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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 * File name: ir/lower/lower_calls.h
23 * Purpose: lowering of Calls with compound parameters
24 * Author: Michael Beck
27 * Copyright: (c) 1998-2005 Universität Karlsruhe
33 * Lowering of Calls with compound return types.
35 * @author Michael Beck
37 #ifndef _LOWER_CALLS_H_
38 #define _LOWER_CALLS_H_
41 * A type telling where to add hidden parameters.
43 typedef enum add_hidden_params {
44 ADD_HIDDEN_ALWAYS_IN_FRONT = 0, /**< always add hidden parameters in front (default). */
45 ADD_HIDDEN_ALWAYS_LAST = 1, /**< always add hidden parameters last, did not work for variadic functions. */
46 ADD_HIDDEN_SMART = 2 /**< add hidden parameters last for non-variadic and first for variadic functions. */
50 * Additional flags for the lowering.
53 LF_NONE = 0, /**< no additional flags */
54 LF_COMPOUND_PARAM = 1, /**< lower calls with compound parameters */
55 LF_COMPOUND_RETURN = 2, /**< lower calls with compound returns */
56 LF_RETURN_HIDDEN = 4, /**< return the hidden address instead of void */
57 LF_SMALL_CMP_IN_REGS = 8 /**< return small compound values in registers */
60 /** Maximum number of registers that can be used to return compound values. */
61 #define MAX_REGISTER_RET_VAL 2
64 * A struct containing all control parameters for
65 * lower_compound_ret_calls().
68 int def_ptr_alignment; /**< Default alignment for data pointer. */
69 unsigned flags; /**< A bitmask of enum lowering_flags. */
70 add_hidden hidden_params; /**< Where to add hidden parameters. */
73 * A function returning a pointer type for a given type.
74 * If this pointer is NULL, a new pointer type is always created.
76 ir_type *(*find_pointer_type)(ir_type *e_type, ir_mode *mode, int alignment);
79 * If the LF_SMALL_CMP_IN_REGS flag is set, this function will be called
80 * to decide, whether a compound value should be returned in registers.
81 * This function must return the number of used registers and fill in the modes
82 * of the registers to use. Up to MAX_REGISTER_RET_VAL registers can be used.
84 int (*ret_compound_in_regs)(ir_type *compound_tp, ir_mode **modes);
88 * Lower calls with compound parameter and return types.
89 * This function does the following transformations:
91 * If LF_COMPOUND_PARAM is set:
93 * - Copy compound parameters to a new location on the callers
94 * stack and transmit the address of this new location
96 * If LF_COMPOUND_RETURN is set:
98 * - Adds a new (hidden) pointer parameter for
99 * any return compound type. The return type is replaced by void
100 * or if LOWERING_FLAGS_RETURN_HIDDEN is set by the address.
102 * - Use of the hidden parameters in the function code.
104 * - Change all calls to functions with compound return
105 * by providing space for the hidden parameter on the callers
108 * - Replace a possible block copy after the function call.
112 * - Changes the types of methods and calls to the lowered ones
114 * - lower all method types of existing entities
116 * In pseudo-code, the following transformation is done:
119 struct x ret = func(a, b);
128 * If the function returns only one possible result, the copy-on-return
129 * optimization is done, ie.
138 * is transformed into
141 void func(struct x *ret, a) {
146 * @param params A structure containing the control parameter for this
149 * During the transformation, pointer types must be created or reused.
150 * The caller can provide params->find_pointer_type for this task to
151 * reduce the number of created pointer types.
152 * If params->find_pointer_type is NULL, new pointer types
153 * are always created automatically.
155 void lower_calls_with_compounds(const lower_params_t *params);
157 #endif /* _LOWER_CALLS_H_ */