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 * Default: opt_constant_folding == 1.
67 void set_opt_constant_folding(int value);
69 /** Enables/Disables algebraic simplifications.
71 * If opt_algebraic_simplification == 1 perform
72 * - algebraic simplification (a * 0 ==> 0, a or a ==> a)
73 * - simplification of tests ( !(a < b) ==> (a >= b))
74 * Default: opt_algebraic_simplification == 1.
76 void set_opt_algebraic_simplification(int value);
78 /** Enables/Disables common subexpression elimination.
80 * If opt_cse == 1 perform common subexpression elimination.
81 * Default: opt_cse == 1.
83 void set_opt_cse(int value);
85 /** Returns constant folding optimization setting. */
86 int get_opt_cse(void);
88 /** Enables/Disables global constant subexpression elimination.
90 * If opt_global_cse == 1 and opt_cse == 1 perform intra procedure
91 * constant subexpression elimination for floating nodes. Intra
92 * procedure cse gets the graph into state "floating". It is necessary
93 * to run pre/code motion to get the graph back into state "op_pin_state_pinned".
94 * right after a call to local_optimize with global cse turned on.
95 * Default: opt_global_cse == 0.
97 void set_opt_global_cse(int value);
99 /** Enables/Disables unreachable code elimination.
101 * If set, evaluate conditions of conditional branch and replace the
102 * branch with a Jmp/Bad Tuple.
104 * If opt_unreachable_code == 1 replace nodes (except Block,
105 * Phi and Tuple) with a Bad predecessor by the Bad node.
106 * Default: opt_unreachable_code == 1.
108 void set_opt_unreachable_code(int value);
110 /** Enables/Disables control flow optimizations.
112 * Performs Straightening, if simplifications and loop simplifications.
113 * Sets all separate control flow flags (control_flow_straightening,
114 * weak_simplification, strong_simplification and critical_edges).
116 void set_opt_control_flow(int value);
118 /** Enables/Disables Straightening. */
119 void set_opt_control_flow_straightening(int value);
121 /** Enables/Disables if simplifications in local optimizations. */
122 void set_opt_control_flow_weak_simplification(int value);
124 /** Enables/Disables strong if and loop simplification (in optimize_cf). */
125 void set_opt_control_flow_strong_simplification(int value);
127 /** Enable/Disable optimization of dynamic method dispatch.
129 * This flag enables/disables the optimization of dynamic method dispatch.
130 * If the flag is turned on Sel nodes can be replaced by Const nodes representing
131 * the address of a function.
133 void set_opt_dyn_meth_dispatch(int value);
134 int get_opt_dyn_meth_dispatch(void);
136 /** Enable/Disable type optimization of cast nodes.
138 * Controls the optimizations in tropt.h. Default: on.
140 void set_opt_optimize_class_casts(int value);
142 /** Restricts the behavior of cast optimization.
144 * If set, downcast are not optimized if they might be
145 * illegal as in (Super)(Sub) (new Super()). Default:
146 * 0 == not suppressed.
148 void set_opt_suppress_downcast_optimization(int value);
149 int get_opt_suppress_downcast_optimization(void);
151 /** Enable/Disable floating of fragile ops.
153 * This flags enables/disables the floating of fragile operations.
154 * If this flag is on, fragile operations which are known to NOT raise
155 * an exception can be place to other basic blocks.
156 * Otherwise they remain in the block they were created.
158 void set_opt_fragile_ops(int value);
161 * Enable/Disable Confirm node removal during local optimization.
163 void set_opt_remove_confirm(int value);
166 * Enable/Disable Null exception in Load and Store nodes only.
168 * If enabled, only Null pointer exception can occur at Load and
169 * store nodes. If it can be proved that the address input of these
170 * nodes is non-null, the exception edge can safely be removed.
171 * If disabled, other exceptions (like unaligned access, read-only memory,
174 * This flag is enabled by default.
176 void set_opt_ldst_only_null_ptr_exceptions(int value);
179 * Enable/Disable Selection based Null pointer check elimination.
181 * In languages, where all addresses are always Sel nodes, Null
182 * pointers can only occur as input to Sel nodes.
183 * If Null pointers are the only source for exceptions in Load and
184 * Store nodes (as typical in high level languages), we can eliminate
185 * exception edges from Load and Store when can prove that the Sel
186 * nodes representing the Load/Store address have non-null inputs.
187 * Enabling this flag enables this elimination.
189 * Enabling this flag is meaningless if ldst_non_null_exceptions is
192 * This flag should be set for Java style languages.
194 void set_opt_sel_based_null_check_elim(int value);
197 * Enable/Disable Global Null Pointer Test Elimination.
199 * In languages where it is illegal to dereference NULL pointer, doing
200 * so makes the pointer "valid non-null", else the program will stop
203 * This flag should be set for C style languages.
205 void set_opt_global_null_ptr_elimination(int value);
208 * Enable/Disable Automatic construction of Sync nodes during
211 * If this flags is set, sequential non-volatile Loads are automatically
212 * rearranged so that they can be executed in parallel by creating Sync nodes.
214 * This flag should be set for Java style languages.
216 void set_opt_auto_create_sync(int value);
218 /** Enable/Disable normalizations of the firm representation.
220 * This flag guards transformations that normalize the Firm representation
221 * as removing Ids and Tuples, useless Phis, replacing SymConst(id) by
222 * Const(entity) and others.
223 * The transformations guarded by this flag are not guarded by flag
225 * Many algorithms operating on Firm can not deal with constructs in
226 * the non-normalized representation.
229 * @note ATTENTION: not all such transformations are guarded by a flag.
231 void set_opt_normalize(int value);
234 * Enable/Disable ConvB() nodes with a "semantic behavior", i.e. a real
235 * operation that must be executed.
237 void set_opt_allow_conv_b(int value);
239 /** Enable/Disable precise exception context.
241 * If enabled, all exceptions form a barrier for values, as in the
250 * If precise exception handling is enabled, an exception handler see a == 1,
251 * else it might see a == 2.
252 * Enable this for languages with strict exception order like Java.
254 void set_opt_precise_exc_context(int value);
256 /** Enable/Disable Alias analysis.
258 * If enabled, memory disambiguation by alias analysis is used.
260 void set_opt_alias_analysis(int value);
262 /** Enable/Disable closed world assumption.
264 * If enabled, optimizations expect to know the "whole world", i.e. no
265 * external types or callers exist.
266 * This enables some powerful optimizations.
268 void set_opt_closed_world(int value);
271 * Save the current optimization state.
273 void save_optimization_state(optimization_state_t *state);
276 * Restore the current optimization state.
278 void restore_optimization_state(const optimization_state_t *state);
281 * Switches ALL optimizations off.
283 void all_optimizations_off(void);
286 * Possible verification modes.
288 typedef enum _firm_verification_t {
289 FIRM_VERIFICATION_OFF = 0, /**< do not verify nodes at all */
290 FIRM_VERIFICATION_ON = 1, /**< do node verification and assert on error in debug version */
291 FIRM_VERIFICATION_REPORT = 2, /**< do node verification, but report to stderr only */
292 FIRM_VERIFICATION_ERROR_ONLY = 3 /**< do node verification, but NEVER do assert nor report */
293 } firm_verification_t;
295 /** Select verification of IR nodes and types.
297 * Per default the verification is in mode NODE_VERIFICATION_ASSERT.
298 * Turn the verification off during development to check partial implementations.
300 void do_node_verification(firm_verification_t mode);