2 * Copyright (C) 1995-2008 University of Karlsruhe. All right reserved.
4 * This file is part of libFirm.
6 * This file may be distributed and/or modified under the terms of the
7 * GNU General Public License version 2 as published by the Free Software
8 * Foundation and appearing in the file LICENSE.GPL included in the
9 * packaging of this file.
11 * Licensees holding valid libFirm Professional Edition licenses may use
12 * this file in accordance with the libFirm Commercial License.
13 * Agreement provided with the Software.
15 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
16 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * @brief Flags to control optimizations.
23 * @author Christian Schaefer, Goetz Lindenmaier, Michael Beck
26 * Flags to customize the behavior of libfirm.
28 * There are the following groups of flags:
29 * 1. Optimization flags.
30 * a) There is a flag, 'optimize' to turn on/off all optimizations.
31 * b) There are flags for each individual optimization. Some flags turns
32 * transformations in several algorithms on/off.
33 * 2. Normalization flags.
34 * These flags steer transformations of the ir that improve it, as removing
35 * dump Phi nodes (one predecessor, all predecessors are equal ...), Ids, Tuples ...
37 * a) Flags to steer the level of the information.
38 * b) Flags to steer in which phase information should be dumped.
39 * 4. Verification flag
40 * This one controls the behavior of node and type verifications
42 #ifndef FIRM_IR_IRFLAG_H
43 #define FIRM_IR_IRFLAG_H
45 #include "firm_types.h"
48 * A container type to load/restore all optimizations
50 typedef unsigned optimization_state_t;
53 * This function enables/disables optimizations globally.
55 * If optimize == 0 no optimizations are performed at all.
56 * Default: optimize == 1.
58 void set_optimize(int value);
59 int get_optimize(void);
61 /** Enables/Disables constant folding optimization.
63 * If opt_constant_folding == 1 perform
64 * - constant expression evaluation (2 + 5 ==> 7, 3 < 2 ==> false)
65 * - algebraic simplification (a * 0 ==> 0, a or a ==> a)
66 * - simplification of tests ( !(a < b) ==> (a >= b))
67 * Default: opt_constant_folding == 1.
69 void set_opt_constant_folding(int value);
71 /** Enables/Disables common subexpression elimination.
73 * If opt_cse == 1 perform common subexpression elimination.
74 * Default: opt_cse == 1.
76 void set_opt_cse(int value);
78 /** Returns constant folding optimization setting. */
79 int get_opt_cse(void);
81 /** Enables/Disables global constant subexpression elimination.
83 * If opt_global_cse == 1 and opt_cse == 1 perform intra procedure
84 * constant subexpression elimination for floating nodes. Intra
85 * procedure cse gets the graph into state "floating". It is necessary
86 * to run pre/code motion to get the graph back into state "op_pin_state_pinned".
87 * right after a call to local_optimize with global cse turned on.
88 * Default: opt_global_cse == 0.
90 void set_opt_global_cse(int value);
92 /** Enables/Disables strength reduction.
94 * If opt_strength_red == 1 perform strength reduction.
97 * Default: opt_strength_red = 1;
99 void set_opt_strength_red(int value);
101 /** Enables/Disables unreachable code elimination.
103 * If set, evaluate conditions of conditional branch and replace the
104 * branch with a Jmp/Bad Tuple.
106 * If opt_unreachable_code == 1 replace nodes (except Block,
107 * Phi and Tuple) with a Bad predecessor by the Bad node.
108 * Default: opt_unreachable_code == 1.
110 void set_opt_unreachable_code(int value);
112 /** Enables/Disables control flow optimizations.
114 * Performs Straightening, if simplifications and loop simplifications.
115 * Sets all separate control flow flags (control_flow_straightening,
116 * weak_simplification, strong_simplification and critical_edges).
118 void set_opt_control_flow(int value);
120 /** Enables/Disables Straightening. */
121 void set_opt_control_flow_straightening(int value);
123 /** Enables/Disables if simplifications in local optimizations. */
124 void set_opt_control_flow_weak_simplification(int value);
126 /** Enables/Disables strong if and loop simplification (in optimize_cf). */
127 void set_opt_control_flow_strong_simplification(int value);
129 /** Enable/Disable optimization of dynamic method dispatch.
131 * This flag enables/disables the optimization of dynamic method dispatch.
132 * If the flag is turned on Sel nodes can be replaced by Const nodes representing
133 * the address of a function.
135 void set_opt_dyn_meth_dispatch(int value);
136 int get_opt_dyn_meth_dispatch(void);
138 /** Enable/Disable type optimization of cast nodes.
140 * Controls the optimizations in tropt.h. Default: on.
142 void set_opt_optimize_class_casts(int value);
144 /** Restricts the behavior of cast optimization.
146 * If set, downcast are not optimized if they might be
147 * illegal as in (Super)(Sub) (new Super()). Default:
148 * 0 == not suppressed.
150 void set_opt_suppress_downcast_optimization(int value);
151 int get_opt_suppress_downcast_optimization(void);
153 /** Enable/Disable floating of fragile ops.
155 * This flags enables/disables the floating of fragile operations.
156 * If this flag is on, fragile operations which are known to NOT raise
157 * an exception can be place to other basic blocks.
158 * Otherwise they remain in the block they were created.
160 void set_opt_fragile_ops(int value);
163 * Enable/Disable Confirm node removal during local optimization.
165 void set_opt_remove_confirm(int value);
168 * Enable/Disable scalar replacement optimization.
170 void set_opt_scalar_replacement(int value);
173 * Enable/Disable Null exception in Load and Store nodes only.
175 * If enabled, only Null pointer exception can occur at Load and
176 * store nodes. If it can be proved that the address input of these
177 * nodes is non-null, the exception edge can safely be removed.
178 * If disabled, other exceptions (like unaligned access, read-only memory,
181 * This flag is enabled by default.
183 void set_opt_ldst_only_null_ptr_exceptions(int value);
186 * Enable/Disable Selection based Null pointer check elimination.
188 * In languages, where all addresses are always Sel nodes, Null
189 * pointers can only occur as input to Sel nodes.
190 * If Null pointers are the only source for exceptions in Load and
191 * Store nodes (as typical in high level languages), we can eliminate
192 * exception edges from Load and Store when can prove that the Sel
193 * nodes representing the Load/Store address have non-null inputs.
194 * Enabling this flag enables this elimination.
196 * Enabling this flag is meaningless if ldst_non_null_exceptions is
199 * This flags should be set for Java style languages.
201 void set_opt_sel_based_null_check_elim(int value);
204 * Enable/Disable Automatic construction of Sync nodes during
207 * If this flags is set, sequential non-volatile Loads are automatically
208 * rearranged so that they can be executed in parallel by creating Sync nodes.
210 * This flags should be set for Java style languages.
212 void set_opt_auto_create_sync(int value);
214 /** Enable/Disable normalizations of the firm representation.
216 * This flag guards transformations that normalize the Firm representation
217 * as removing Ids and Tuples, useless Phis, replacing SymConst(id) by
218 * Const(entity) and others.
219 * The transformations guarded by this flag are not guarded by flag
221 * Many algorithms operating on Firm can not deal with constructs in
222 * the non-normalized representation.
225 * @note ATTENTION: not all such transformations are guarded by a flag.
227 void set_opt_normalize(int value);
229 /** Enable/Disable precise exception context.
231 * If enabled, all exceptions form a barrier for values, as in the
240 * If precise exception handling is enabled, an exception handler see a == 1,
241 * else it might see a == 2.
242 * Enable this for languages with strict exception order like Java.
244 void set_opt_precise_exc_context(int value);
246 /** Enable/Disable Alias analysis.
248 * If enabled, memory disambiguation by alias analysis is used.
250 void set_opt_alias_analysis(int value);
252 /** Enable/Disable closed world assumption.
254 * If enabled, optimizations expect to know the "whole world", i.e. no
255 * external types or callers exist.
256 * This enables some powerful optimizations.
258 void set_opt_closed_world(int value);
261 * Save the current optimization state.
263 void save_optimization_state(optimization_state_t *state);
266 * Restore the current optimization state.
268 void restore_optimization_state(const optimization_state_t *state);
271 * Switches ALL optimizations off.
273 void all_optimizations_off(void);
276 * Possible verification modes.
278 typedef enum _firm_verification_t {
279 FIRM_VERIFICATION_OFF = 0, /**< do not verify nodes at all */
280 FIRM_VERIFICATION_ON = 1, /**< do node verification and assert on error in debug version */
281 FIRM_VERIFICATION_REPORT = 2, /**< do node verification, but report to stderr only */
282 FIRM_VERIFICATION_ERROR_ONLY = 3 /**< do node verification, but NEVER do assert nor report */
283 } firm_verification_t;
285 /** Select verification of IR nodes and types.
287 * Per default the verification is in mode NODE_VERIFICATION_ASSERT.
288 * Turn the verification off during development to check partial implementations.
290 void do_node_verification(firm_verification_t mode);