https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97172
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jakub at gcc dot gnu.org
--- Comment #24 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Completely untested routine that would allow unsharing expressions including
SAVE_EXPRs/TARGET_EXPRs, obviously then the result couldn't be used in the IL
for code generation, only for warnings.
It is basically unshare_expr, which afterwards when it sees SAVE_EXPRs or
TARGET_EXPRs
for the first time copies those and unshares their subtrees and when it sees
those
second and following time just reuses what it did before.
/* Helper function for fully_unshare_expr. Copy SAVE_EXPRs and TARGET_EXPRs
including their subtrees, but do that only once. */
static tree
fully_unshare_expr_r (tree *tp, int *walk_subtrees, void *data)
{
enum tree_code code = TREE_CODE (*tp);
if (code == SAVE_EXPR || code == TARGET_EXPR)
{
hash_map<tree, tree> **map = (hash_map<tree, tree> **) data;
*walk_subtrees = 0;
if (*map == NULL)
*map = new hash_map<tree, tree>;
tree &cached = (*map)->get_or_insert (*tp);
if (cached)
{
*tp = cached;
return NULL_TREE;
}
tree t = copy_node (*tp);
cached = t;
int len = 1;
if (code == TARGET_EXPR)
len = (TREE_OPERAND (t, 3) == TREE_OPERAND (t, 1)) ? 3 : 4;
for (int i = 0; i < len; i++)
{
TREE_OPERAND (t, i) = unshare_expr (TREE_OPERAND (t, i));
walk_tree (&TREE_OPERAND (t, i), fully_unshare_expr_r, data, NULL);
}
if (len == 3)
TREE_OPERAND (t, 3) = TREE_OPERAND (t, 1);
return NULL_TREE;
}
/* Stop at types, decls, constants like copy_tree_r. */
else if (TREE_CODE_CLASS (code) == tcc_type
|| TREE_CODE_CLASS (code) == tcc_declaration
|| TREE_CODE_CLASS (code) == tcc_constant)
*walk_subtrees = 0;
return NULL_TREE;
}
/* Like unshare_expr, but unshare also SAVE_EXPRs and TARGET_EXPRs.
After unsharing SAVE_EXPRs and TARGET_EXPRs, the returned expression
shouldn't be gimplified into the IL, as that could mean evaluating
side-effects multiple times. */
tree
fully_unshare_expr (tree expr)
{
hash_map <tree, tree> *map = NULL;
expr = unshare_expr (expr);
walk_tree (&expr, fully_unshare_expr_r, &map, NULL);
delete map;
return expr;
}
