_size - 1);
+ default_label = CASE_LABEL (default_case);
+ old_size--;
+ }
- /* Look for possible opportunities to merge cases.
- Ignore the last element of the label vector because it
- must be the default case. */
+ /* Look for possible opportunities to merge cases. */
i = 0;
- while (i < old_size - 1)
+ while (i < old_size)
{
tree base_case, base_label, base_high;
base_case = TREE_VEC_ELT (labels, i);
@@ -1095,7 +1100,7 @@ group_case_labels (void)
/* Try to merge case labels. Break out when we reach the end
of the label vector or when we cannot merge the next case
label with the current one. */
- while (i < old_size - 1)
+ while (i < old_size)
{
tree merge_case = TREE_VEC_ELT (labels, i);
tree merge_label = CASE_LABEL (merge_case);
@@ -4604,13 +4609,16 @@ tree_verify_flow_info (void)
/* Verify that the case labels are sorted. */
prev = TREE_VEC_ELT (vec, 0);
- for (i = 1; i < n - 1; ++i)
+ for (i = 1; i < n; ++i)
{
tree c = TREE_VEC_ELT (vec, i);
if (! CASE_LOW (c))
{
- error ("found default case not at end of case vector");
- err = 1;
+ if (i != n - 1)
+ {
+ error ("found default case not at end of case vector");
+ err = 1;
+ }
continue;
}
if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
@@ -4624,11 +4632,9 @@ tree_verify_flow_info (void)
}
prev = c;
}
- if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
- {
- error ("no default case found at end of case vector");
- err = 1;
- }
+ /* VRP will remove the default case if it can prove it will
+ never be executed. So do not verify there always exists
+ a default case here. */
FOR_EACH_EDGE (e, ei, bb->succs)
{
diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
index 1d8ade783a9f..65635285df91 100644
--- a/gcc/tree-vrp.c
+++ b/gcc/tree-vrp.c
@@ -104,6 +104,16 @@ static value_range_t **vr_value;
node. */
static int *vr_phi_edge_counts;
+typedef struct {
+ tree stmt;
+ tree vec;
+} switch_update;
+
+static VEC (edge, heap) *to_remove_edges;
+DEF_VEC_O(switch_update);
+DEF_VEC_ALLOC_O(switch_update, heap);
+static VEC (switch_update, heap) *to_update_switch_stmts;
+
/* Return the maximum value for TYPEs base type. */
@@ -6298,6 +6308,106 @@ simplify_cond_using_ranges (tree stmt)
}
}
+/* Simplify a switch statement using the value range of the switch
+ argument. */
+
+static void
+simplify_switch_using_ranges (tree stmt)
+{
+ tree op = TREE_OPERAND (stmt, 0);
+ value_range_t *vr;
+ bool take_default;
+ edge e;
+ edge_iterator ei;
+ size_t i = 0, j = 0, n, n2;
+ tree vec, vec2;
+ switch_update su;
+
+ if (TREE_CODE (op) != SSA_NAME)
+ return;
+
+ vr = get_value_range (op);
+
+ /* We can only handle integer ranges. */
+ if (vr->type != VR_RANGE
+ || symbolic_range_p (vr))
+ return;
+
+ /* Find case label for min/max of the value range. */
+ vec = SWITCH_LABELS (stmt);
+ n = TREE_VEC_LENGTH (vec);
+ take_default = !find_case_label_index (vec, 0, vr->min, &i);
+ take_default |= !find_case_label_index (vec, i, vr->max, &j);
+
+ /* If the case label range is continuous, we do not need to
+ preserve the default case label. Verify that. */
+ if (!take_default && j > i)
+ {
+ tree low, high;
+ size_t k;
+
+ high = CASE_LOW (TREE_VEC_ELT (vec, i));
+ if (CASE_HIGH (TREE_VEC_ELT (vec, i)))
+ high = CASE_HIGH (TREE_VEC_ELT (vec, i));
+ for (k = i + 1; k <= j; ++k)
+ {
+ low = CASE_LOW (TREE_VEC_ELT (vec, k));
+ if (!integer_onep (int_const_binop (MINUS_EXPR, low, high, 0)))
+ {
+ take_default = true;
+ break;
+ }
+ high = low;
+ if (CASE_HIGH (TREE_VEC_ELT (vec, k)))
+ high = CASE_HIGH (TREE_VEC_ELT (vec, k));
+ }
+ }
+
+ /* Bail out if this is just all edges taken. */
+ if (i == 0
+ && j == n - 2
+ && take_default)
+ return;
+
+ /* Build a new vector of taken case labels. */
+ vec2 = make_tree_vec (j - i + 1 + (int)take_default);
+ for (n2 = 0; i <= j; ++i, ++n2)
+ TREE_VEC_ELT (vec2, n2) = TREE_VEC_ELT (vec, i);
+
+ /* Add the default edge, if necessary. */
+ if (take_default)
+ TREE_VEC_ELT (vec2, n2++) = TREE_VEC_ELT (vec, n - 1);
+
+ /* Mark needed edges. */
+ for (i = 0; i < n2; ++i)
+ {
+ e = find_edge (bb_for_stmt (stmt),
+ label_to_block (CASE_LABEL (TREE_VEC_ELT (vec2, i))));
+ e->aux = (void *)-1;
+ }
+
+ /* Queue not needed edges for later removal. */
+ FOR_EACH_EDGE (e, ei, bb_for_stmt (stmt)->succs)
+ {
+ if (e->aux == (void *)-1)
+ {
+ e->aux = NULL;
+ continue;
+ }
+
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file, "removing unreachable case label\n");
+ }
+ VEC_safe_push (edge, heap, to_remove_edges, e);
+ }
+
+ /* And queue an update for the stmt. */
+ su.stmt = stmt;
+ su.vec = vec2;
+ VEC_safe_push (switch_update, heap, to_update_switch_stmts, &su);
+}
+
/* Simplify STMT using ranges if possible. */
void
@@ -6324,9 +6434,9 @@ simplify_stmt_using_ranges (tree stmt)
}
else if (TREE_CODE (stmt) == COND_EXPR
&& COMPARISON_CLASS_P (COND_EXPR_COND (stmt)))
- {
- simplify_cond_using_ranges (stmt);
- }
+ simplify_cond_using_ranges (stmt);
+ else if (TREE_CODE (stmt) == SWITCH_EXPR)
+ simplify_switch_using_ranges (stmt);
}
/* Stack of dest,src equivalency pairs that need to be restored after
@@ -6378,6 +6488,8 @@ identify_jump_threads (void)
{
basic_block bb;
tree dummy;
+ int i;
+ edge e;
/* Ugh. When substituting values earlier in this pass we can
wipe the dominance information. So rebuild the dominator
@@ -6391,6 +6503,11 @@ identify_jump_threads (void)
recompute it. */
mark_dfs_back_edges ();
+ /* Do not thread across edges we are about to remove. Just marking
+ them as EDGE_DFS_BACK will do. */
+ for (i = 0; VEC_iterate (edge, to_remove_edges, i, e); ++i)
+ e->flags |= EDGE_DFS_BACK;
+
/* Allocate our unwinder stack to unwind any temporary equivalences
that might be recorded. */
stack = VEC_alloc (tree, heap, 20);
@@ -6436,7 +6553,6 @@ identify_jump_threads (void)
&& INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 1)))))
{
edge_iterator ei;
- edge e;
/* We've got a block with multiple predecessors and multiple
successors which also ends in a suitable conditional. For
@@ -6603,6 +6719,10 @@ record_numbers_of_iterations (void)
static unsigned int
execute_vrp (void)
{
+ int i;
+ edge e;
+ switch_update *su;
+
loop_optimizer_init (LOOPS_NORMAL | LOOPS_HAVE_RECORDED_EXITS);
rewrite_into_loop_closed_ssa (NULL, TODO_update_ssa);
scev_initialize ();
@@ -6620,10 +6740,27 @@ execute_vrp (void)
ranges are corrected. */
record_numbers_of_iterations ();
+ to_remove_edges = VEC_alloc (edge, heap, 10);
+ to_update_switch_stmts = VEC_alloc (switch_update, heap, 5);
+
vrp_initialize ();
ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node);
vrp_finalize ();
+ /* Remove dead edges from SWITCH_EXPR optimization. This leaves the
+ CFG in a broken state and requires a cfg_cleanup run. */
+ for (i = 0; VEC_iterate (edge, to_remove_edges, i, e); ++i)
+ remove_edge (e);
+ /* Update SWITCH_EXPR case label vector. */
+ for (i = 0; VEC_iterate (switch_update, to_update_switch_stmts, i, su); ++i)
+ SWITCH_LABELS (su->stmt) = su->vec;
+
+ if (VEC_length (edge, to_remove_edges) > 0)
+ free_dominance_info (CDI_DOMINATORS);
+
+ VEC_free (edge, heap, to_remove_edges);
+ VEC_free (switch_update, heap, to_update_switch_stmts);
+
/* ASSERT_EXPRs must be removed before finalizing jump threads
as finalizing jump threads calls the CFG cleanup code which
does not properly handle ASSERT_EXPRs. */
--
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