#include "tree-iterator.h"
#include "tree-inline.h"
#include "diagnostic.h"
+#include "tree-pretty-print.h"
#include "langhooks.h"
#include "langhooks-def.h"
#include "tree-flow.h"
#include "except.h"
#include "hashtab.h"
#include "flags.h"
-#include "real.h"
#include "function.h"
#include "output.h"
#include "expr.h"
annotate_one_with_location (gs, location);
}
}
-
-
-/* Similar to copy_tree_r() but do not copy SAVE_EXPR or TARGET_EXPR nodes.
+\f
+/* This page contains routines to unshare tree nodes, i.e. to duplicate tree
+ nodes that are referenced more than once in GENERIC functions. This is
+ necessary because gimplification (translation into GIMPLE) is performed
+ by modifying tree nodes in-place, so gimplication of a shared node in a
+ first context could generate an invalid GIMPLE form in a second context.
+
+ This is achieved with a simple mark/copy/unmark algorithm that walks the
+ GENERIC representation top-down, marks nodes with TREE_VISITED the first
+ time it encounters them, duplicates them if they already have TREE_VISITED
+ set, and finally removes the TREE_VISITED marks it has set.
+
+ The algorithm works only at the function level, i.e. it generates a GENERIC
+ representation of a function with no nodes shared within the function when
+ passed a GENERIC function (except for nodes that are allowed to be shared).
+
+ At the global level, it is also necessary to unshare tree nodes that are
+ referenced in more than one function, for the same aforementioned reason.
+ This requires some cooperation from the front-end. There are 2 strategies:
+
+ 1. Manual unsharing. The front-end needs to call unshare_expr on every
+ expression that might end up being shared across functions.
+
+ 2. Deep unsharing. This is an extension of regular unsharing. Instead
+ of calling unshare_expr on expressions that might be shared across
+ functions, the front-end pre-marks them with TREE_VISITED. This will
+ ensure that they are unshared on the first reference within functions
+ when the regular unsharing algorithm runs. The counterpart is that
+ this algorithm must look deeper than for manual unsharing, which is
+ specified by LANG_HOOKS_DEEP_UNSHARING.
+
+ If there are only few specific cases of node sharing across functions, it is
+ probably easier for a front-end to unshare the expressions manually. On the
+ contrary, if the expressions generated at the global level are as widespread
+ as expressions generated within functions, deep unsharing is very likely the
+ way to go. */
+
+/* Similar to copy_tree_r but do not copy SAVE_EXPR or TARGET_EXPR nodes.
These nodes model computations that should only be done once. If we
were to unshare something like SAVE_EXPR(i++), the gimplification
process would create wrong code. */
static tree
mostly_copy_tree_r (tree *tp, int *walk_subtrees, void *data)
{
- enum tree_code code = TREE_CODE (*tp);
- /* Don't unshare types, decls, constants and SAVE_EXPR nodes. */
- if (TREE_CODE_CLASS (code) == tcc_type
- || TREE_CODE_CLASS (code) == tcc_declaration
- || TREE_CODE_CLASS (code) == tcc_constant
- || code == SAVE_EXPR || code == TARGET_EXPR
- /* We can't do anything sensible with a BLOCK used as an expression,
- but we also can't just die when we see it because of non-expression
- uses. So just avert our eyes and cross our fingers. Silly Java. */
- || code == BLOCK)
+ tree t = *tp;
+ enum tree_code code = TREE_CODE (t);
+
+ /* Do not copy SAVE_EXPR or TARGET_EXPR nodes themselves, but copy
+ their subtrees if we can make sure to do it only once. */
+ if (code == SAVE_EXPR || code == TARGET_EXPR)
+ {
+ if (data && !pointer_set_insert ((struct pointer_set_t *)data, t))
+ ;
+ else
+ *walk_subtrees = 0;
+ }
+
+ /* 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
+ /* We can't do anything sensible with a BLOCK used as an
+ expression, but we also can't just die when we see it
+ because of non-expression uses. So we avert our eyes
+ and cross our fingers. Silly Java. */
+ || code == BLOCK)
*walk_subtrees = 0;
+
+ /* Cope with the statement expression extension. */
+ else if (code == STATEMENT_LIST)
+ ;
+
+ /* Leave the bulk of the work to copy_tree_r itself. */
else
{
gcc_assert (code != BIND_EXPR);
- copy_tree_r (tp, walk_subtrees, data);
+ copy_tree_r (tp, walk_subtrees, NULL);
}
return NULL_TREE;
/* Callback for walk_tree to unshare most of the shared trees rooted at
*TP. If *TP has been visited already (i.e., TREE_VISITED (*TP) == 1),
- then *TP is deep copied by calling copy_tree_r.
-
- This unshares the same trees as copy_tree_r with the exception of
- SAVE_EXPR nodes. These nodes model computations that should only be
- done once. If we were to unshare something like SAVE_EXPR(i++), the
- gimplification process would create wrong code. */
+ then *TP is deep copied by calling mostly_copy_tree_r. */
static tree
-copy_if_shared_r (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
- void *data ATTRIBUTE_UNUSED)
+copy_if_shared_r (tree *tp, int *walk_subtrees, void *data)
{
tree t = *tp;
enum tree_code code = TREE_CODE (t);
any deeper. */
else if (TREE_VISITED (t))
{
- walk_tree (tp, mostly_copy_tree_r, NULL, NULL);
+ walk_tree (tp, mostly_copy_tree_r, data, NULL);
*walk_subtrees = 0;
}
- /* Otherwise, mark the tree as visited and keep looking. */
+ /* Otherwise, mark the node as visited and keep looking. */
else
TREE_VISITED (t) = 1;
return NULL_TREE;
}
-static tree
-unmark_visited_r (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
- void *data ATTRIBUTE_UNUSED)
-{
- if (TREE_VISITED (*tp))
- TREE_VISITED (*tp) = 0;
- else
- *walk_subtrees = 0;
+/* Unshare most of the shared trees rooted at *TP. */
- return NULL_TREE;
+static inline void
+copy_if_shared (tree *tp)
+{
+ /* If the language requires deep unsharing, we need a pointer set to make
+ sure we don't repeatedly unshare subtrees of unshareable nodes. */
+ struct pointer_set_t *visited
+ = lang_hooks.deep_unsharing ? pointer_set_create () : NULL;
+ walk_tree (tp, copy_if_shared_r, visited, NULL);
+ if (visited)
+ pointer_set_destroy (visited);
}
/* Unshare all the trees in BODY_P, a pointer into the body of FNDECL, and the
{
struct cgraph_node *cgn = cgraph_node (fndecl);
- walk_tree (body_p, copy_if_shared_r, NULL, NULL);
+ copy_if_shared (body_p);
+
if (body_p == &DECL_SAVED_TREE (fndecl))
for (cgn = cgn->nested; cgn; cgn = cgn->next_nested)
unshare_body (&DECL_SAVED_TREE (cgn->decl), cgn->decl);
}
+/* Callback for walk_tree to unmark the visited trees rooted at *TP.
+ Subtrees are walked until the first unvisited node is encountered. */
+
+static tree
+unmark_visited_r (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
+{
+ tree t = *tp;
+
+ /* If this node has been visited, unmark it and keep looking. */
+ if (TREE_VISITED (t))
+ TREE_VISITED (t) = 0;
+
+ /* Otherwise, don't look any deeper. */
+ else
+ *walk_subtrees = 0;
+
+ return NULL_TREE;
+}
+
+/* Unmark the visited trees rooted at *TP. */
+
+static inline void
+unmark_visited (tree *tp)
+{
+ walk_tree (tp, unmark_visited_r, NULL, NULL);
+}
+
/* Likewise, but mark all trees as not visited. */
static void
{
struct cgraph_node *cgn = cgraph_node (fndecl);
- walk_tree (body_p, unmark_visited_r, NULL, NULL);
+ unmark_visited (body_p);
+
if (body_p == &DECL_SAVED_TREE (fndecl))
for (cgn = cgn->nested; cgn; cgn = cgn->next_nested)
unvisit_body (&DECL_SAVED_TREE (cgn->decl), cgn->decl);
&& !TREE_STATIC (decl) && !DECL_EXTERNAL (decl)
&& decl_function_context (decl) == current_function_decl)
{
- gcc_assert (errorcount || sorrycount);
+ gcc_assert (seen_error ());
return GS_ERROR;
}
if (notify_temp_creation)
return GS_ERROR;
- walk_tree (&ctor, force_labels_r, NULL, NULL);
- TREE_OPERAND (*expr_p, 1) = tree_output_constant_def (ctor);
+ walk_tree (&ctor, force_labels_r, NULL, NULL);
+ ctor = tree_output_constant_def (ctor);
+ if (!useless_type_conversion_p (type, TREE_TYPE (ctor)))
+ ctor = build1 (VIEW_CONVERT_EXPR, type, ctor);
+ TREE_OPERAND (*expr_p, 1) = ctor;
/* This is no longer an assignment of a CONSTRUCTOR, but
we still may have processing to do on the LHS. So
/* Errors can result in improperly nested cleanups. Which results in
confusion when trying to resolve the GIMPLE_WITH_CLEANUP_EXPR. */
- if (errorcount || sorrycount)
+ if (seen_error ())
return;
if (gimple_conditional_context ())
gcc_assert (gimplify_ctxp == NULL);
#ifdef ENABLE_TYPES_CHECKING
- if (!errorcount && !sorrycount)
+ if (!seen_error ())
verify_types_in_gimple_seq (gimple_bind_body (outer_bind));
#endif
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