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Diffstat (limited to 'gcc/tree-nested.c')
| -rw-r--r-- | gcc/tree-nested.c | 1383 |
1 files changed, 1383 insertions, 0 deletions
diff --git a/gcc/tree-nested.c b/gcc/tree-nested.c new file mode 100644 index 00000000000..7b92a75db30 --- /dev/null +++ b/gcc/tree-nested.c @@ -0,0 +1,1383 @@ +/* Nested function decomposition for trees. + Copyright (C) 2004 Free Software Foundation, Inc. + + This file is part of GCC. + + GCC is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2, or (at your option) + any later version. + + GCC is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with GCC; see the file COPYING. If not, write to + the Free Software Foundation, 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. */ + +#include "config.h" +#include "system.h" +#include "coretypes.h" +#include "tm.h" +#include "tree.h" +#include "rtl.h" +#include "tm_p.h" +#include "function.h" +#include "tree-dump.h" +#include "tree-inline.h" +#include "tree-simple.h" +#include "tree-iterator.h" +#include "tree-flow.h" +#include "cgraph.h" +#include "expr.h" +#include "langhooks.h" +#include "ggc.h" + + +/* The object of this pass is to lower the representation of a set of nested + functions in order to expose all of the gory details of the various + nonlocal references. We want to do this sooner rather than later, in + order to give us more freedom in emitting all of the functions in question. + + Back in olden times, when gcc was young, we developed an insanely + complicated scheme whereby variables which were referenced nonlocally + were forced to live in the stack of the declaring function, and then + the nested functions magically discovered where these variables were + placed. In order for this scheme to function properly, it required + that the outer function be partially expanded, then we switch to + compiling the inner function, and once done with those we switch back + to compiling the outer function. Such delicate ordering requirements + makes it difficult to do whole translation unit optimizations + involving such functions. + + The implementation here is much more direct. Everything that can be + referenced by an inner function is a member of an explicitly created + structure herein called the "nonlocal frame struct". The incomming + static chain for a nested function is a pointer to this struct in + the parent. In this way, we settle on known offsets from a known + base, and so are decoupled from the logic that places objects in the + function's stack frame. More importantly, we don't have to wait for + that to happen -- since the compilation of the inner function is no + longer tied to a real stack frame, the nonlocal frame struct can be + allocated anywhere. Which means that the outer function is now + inlinable. + + Theory of operation here is very simple. Iterate over all the + statements in all the functions (depth first) several times, + allocating structures and fields on demand. In general we want to + examine inner functions first, so that we can avoid making changes + to outer functions which are unnecessary. + + The order of the passes matters a bit, in that later passes will be + skipped if it is discovered that the functions don't actually interact + at all. That is, they're nested in the lexical sense but could have + been written as independent functions without change. */ + + +struct var_map_elt +{ + tree old; + tree new; +}; + +struct nesting_info +{ + struct nesting_info *outer; + struct nesting_info *inner; + struct nesting_info *next; + + htab_t var_map; + tree context; + tree new_local_var_chain; + tree frame_type; + tree frame_decl; + tree chain_field; + tree chain_decl; + tree nl_goto_field; + + bool any_parm_remapped; + bool any_tramp_created; +}; + + +/* Hashing and equality functions for nesting_info->var_map. */ + +static hashval_t +var_map_hash (const void *x) +{ + const struct var_map_elt *a = x; + return htab_hash_pointer (a->old); +} + +static int +var_map_eq (const void *x, const void *y) +{ + const struct var_map_elt *a = x; + const struct var_map_elt *b = y; + return a->old == b->old; +} + +/* We're working in so many different function contexts simultaneously, + that create_tmp_var is dangerous. Prevent mishap. */ +#define create_tmp_var cant_use_create_tmp_var_here_dummy + +/* Like create_tmp_var, except record the variable for registration at + the given nesting level. */ + +static tree +create_tmp_var_for (struct nesting_info *info, tree type, const char *prefix) +{ + tree tmp_var; + +#if defined ENABLE_CHECKING + /* If the type is an array or a type which must be created by the + frontend, something is wrong. Note that we explicitly allow + incomplete types here, since we create them ourselves here. */ + if (TREE_CODE (type) == ARRAY_TYPE || TREE_ADDRESSABLE (type)) + abort (); + if (TYPE_SIZE_UNIT (type) + && TREE_CODE (TYPE_SIZE_UNIT (type)) != INTEGER_CST) + abort (); +#endif + + tmp_var = create_tmp_var_raw (type, prefix); + DECL_CONTEXT (tmp_var) = info->context; + TREE_CHAIN (tmp_var) = info->new_local_var_chain; + info->new_local_var_chain = tmp_var; + + return tmp_var; +} + +/* Take the address of EXP. Mark it for addressability as necessary. */ + +static tree +build_addr (tree exp) +{ + tree base = exp; + while (TREE_CODE (base) == COMPONENT_REF || TREE_CODE (base) == ARRAY_REF) + base = TREE_OPERAND (base, 0); + if (DECL_P (base)) + TREE_ADDRESSABLE (base) = 1; + + return build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (exp)), exp); +} + +/* Insert FIELD into TYPE, sorted by alignment requirements. */ + +static void +insert_field_into_struct (tree type, tree field) +{ + tree *p; + + DECL_CONTEXT (field) = type; + + for (p = &TYPE_FIELDS (type); *p ; p = &TREE_CHAIN (*p)) + if (DECL_ALIGN (field) >= DECL_ALIGN (*p)) + break; + + TREE_CHAIN (field) = *p; + *p = field; +} + +/* Build or return the RECORD_TYPE that describes the frame state that is + shared between INFO->CONTEXT and its nested functions. This record will + not be complete until finalize_nesting_tree; up until that point we'll + be adding fields as necessary. + + We also build the DECL that represents this frame in the function. */ + +static tree +get_frame_type (struct nesting_info *info) +{ + tree type = info->frame_type; + if (!type) + { + char *name; + + type = make_node (RECORD_TYPE); + + name = concat ("FRAME.", + IDENTIFIER_POINTER (DECL_NAME (info->context)), + NULL); + TYPE_NAME (type) = get_identifier (name); + free (name); + + info->frame_type = type; + info->frame_decl = create_tmp_var_for (info, type, "FRAME"); + } + return type; +} + +/* Return true if DECL should be referenced by pointer in the non-local + frame structure. */ + +static bool +use_pointer_in_frame (tree decl) +{ + if (TREE_CODE (decl) == PARM_DECL) + { + /* It's illegal to copy TREE_ADDRESSABLE, impossible to copy variable + sized decls, and inefficient to copy large aggregates. Don't bother + moving anything but scalar variables. */ + return AGGREGATE_TYPE_P (TREE_TYPE (decl)); + } + else + { + /* Variable sized types make things "interesting" in the frame. */ + return DECL_SIZE (decl) == NULL || !TREE_CONSTANT (DECL_SIZE (decl)); + } +} + +/* Given DECL, a non-locally accessed variable, find or create a field + in the non-local frame structure for the given nesting context. */ + +static tree +lookup_field_for_decl (struct nesting_info *info, tree decl, + enum insert_option insert) +{ + struct var_map_elt *elt, dummy; + void **slot; + tree field; + + dummy.old = decl; + slot = htab_find_slot (info->var_map, &dummy, insert); + if (!slot) + { + if (insert == INSERT) + abort (); + return NULL; + } + elt = *slot; + + if (!elt && insert == INSERT) + { + field = make_node (FIELD_DECL); + DECL_NAME (field) = DECL_NAME (decl); + + if (use_pointer_in_frame (decl)) + { + TREE_TYPE (field) = build_pointer_type (TREE_TYPE (decl)); + DECL_ALIGN (field) = TYPE_ALIGN (TREE_TYPE (field)); + DECL_NONADDRESSABLE_P (field) = 1; + } + else + { + TREE_TYPE (field) = TREE_TYPE (decl); + DECL_SOURCE_LOCATION (field) = DECL_SOURCE_LOCATION (decl); + DECL_ALIGN (field) = DECL_ALIGN (decl); + DECL_USER_ALIGN (field) = DECL_USER_ALIGN (decl); + TREE_ADDRESSABLE (field) = TREE_ADDRESSABLE (decl); + DECL_NONADDRESSABLE_P (field) = !TREE_ADDRESSABLE (decl); + TREE_THIS_VOLATILE (field) = TREE_THIS_VOLATILE (decl); + } + + insert_field_into_struct (get_frame_type (info), field); + + elt = xmalloc (sizeof (*elt)); + elt->old = decl; + elt->new = field; + *slot = elt; + + if (TREE_CODE (decl) == PARM_DECL) + info->any_parm_remapped = true; + } + else + field = elt ? elt->new : NULL; + + return field; +} + +/* Build or return the variable that holds the static chain within + INFO->CONTEXT. This variable may only be used within INFO->CONTEXT. */ + +static tree +get_chain_decl (struct nesting_info *info) +{ + tree decl = info->chain_decl; + if (!decl) + { + tree type; + + type = get_frame_type (info->outer); + type = build_pointer_type (type); + + /* Note that this variable is *not* entered into any BIND_EXPR; + the construction of this variable is handled specially in + expand_function_start and initialize_inlined_parameters. */ + decl = create_tmp_var_raw (type, "CHAIN"); + DECL_CONTEXT (decl) = info->context; + decl->decl.seen_in_bind_expr = 1; + + /* The initialization of CHAIN is not visible to the tree-ssa + analyzers and optimizers. Thus we do not want to issue + warnings for CHAIN. */ + TREE_NO_WARNING (decl) = 1; + + /* Tell tree-inline.c that we never write to this variable, so + it can copy-prop the replacement value immediately. */ + TREE_READONLY (decl) = 1; + + info->chain_decl = decl; + } + return decl; +} + +/* Build or return the field within the non-local frame state that holds + the static chain for INFO->CONTEXT. This is the way to walk back up + multiple nesting levels. */ + +static tree +get_chain_field (struct nesting_info *info) +{ + tree field = info->chain_field; + if (!field) + { + tree type = build_pointer_type (get_frame_type (info->outer)); + + field = make_node (FIELD_DECL); + DECL_NAME (field) = get_identifier ("__chain"); + TREE_TYPE (field) = type; + DECL_ALIGN (field) = TYPE_ALIGN (type); + DECL_NONADDRESSABLE_P (field) = 1; + + insert_field_into_struct (get_frame_type (info), field); + + info->chain_field = field; + } + return field; +} + +/* Copy EXP into a temporary. Allocate the temporary in the context of + INFO and insert the initialization statement before TSI. */ + +static tree +init_tmp_var (struct nesting_info *info, tree exp, tree_stmt_iterator *tsi) +{ + tree t, stmt; + + t = create_tmp_var_for (info, TREE_TYPE (exp), NULL); + stmt = build (MODIFY_EXPR, TREE_TYPE (t), t, exp); + SET_EXPR_LOCUS (stmt, EXPR_LOCUS (tsi_stmt (*tsi))); + tsi_link_before (tsi, stmt, TSI_SAME_STMT); + + return t; +} + +/* Similarly, but only do so to force EXP to satisfy is_gimple_val. */ + +static tree +gimplify_val (struct nesting_info *info, tree exp, tree_stmt_iterator *tsi) +{ + if (is_gimple_val (exp)) + return exp; + else + return init_tmp_var (info, exp, tsi); +} + +/* Build or return the type used to represent a nested function trampoline. */ + +static GTY(()) tree trampoline_type; + +static tree +get_trampoline_type (void) +{ + tree record, t; + unsigned align, size; + + if (trampoline_type) + return trampoline_type; + + align = TRAMPOLINE_ALIGNMENT; + size = TRAMPOLINE_SIZE; + + /* If we won't be able to guarantee alignment simply via TYPE_ALIGN, + then allocate extra space so that we can do dynamic alignment. */ + if (align > STACK_BOUNDARY) + { + size += ((align/BITS_PER_UNIT) - 1) & -(STACK_BOUNDARY/BITS_PER_UNIT); + align = STACK_BOUNDARY; + } + + t = build_index_type (build_int_2 (size - 1, 0)); + t = build_array_type (char_type_node, t); + t = build_decl (FIELD_DECL, get_identifier ("__data"), t); + DECL_ALIGN (t) = align; + DECL_USER_ALIGN (t) = 1; + + record = make_node (RECORD_TYPE); + TYPE_NAME (record) = get_identifier ("__builtin_trampoline"); + TYPE_FIELDS (record) = t; + layout_type (record); + + return record; +} + +/* Given DECL, a nested function, find or create a field in the non-local + frame structure for a trampoline for this function. */ + +static tree +lookup_tramp_for_decl (struct nesting_info *info, tree decl, + enum insert_option insert) +{ + struct var_map_elt *elt, dummy; + void **slot; + tree field; + + dummy.old = decl; + slot = htab_find_slot (info->var_map, &dummy, insert); + if (!slot) + { + if (insert == INSERT) + abort (); + return NULL; + } + elt = *slot; + + if (!elt && insert == INSERT) + { + field = make_node (FIELD_DECL); + DECL_NAME (field) = DECL_NAME (decl); + TREE_TYPE (field) = get_trampoline_type (); + TREE_ADDRESSABLE (field) = 1; + + insert_field_into_struct (get_frame_type (info), field); + + elt = xmalloc (sizeof (*elt)); + elt->old = decl; + elt->new = field; + *slot = elt; + + info->any_tramp_created = true; + } + else + field = elt ? elt->new : NULL; + + return field; +} + +/* Build or return the field within the non-local frame state that holds + the non-local goto "jmp_buf". The buffer itself is maintained by the + rtl middle-end as dynamic stack space is allocated. */ + +static tree +get_nl_goto_field (struct nesting_info *info) +{ + tree field = info->nl_goto_field; + if (!field) + { + unsigned size; + tree type; + + /* For __builtin_nonlocal_goto, we need N words. The first is the + frame pointer, the rest is for the target's stack pointer save + area. The number of words is controled by STACK_SAVEAREA_MODE; + not the best interface, but it'll do for now. */ + if (Pmode == ptr_mode) + type = ptr_type_node; + else + type = lang_hooks.types.type_for_mode (Pmode, 1); + + size = GET_MODE_SIZE (STACK_SAVEAREA_MODE (SAVE_NONLOCAL)); + size = size / GET_MODE_SIZE (Pmode); + size = size + 1; + + type = build_array_type (type, build_index_type (build_int_2 (size, 0))); + + field = make_node (FIELD_DECL); + DECL_NAME (field) = get_identifier ("__nl_goto_buf"); + TREE_TYPE (field) = type; + DECL_ALIGN (field) = TYPE_ALIGN (type); + TREE_ADDRESSABLE (field) = 1; + + insert_field_into_struct (get_frame_type (info), field); + + info->nl_goto_field = field; + } + + return field; +} + +/* Convenience routines to walk all statements of a gimple function. + + For each statement, we invoke CALLBACK via walk_tree. The passed + data is a walk_stmt_info structure. Of note here is a TSI that + points to the current statement being walked. The VAL_ONLY flag + that indicates whether the *TP being examined may be replaced + with something that matches is_gimple_val (if true) or something + slightly more complicated (if false). "Something" technically + means the common subset of is_gimple_lvalue and is_gimple_rhs, + but we never try to form anything more complicated than that, so + we don't bother checking. */ + +struct walk_stmt_info +{ + walk_tree_fn callback; + tree_stmt_iterator tsi; + struct nesting_info *info; + bool val_only; +}; + +/* A subroutine of walk_function. Iterate over all sub-statements of *TP. */ + +static void +walk_stmts (struct walk_stmt_info *wi, tree *tp) +{ + tree t = *tp; + if (!t) + return; + + switch (TREE_CODE (t)) + { + case STATEMENT_LIST: + { + tree_stmt_iterator i; + for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i)) + { + wi->tsi = i; + walk_stmts (wi, tsi_stmt_ptr (i)); + } + } + break; + + case COND_EXPR: + walk_tree (&COND_EXPR_COND (t), wi->callback, wi, NULL); + walk_stmts (wi, &COND_EXPR_THEN (t)); + walk_stmts (wi, &COND_EXPR_ELSE (t)); + break; + case CATCH_EXPR: + walk_stmts (wi, &CATCH_BODY (t)); + case EH_FILTER_EXPR: + walk_stmts (wi, &EH_FILTER_FAILURE (t)); + break; + case TRY_CATCH_EXPR: + case TRY_FINALLY_EXPR: + walk_stmts (wi, &TREE_OPERAND (t, 0)); + walk_stmts (wi, &TREE_OPERAND (t, 1)); + break; + case BIND_EXPR: + walk_stmts (wi, &BIND_EXPR_BODY (t)); + break; + + case RETURN_EXPR: + walk_stmts (wi, &TREE_OPERAND (t, 0)); + break; + + case MODIFY_EXPR: + /* The immediate arguments of a MODIFY_EXPR may use COMPONENT_REF. */ + wi->val_only = false; + walk_tree (&TREE_OPERAND (t, 0), wi->callback, wi, NULL); + wi->val_only = false; + walk_tree (&TREE_OPERAND (t, 1), wi->callback, wi, NULL); + wi->val_only = true; + break; + + default: + wi->val_only = true; + walk_tree (tp, wi->callback, wi, NULL); + break; + } +} + +/* Invoke CALLBACK on all statements of INFO->CONTEXT. */ + +static void +walk_function (walk_tree_fn callback, struct nesting_info *info) +{ + struct walk_stmt_info wi; + + memset (&wi, 0, sizeof (wi)); + wi.callback = callback; + wi.info = info; + wi.val_only = true; + + walk_stmts (&wi, &DECL_SAVED_TREE (info->context)); +} + +/* Similarly for ROOT and all functions nested underneath, depth first. */ + +static void +walk_all_functions (walk_tree_fn callback, struct nesting_info *root) +{ + do + { + if (root->inner) + walk_all_functions (callback, root->inner); + walk_function (callback, root); + root = root->next; + } + while (root); +} + + +/* Construct our local datastructure describing the function nesting + tree rooted by CGN. */ + +static struct nesting_info * +create_nesting_tree (struct cgraph_node *cgn) +{ + struct nesting_info *info = xcalloc (1, sizeof (*info)); + info->var_map = htab_create (7, var_map_hash, var_map_eq, free); + info->context = cgn->decl; + + for (cgn = cgn->nested; cgn ; cgn = cgn->next_nested) + { + struct nesting_info *sub = create_nesting_tree (cgn); + sub->outer = info; + sub->next = info->inner; + info->inner = sub; + } + + return info; +} + +/* Return an expression computing the static chain for TARGET_CONTEXT + from INFO->CONTEXT. Insert any necessary computations before TSI. */ + +static tree +get_static_chain (struct nesting_info *info, tree target_context, + tree_stmt_iterator *tsi) +{ + struct nesting_info *i; + tree x; + + if (info->context == target_context) + { + x = build_addr (info->frame_decl); + } + else + { + x = get_chain_decl (info); + + for (i = info->outer; i->context != target_context; i = i->outer) + { + tree field = get_chain_field (i); + + x = build1 (INDIRECT_REF, TREE_TYPE (TREE_TYPE (x)), x); + x = build (COMPONENT_REF, TREE_TYPE (field), x, field); + x = init_tmp_var (info, x, tsi); + } + } + + return x; +} + +/* Return an expression referencing FIELD from TARGET_CONTEXT's non-local + frame as seen from INFO->CONTEXT. Insert any necessary computations + before TSI. */ + +static tree +get_frame_field (struct nesting_info *info, tree target_context, + tree field, tree_stmt_iterator *tsi) +{ + struct nesting_info *i; + tree x; + + if (info->context == target_context) + { + /* Make sure frame_decl gets created. */ + (void) get_frame_type (info); + x = info->frame_decl; + } + else + { + x = get_chain_decl (info); + + for (i = info->outer; i->context != target_context; i = i->outer) + { + tree field = get_chain_field (i); + + x = build1 (INDIRECT_REF, TREE_TYPE (TREE_TYPE (x)), x); + x = build (COMPONENT_REF, TREE_TYPE (field), x, field); + x = init_tmp_var (info, x, tsi); + } + + x = build1 (INDIRECT_REF, TREE_TYPE (TREE_TYPE (x)), x); + } + + x = build (COMPONENT_REF, TREE_TYPE (field), x, field); + return x; +} + +/* Called via walk_function+walk_tree, rewrite all references to VAR + and PARM_DECLs that belong to outer functions. + + The rewrite will involve some number of structure accesses back up + the static chain. E.g. for a variable FOO up one nesting level it'll + be CHAIN->FOO. For two levels it'll be CHAIN->__chain->FOO. Further + indirections apply to decls for which use_pointer_in_frame is true. */ + +static tree +convert_nonlocal_reference (tree *tp, int *walk_subtrees, void *data) +{ + struct walk_stmt_info *wi = data; + struct nesting_info *info = wi->info; + tree t = *tp; + + *walk_subtrees = 0; + switch (TREE_CODE (t)) + { + case VAR_DECL: + /* Non-automatic variables are never processed. */ + if (TREE_STATIC (t) || DECL_EXTERNAL (t)) + break; + /* FALLTHRU */ + + case PARM_DECL: + if (decl_function_context (t) != info->context) + { + tree target_context = decl_function_context (t); + struct nesting_info *i; + tree x; + + for (i = info->outer; i->context != target_context; i = i->outer) + continue; + x = lookup_field_for_decl (i, t, INSERT); + x = get_frame_field (info, target_context, x, &wi->tsi); + if (use_pointer_in_frame (t)) + { + x = init_tmp_var (info, x, &wi->tsi); + x = build1 (INDIRECT_REF, TREE_TYPE (TREE_TYPE (x)), x); + } + if (wi->val_only) + x = init_tmp_var (info, x, &wi->tsi); + + *tp = x; + } + break; + + case GOTO_EXPR: + /* Don't walk non-local gotos for now. */ + if (TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL) + { + *walk_subtrees = 1; + wi->val_only = true; + } + break; + + case LABEL_DECL: + /* We're taking the address of a label from a parent function, but + this is not itself a non-local goto. Mark the label such that it + will not be deleted, much as we would with a label address in + static storage. */ + if (decl_function_context (t) != info->context) + FORCED_LABEL (t) = 1; + break; + + case ADDR_EXPR: + { + bool save_val_only = wi->val_only; + tree save_sub = TREE_OPERAND (t, 0); + + wi->val_only = false; + walk_tree (&TREE_OPERAND (t, 0), convert_nonlocal_reference, wi, NULL); + wi->val_only = true; + + if (save_sub != TREE_OPERAND (t, 0)) + { + /* If we changed anything, then TREE_INVARIANT is be wrong, + since we're no longer directly referencing a decl. */ + TREE_INVARIANT (t) = 0; + + /* If the callback converted the address argument in a context + where we only accept variables (and min_invariant, presumably), + then compute the address into a temporary. */ + if (save_val_only) + *tp = gimplify_val (wi->info, t, &wi->tsi); + } + } + break; + + case COMPONENT_REF: + case REALPART_EXPR: + case IMAGPART_EXPR: + wi->val_only = false; + walk_tree (&TREE_OPERAND (t, 0), convert_nonlocal_reference, wi, NULL); + wi->val_only = true; + break; + + case ARRAY_REF: + wi->val_only = false; + walk_tree (&TREE_OPERAND (t, 0), convert_nonlocal_reference, wi, NULL); + wi->val_only = true; + walk_tree (&TREE_OPERAND (t, 1), convert_nonlocal_reference, wi, NULL); + break; + + case BIT_FIELD_REF: + wi->val_only = false; + walk_tree (&TREE_OPERAND (t, 0), convert_nonlocal_reference, wi, NULL); + wi->val_only = true; + walk_tree (&TREE_OPERAND (t, 1), convert_nonlocal_reference, wi, NULL); + walk_tree (&TREE_OPERAND (t, 2), convert_nonlocal_reference, wi, NULL); + break; + + default: + if (!DECL_P (t) && !TYPE_P (t)) + { + *walk_subtrees = 1; + wi->val_only = true; + } + break; + } + + return NULL_TREE; +} + +/* Called via walk_function+walk_tree, rewrite all references to VAR + and PARM_DECLs that were referenced by inner nested functions. + The rewrite will be a structure reference to the local frame variable. */ + +static tree +convert_local_reference (tree *tp, int *walk_subtrees, void *data) +{ + struct walk_stmt_info *wi = data; + struct nesting_info *info = wi->info; + tree t = *tp, field, x, y; + + switch (TREE_CODE (t)) + { + case VAR_DECL: + /* Non-automatic variables are never processed. */ + if (TREE_STATIC (t) || DECL_EXTERNAL (t)) + break; + /* FALLTHRU */ + + case PARM_DECL: + if (decl_function_context (t) == info->context) + { + /* If we copied a pointer to the frame, then the original decl + is used unchanged in the parent function. */ + if (use_pointer_in_frame (t)) + break; + + /* No need to transform anything if no child references the + variable. */ + field = lookup_field_for_decl (info, t, NO_INSERT); + if (!field) + break; + + x = get_frame_field (info, info->context, field, &wi->tsi); + if (wi->val_only) + x = init_tmp_var (info, x, &wi->tsi); + *tp = x; + } + break; + + case ADDR_EXPR: + { + bool save_val_only = wi->val_only; + tree save_sub = TREE_OPERAND (t, 0); + + wi->val_only = false; + walk_tree (&TREE_OPERAND (t, 0), convert_local_reference, wi, NULL); + wi->val_only = save_val_only; + + /* If we converted anything ... */ + if (TREE_OPERAND (t, 0) != save_sub) + { + /* Then the frame decl is now addressable. */ + TREE_ADDRESSABLE (info->frame_decl) = 1; + + /* If we are in a context where we only accept values, then + compute the address into a temporary. */ + if (save_val_only) + *tp = gimplify_val (wi->info, t, &wi->tsi); + } + } + break; + + case CALL_EXPR: + *walk_subtrees = 1; + + /* Ready for some fun? We need to recognize + __builtin_stack_alloc (&x, n) + and insert + FRAME.x = &x + after that. X should have use_pointer_in_frame set. We can't + do this any earlier, since we can't meaningfully evaluate &x. */ + + x = get_callee_fndecl (t); + if (!x || DECL_BUILT_IN_CLASS (x) != BUILT_IN_NORMAL) + break; + if (DECL_FUNCTION_CODE (x) != BUILT_IN_STACK_ALLOC) + break; + t = TREE_VALUE (TREE_OPERAND (t, 1)); + if (TREE_CODE (t) != ADDR_EXPR) + abort (); + t = TREE_OPERAND (t, 0); + if (TREE_CODE (t) != VAR_DECL) + abort (); + field = lookup_field_for_decl (info, t, NO_INSERT); + if (!field) + break; + if (!use_pointer_in_frame (t)) + abort (); + + x = build_addr (t); + y = get_frame_field (info, info->context, field, &wi->tsi); + x = build (MODIFY_EXPR, void_type_node, y, x); + SET_EXPR_LOCUS (x, EXPR_LOCUS (tsi_stmt (wi->tsi))); + tsi_link_after (&wi->tsi, x, TSI_SAME_STMT); + break; + + case COMPONENT_REF: + case REALPART_EXPR: + case IMAGPART_EXPR: + wi->val_only = false; + walk_tree (&TREE_OPERAND (t, 0), convert_local_reference, wi, NULL); + wi->val_only = true; + break; + + case ARRAY_REF: + wi->val_only = false; + walk_tree (&TREE_OPERAND (t, 0), convert_local_reference, wi, NULL); + wi->val_only = true; + walk_tree (&TREE_OPERAND (t, 1), convert_local_reference, wi, NULL); + break; + + case BIT_FIELD_REF: + wi->val_only = false; + walk_tree (&TREE_OPERAND (t, 0), convert_local_reference, wi, NULL); + wi->val_only = true; + walk_tree (&TREE_OPERAND (t, 1), convert_local_reference, wi, NULL); + walk_tree (&TREE_OPERAND (t, 2), convert_local_reference, wi, NULL); + break; + + default: + if (!DECL_P (t) && !TYPE_P (t)) + { + *walk_subtrees = 1; + wi->val_only = true; + } + break; + } + + return NULL_TREE; +} + +/* Called via walk_function+walk_tree, rewrite all GOTO_EXPRs that + reference labels from outer functions. The rewrite will be a + call to __builtin_nonlocal_goto. */ + +static tree +convert_nl_goto_reference (tree *tp, int *walk_subtrees, void *data) +{ + struct walk_stmt_info *wi = data; + struct nesting_info *info = wi->info, *i; + tree t = *tp, label, new_label, target_context, x, arg, field; + struct var_map_elt *elt; + void **slot; + + *walk_subtrees = 0; + if (TREE_CODE (t) != GOTO_EXPR) + return NULL_TREE; + label = GOTO_DESTINATION (t); + if (TREE_CODE (label) != LABEL_DECL) + return NULL_TREE; + target_context = decl_function_context (label); + if (target_context == info->context) + return NULL_TREE; + + for (i = info->outer; target_context != i->context; i = i->outer) + continue; + + /* The original user label may also be use for a normal goto, therefore + we must create a new label that will actually receive the abnormal + control transfer. This new label will be marked LABEL_NONLOCAL; this + mark will trigger proper behaviour in the cfg, as well as cause the + (hairy target-specific) non-local goto receiver code to be generated + when we expand rtl. */ + new_label = create_artificial_label (); + DECL_NONLOCAL (new_label) = 1; + + /* Enter this association into var_map so that we can insert the new + label into the IL during a second pass. */ + elt = xmalloc (sizeof (*elt)); + elt->old = label; + elt->new = new_label; + slot = htab_find_slot (i->var_map, elt, INSERT); + *slot = elt; + + /* Build: __builtin_nl_goto(new_label, &chain->nl_goto_field). */ + field = get_nl_goto_field (i); + x = get_frame_field (info, target_context, field, &wi->tsi); + x = build_addr (x); + x = gimplify_val (info, x, &wi->tsi); + arg = tree_cons (NULL, x, NULL); + x = build_addr (new_label); + arg = tree_cons (NULL, x, arg); + x = implicit_built_in_decls[BUILT_IN_NONLOCAL_GOTO]; + x = build_function_call_expr (x, arg); + + SET_EXPR_LOCUS (x, EXPR_LOCUS (tsi_stmt (wi->tsi))); + *tsi_stmt_ptr (wi->tsi) = x; + + return NULL_TREE; +} + +/* Called via walk_function+walk_tree, rewrite all LABEL_EXPRs that + are referenced via nonlocal goto from a nested function. The rewrite + will involve installing a newly generated DECL_NONLOCAL label, and + (potentially) a branch around the rtl gunk that is assumed to be + attached to such a label. */ + +static tree +convert_nl_goto_receiver (tree *tp, int *walk_subtrees, void *data) +{ + struct walk_stmt_info *wi = data; + struct nesting_info *info = wi->info; + tree t = *tp, label, new_label, x; + struct var_map_elt *elt, dummy; + tree_stmt_iterator tmp_tsi; + + *walk_subtrees = 0; + if (TREE_CODE (t) != LABEL_EXPR) + return NULL_TREE; + label = LABEL_EXPR_LABEL (t); + + dummy.old = label; + elt = htab_find (info->var_map, &dummy); + if (!elt) + return NULL_TREE; + new_label = elt->new; + + /* If there's any possibility that the previous statement falls through, + then we must branch around the new non-local label. */ + tmp_tsi = wi->tsi; + tsi_prev (&tmp_tsi); + if (tsi_end_p (tmp_tsi) || block_may_fallthru (tsi_stmt (tmp_tsi))) + { + x = build1 (GOTO_EXPR, void_type_node, label); + tsi_link_before (&wi->tsi, x, TSI_SAME_STMT); + } + x = build1 (LABEL_EXPR, void_type_node, new_label); + tsi_link_before (&wi->tsi, x, TSI_SAME_STMT); + + return NULL_TREE; +} + +/* Called via walk_function+walk_tree, rewrite all references to addresses + of nested functions that require the use of trampolines. The rewrite + will involve a reference a trampoline generated for the occasion. */ + +static tree +convert_tramp_reference (tree *tp, int *walk_subtrees, void *data) +{ + struct walk_stmt_info *wi = data; + struct nesting_info *info = wi->info, *i; + tree t = *tp, decl, target_context, x, arg; + + *walk_subtrees = 0; + switch (TREE_CODE (t)) + { + case ADDR_EXPR: + /* Build + T.1 = &CHAIN->tramp; + T.2 = __builtin_adjust_trampoline (T.1); + T.3 = (func_type)T.2; + */ + + decl = TREE_OPERAND (t, 0); + if (TREE_CODE (decl) != FUNCTION_DECL) + break; + + /* Only need to process nested functions. */ + target_context = decl_function_context (decl); + if (!target_context) + break; + + /* If the nested function doesn't use a static chain, then + it doesn't need a trampoline. */ + if (DECL_NO_STATIC_CHAIN (decl)) + break; + + /* Lookup the immediate parent of the callee, as that's where + we need to insert the trampoline. */ + for (i = info; i->context != target_context; i = i->outer) + continue; + x = lookup_tramp_for_decl (i, decl, INSERT); + + /* Compute the address of the field holding the trampoline. */ + x = get_frame_field (info, target_context, x, &wi->tsi); + x = build_addr (x); + x = gimplify_val (info, x, &wi->tsi); + arg = tree_cons (NULL, x, NULL); + + /* Do machine-specific ugliness. Normally this will involve + computing extra alignment, but it can really be anything. */ + x = implicit_built_in_decls[BUILT_IN_ADJUST_TRAMPOLINE]; + x = build_function_call_expr (x, arg); + x = init_tmp_var (info, x, &wi->tsi); + + /* Cast back to the proper function type. */ + x = build1 (NOP_EXPR, TREE_TYPE (t), x); + x = init_tmp_var (info, x, &wi->tsi); + + *tp = x; + break; + + case CALL_EXPR: + /* Only walk call arguments, lest we generate trampolines for + direct calls. */ + walk_tree (&TREE_OPERAND (t, 1), convert_tramp_reference, wi, NULL); + break; + + default: + if (!DECL_P (t) && !TYPE_P (t)) + *walk_subtrees = 1; + break; + } + + return NULL_TREE; +} + +/* Called via walk_function+walk_tree, rewrite all CALL_EXPRs that + reference nested functions to make sure that the static chain is + set up properly for the call. */ + +static tree +convert_call_expr (tree *tp, int *walk_subtrees, void *data) +{ + struct walk_stmt_info *wi = data; + struct nesting_info *info = wi->info; + tree t = *tp, decl, target_context; + + *walk_subtrees = 0; + switch (TREE_CODE (t)) + { + case CALL_EXPR: + decl = get_callee_fndecl (t); + if (!decl) + break; + target_context = decl_function_context (decl); + if (target_context && !DECL_NO_STATIC_CHAIN (decl)) + TREE_OPERAND (t, 2) + = get_static_chain (info, target_context, &wi->tsi); + break; + + case RETURN_EXPR: + case MODIFY_EXPR: + /* Only return and modify may contain calls. */ + *walk_subtrees = 1; + break; + + default: + break; + } + + return NULL_TREE; +} + +/* Walk the nesting tree starting with ROOT, depth first. Convert all + trampolines and call expressions. On the way back up, determine if + a nested function actually uses its static chain; if not, remember that. */ + +static void +convert_all_function_calls (struct nesting_info *root) +{ + do + { + if (root->inner) + convert_all_function_calls (root->inner); + + walk_function (convert_tramp_reference, root); + walk_function (convert_call_expr, root); + + /* If the function does not use a static chain, then remember that. */ + if (root->outer && !root->chain_decl && !root->chain_field) + DECL_NO_STATIC_CHAIN (root->context) = 1; + else + { +#ifdef ENABLE_CHECKING + if (DECL_NO_STATIC_CHAIN (root->context)) + abort (); +#endif + } + + root = root->next; + } + while (root); +} + +/* Do "everything else" to clean up or complete state collected by the + various walking passes -- lay out the types and decls, generate code + to initialize the frame decl, store critical expressions in the + struct function for rtl to find. */ + +static void +finalize_nesting_tree_1 (struct nesting_info *root) +{ + tree stmt_list = NULL; + tree context = root->context; + struct function *sf; + + /* If we created a non-local frame type or decl, we need to lay them + out at this time. */ + if (root->frame_type) + { + layout_type (root->frame_type); + layout_decl (root->frame_decl, 0); + } + + /* If any parameters were referenced non-locally, then we need to + insert a copy. Likewise, if any variables were referenced by + pointer, we need to initialize the address. */ + if (root->any_parm_remapped) + { + tree p; + for (p = DECL_ARGUMENTS (context); p ; p = TREE_CHAIN (p)) + { + tree field, x, y; + + field = lookup_field_for_decl (root, p, NO_INSERT); + if (!field) + continue; + + if (use_pointer_in_frame (p)) + x = build_addr (p); + else + x = p; + + y = build (COMPONENT_REF, TREE_TYPE (field), + root->frame_decl, field); + x = build (MODIFY_EXPR, TREE_TYPE (field), y, x); + append_to_statement_list (x, &stmt_list); + } + } + + /* If a chain_field was created, then it needs to be initialized + from chain_decl. */ + if (root->chain_field) + { + tree x; + x = build (COMPONENT_REF, TREE_TYPE (root->chain_field), + root->frame_decl, root->chain_field); + x = build (MODIFY_EXPR, TREE_TYPE (x), x, get_chain_decl (root)); + append_to_statement_list (x, &stmt_list); + } + + /* If trampolines were created, then we need to initialize them. */ + if (root->any_tramp_created) + { + struct nesting_info *i; + for (i = root->inner; i ; i = i->next) + { + tree arg, x, field; + + field = lookup_tramp_for_decl (root, i->context, NO_INSERT); + if (!field) + continue; + + if (DECL_NO_STATIC_CHAIN (i->context)) + x = null_pointer_node; + else + x = build_addr (root->frame_decl); + arg = tree_cons (NULL, x, NULL); + + x = build_addr (i->context); + arg = tree_cons (NULL, x, arg); + + x = build (COMPONENT_REF, TREE_TYPE (field), + root->frame_decl, field); + x = build_addr (x); + arg = tree_cons (NULL, x, arg); + + x = implicit_built_in_decls[BUILT_IN_INIT_TRAMPOLINE]; + x = build_function_call_expr (x, arg); + + append_to_statement_list (x, &stmt_list); + } + } + + /* If we created initialization statements, insert them. */ + if (stmt_list) + { + annotate_all_with_locus (&stmt_list, + DECL_SOURCE_LOCATION (context)); + append_to_statement_list (BIND_EXPR_BODY (DECL_SAVED_TREE (context)), + &stmt_list); + BIND_EXPR_BODY (DECL_SAVED_TREE (context)) = stmt_list; + } + + /* If a chain_decl was created, then it needs to be registered with + struct function so that it gets initialized from the static chain + register at the beginning of the function. */ + sf = DECL_STRUCT_FUNCTION (root->context); + sf->static_chain_decl = root->chain_decl; + + /* Similarly for the non-local goto save area. */ + if (root->nl_goto_field) + { + sf->nonlocal_goto_save_area + = get_frame_field (root, context, root->nl_goto_field, NULL); + sf->has_nonlocal_label = 1; + } + + /* Make sure all new local variables get insertted into the + proper BIND_EXPR. */ + if (root->new_local_var_chain) + declare_tmp_vars (root->new_local_var_chain, + DECL_SAVED_TREE (root->context)); + + /* Dump the translated tree function. */ + dump_function (TDI_nested, root->context); +} + +static void +finalize_nesting_tree (struct nesting_info *root) +{ + do + { + if (root->inner) + finalize_nesting_tree (root->inner); + finalize_nesting_tree_1 (root); + root = root->next; + } + while (root); +} + +/* Free the data structures allocated during this pass. */ + +static void +free_nesting_tree (struct nesting_info *root) +{ + struct nesting_info *next; + do + { + if (root->inner) + free_nesting_tree (root->inner); + htab_delete (root->var_map); + next = root->next; + free (root); + root = next; + } + while (root); +} + +/* Main entry point for this pass. Process FNDECL and all of its nested + subroutines and turn them into something less tightly bound. */ + +void +lower_nested_functions (tree fndecl) +{ + struct nesting_info *root; + struct cgraph_node *cgn; + + /* If there are no nested functions, there's nothing to do. */ + cgn = cgraph_node (fndecl); + if (!cgn->nested) + return; + + root = create_nesting_tree (cgn); + walk_all_functions (convert_nonlocal_reference, root); + walk_all_functions (convert_local_reference, root); + walk_all_functions (convert_nl_goto_reference, root); + walk_all_functions (convert_nl_goto_receiver, root); + convert_all_function_calls (root); + finalize_nesting_tree (root); + free_nesting_tree (root); +} + +#include "gt-tree-nested.h" |