return (*taken_edge_p) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
}
+/* Searches the case label vector VEC for the index *IDX of the CASE_LABEL
+ that includes the value VAL. The search is restricted to the range
+ [START_IDX, n - 2] where n is the size of VEC (n - 1 is the default label).
-/* Searches the case label vector VEC for the index *IDX the CASE_LABEL
- includes the value VAL. The search starts at index START_IDX and
- true is returned if *IDX corresponds to such an index. False is
- returned in case VAL hits the default case label and *IDX in this
- case is the next higher or the next lower case label index. */
+ If there is a CASE_LABEL for VAL, its index is placed in IDX and true is
+ returned.
+
+ If there is no CASE_LABEL for VAL and the is one that is larger than VAL,
+ it is placed in IDX and false is returned.
+
+ If VAL is larger than any CASE_LABEL, n - 1 is placed on IDX and false is
+ returned. */
static bool
find_case_label_index (tree vec, size_t start_idx, tree val, size_t *idx)
{
size_t n = TREE_VEC_LENGTH (vec);
- size_t low, high, i = start_idx;
+ size_t low, high;
+
+ /* Find case label for minimum of the value range or the next one.
+ At each iteration we are searching in [low, high - 1]. */
- /* Find case label for minimum of the value range or the next one. */
- for (low = start_idx - 1, high = n - 1; high - low > 1; )
+ for (low = start_idx, high = n - 1; high != low; )
{
tree t;
int cmp;
- i = (high + low) / 2;
+ /* Note that i != high, so we never ask for n - 1. */
+ size_t i = (high + low) / 2;
t = TREE_VEC_ELT (vec, i);
/* Cache the result of comparing CASE_LOW and val. */
cmp = tree_int_cst_compare (CASE_LOW (t), val);
- if (cmp > 0)
+ if (cmp == 0)
+ {
+ /* Ranges cannot be empty. */
+ *idx = i;
+ return true;
+ }
+ else if (cmp > 0)
high = i;
else
- low = i;
-
- if (CASE_HIGH (t) == NULL)
- {
- /* A singe-valued case label. */
- if (cmp == 0)
- {
- *idx = i;
- return true;
- }
- }
- else
- {
- /* A case range. We can only handle integer ranges. */
- if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
+ {
+ low = i + 1;
+ if (CASE_HIGH (t) != NULL
+ && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
{
*idx = i;
return true;
}
}
- *idx = i;
+ *idx = high;
return false;
}
+/* Searches the case label vector VEC for the range of CASE_LABELs that is used
+ for values between MIN and MAX. The first index is placed in MIN_IDX. The
+ last index is placed in MAX_IDX. If the range of CASE_LABELs is empty
+ then MAX_IDX < MIN_IDX.
+ Returns true if the default label is not needed. */
+
+static bool
+find_case_label_range (tree vec, tree min, tree max, size_t *min_idx, size_t *max_idx)
+{
+ size_t i, j;
+ bool min_take_default = !find_case_label_index (vec, 0, min, &i);
+ bool max_take_default = !find_case_label_index (vec, i, max, &j);
+
+ if (i == j
+ && min_take_default
+ && max_take_default)
+ {
+ /* Only the default case label reached.
+ Return an empty range. */
+ *min_idx = 1;
+ *max_idx = 0;
+ return false;
+ }
+ else
+ {
+ bool take_default = min_take_default || max_take_default;
+ tree low, high;
+ size_t k;
+
+ if (max_take_default)
+ j--;
+
+ /* If the case label range is continuous, we do not need
+ the default case label. Verify that. */
+ 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));
+ }
+
+ *min_idx = i;
+ *max_idx = j;
+ return !take_default;
+ }
+}
+
/* Visit switch statement STMT. If we can determine which edge
will be taken out of STMT's basic block, record it in
*TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
value_range_t *vr;
size_t i = 0, j = 0, n;
tree vec;
- bool min_take_default, max_take_default;
+ bool take_default;
*taken_edge_p = NULL;
op = TREE_OPERAND (stmt, 0);
vec = SWITCH_LABELS (stmt);
n = TREE_VEC_LENGTH (vec);
- /* Find case label for minimum of the value range or the next one. */
- min_take_default = !find_case_label_index (vec, 0, vr->min, &i);
-
- /* Find case label for maximum of the value range or the previous one. */
- max_take_default = !find_case_label_index (vec, i, vr->max, &j);
+ take_default = !find_case_label_range (vec, vr->min, vr->max, &i, &j);
- /* Check if we reach the default label only. */
+ /* Check if the range spans no CASE_LABEL. If so, we only reach the default
+ label */
if (j < i)
- val = TREE_VEC_ELT (vec, n - 1);
- /* Check if we reach exactly one label and not the default label. */
- else if (i == j
- && !min_take_default
- && !max_take_default)
- val = TREE_VEC_ELT (vec, i);
+ {
+ gcc_assert (take_default);
+ val = TREE_VEC_ELT (vec, n - 1);
+ }
else
{
- /* Check if labels with index i to j are all reaching the same label.
- If we don't hit a single case label only, the default case also has
- to branch to the same label. */
+ /* Check if labels with index i to j and maybe the default label
+ are all reaching the same label. */
+
val = TREE_VEC_ELT (vec, i);
- if (CASE_LABEL (TREE_VEC_ELT (vec, n - 1)) != CASE_LABEL (val))
+ if (take_default
+ && CASE_LABEL (TREE_VEC_ELT (vec, n - 1)) != CASE_LABEL (val))
{
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, " not a single destination for this "
/* 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));
- }
- }
+ take_default = !find_case_label_range (vec, vr->min, vr->max, &i, &j);
/* Bail out if this is just all edges taken. */
if (i == 0
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