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tree-vrp.c (find_case_label_index): Fix the binary search. 

2008-04-18  Rafael Espindola  <espindola@google.com>
	* tree-vrp.c (find_case_label_index): Fix the binary search.
	(find_case_label_range): New.
	(vrp_visit_switch_stmt): Use find_case_label_range.
	(simplify_switch_using_ranges): Use find_case_label_range.

From-SVN: r134452
This commit is contained in:
Rafael Avila de Espindola 2008-04-18 21:23:10 +00:00 committed by Rafael Espindola
parent 0ce7db600d
commit b7d8d447e5
2 changed files with 106 additions and 69 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2008-04-18 Rafael Espindola <espindola@google.com>
* tree-vrp.c (find_case_label_index): Fix the binary search.
(find_case_label_range): New.
(vrp_visit_switch_stmt): Use find_case_label_range.
(simplify_switch_using_ranges): Use find_case_label_range.
2008-04-18 Eric Botcazou <ebotcazou@adacore.com>
* gimplify.c (gimplify_modify_expr_rhs) <COND_EXPR>: Gimplify the LHS

169
gcc/tree-vrp.c
View File

@ -5528,48 +5528,52 @@ vrp_visit_cond_stmt (tree stmt, edge *taken_edge_p)
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. */
for (low = start_idx - 1, high = n - 1; high - low > 1; )
/* Find case label for minimum of the value range or the next one.
At each iteration we are searching in [low, high - 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;
@ -5577,10 +5581,66 @@ find_case_label_index (tree vec, size_t start_idx, tree val, size_t *idx)
}
}
*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
@ -5593,7 +5653,7 @@ vrp_visit_switch_stmt (tree stmt, edge *taken_edge_p)
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);
@ -5618,27 +5678,23 @@ vrp_visit_switch_stmt (tree stmt, edge *taken_edge_p)
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);
take_default = !find_case_label_range (vec, vr->min, vr->max, &i, &j);
/* 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);
/* 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 "
@ -6323,32 +6379,7 @@ simplify_switch_using_ranges (tree stmt)
/* 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