2 * cfold.c: Constant folding support
5 * Paolo Molaro (lupus@ximian.com)
6 * Dietmar Maurer (dietmar@ximian.com)
8 * (C) 2003 Ximian, Inc. http://www.ximian.com
13 mono_is_power_of_two (guint32 val
)
17 for (i
= 0, j
= 1, k
= 0xfffffffe; i
< 32; ++i
, j
= j
<< 1, k
= k
<< 1) {
21 if (i
== 32 || val
& k
)
26 #define FOLD_BINOP(name,op) \
28 if (inst->inst_i0->opcode != OP_ICONST) \
30 if (inst->inst_i1->opcode == OP_ICONST) { \
31 inst->opcode = OP_ICONST; \
32 inst->inst_c0 = inst->inst_i0->inst_c0 op inst->inst_i1->inst_c0; \
37 * We try to put constants on the left side of a commutative operation
38 * because it reduces register pressure and it matches the usual cpu
39 * instructions with immediates.
41 #define FOLD_BINOPCOMM(name,op) \
43 if (inst->inst_i0->opcode == OP_ICONST) {\
44 if (inst->inst_i1->opcode == OP_ICONST) { \
45 inst->opcode = OP_ICONST; \
46 inst->inst_c0 = inst->inst_i0->inst_c0 op inst->inst_i1->inst_c0; \
49 MonoInst *tmp = inst->inst_i0; \
50 inst->inst_i0 = inst->inst_i1; \
51 inst->inst_i1 = tmp; \
54 if (inst->inst_i1->opcode == OP_ICONST && inst->opcode == CEE_ADD) { \
55 if (inst->inst_i1->inst_c0 == 0) { \
56 *inst = *(inst->inst_i0); \
60 if (inst->inst_i1->opcode == OP_ICONST && inst->opcode == CEE_MUL) { \
62 if (inst->inst_i1->inst_c0 == 1) { \
63 *inst = *(inst->inst_i0); \
65 } else if (inst->inst_i1->inst_c0 == -1) { \
66 inst->opcode = CEE_NEG; \
69 power2 = mono_is_power_of_two (inst->inst_i1->inst_c0); \
70 if (power2 < 0) return; \
71 inst->opcode = CEE_SHL; \
72 inst->inst_i1->inst_c0 = power2; \
77 #define MYGINT32_MAX 2147483647
78 #define G_MININT32 (-MYGINT32_MAX -1)
82 * We can't let this cause a division by zero exception since the division
83 * might not be executed during runtime.
85 #define FOLD_BINOPZ(name,op,cast) \
87 if (inst->inst_i1->opcode == OP_ICONST && inst->opcode == CEE_REM_UN && inst->inst_i1->inst_c0 == 2) { \
88 inst->opcode = CEE_AND; \
89 inst->inst_i1->inst_c0 = 1; \
92 if (inst->inst_i1->opcode == OP_ICONST) { \
93 if (!inst->inst_i1->inst_c0) return; \
94 if (inst->inst_i0->opcode == OP_ICONST) { \
95 if ((inst->inst_i0->inst_c0 == G_MININT32) && (inst->inst_i1->inst_c0 == -1)) \
97 inst->inst_c0 = (cast)inst->inst_i0->inst_c0 op (cast)inst->inst_i1->inst_c0; \
98 inst->opcode = OP_ICONST; \
100 int power2 = mono_is_power_of_two (inst->inst_i1->inst_c0); \
101 if (power2 < 0) return; \
102 if (inst->opcode == CEE_REM_UN) { \
103 inst->opcode = CEE_AND; \
104 inst->inst_i1->inst_c0 = (1 << power2) - 1; \
105 } else if (inst->opcode == CEE_DIV_UN) { \
106 inst->opcode = CEE_SHR_UN; \
107 inst->inst_i1->inst_c0 = power2; \
113 #define FOLD_BINOPA(name,op,cast) \
115 if (inst->inst_i0->opcode != OP_ICONST) \
117 if (inst->inst_i1->opcode == OP_ICONST) { \
118 inst->opcode = OP_ICONST; \
119 inst->inst_c0 = (cast)inst->inst_i0->inst_c0 op (cast)inst->inst_i1->inst_c0; \
123 #define FOLD_CXX(name,op,cast) \
125 if (inst->inst_i0->opcode != OP_COMPARE) \
127 if (inst->inst_i0->inst_i0->opcode != OP_ICONST) \
129 if (inst->inst_i0->inst_i1->opcode == OP_ICONST) { \
130 inst->opcode = OP_ICONST; \
131 inst->inst_c0 = (cast)inst->inst_i0->inst_i0->inst_c0 op (cast)inst->inst_i0->inst_i1->inst_c0; \
135 #define FOLD_UNOP(name,op) \
137 if (inst->inst_i0->opcode == OP_ICONST) { \
138 inst->opcode = OP_ICONST; \
139 inst->inst_c0 = op inst->inst_i0->inst_c0; \
140 } else if (inst->inst_i0->opcode == OP_I8CONST) { \
141 inst->opcode = OP_I8CONST; \
142 inst->inst_l = op inst->inst_i0->inst_l; \
145 #define FOLD_BRBINOP(name,op,cast) \
147 if (inst->inst_i0->opcode != OP_COMPARE) \
149 if (inst->inst_i0->inst_i0->opcode != OP_ICONST) \
151 if (inst->inst_i0->inst_i1->opcode == OP_ICONST) { \
152 if ((cast)inst->inst_i0->inst_i0->inst_c0 op (cast)inst->inst_i0->inst_i1->inst_c0) \
153 inst->opcode = CEE_BR; \
155 inst->opcode = CEE_NOP; \
160 * Helper function to do constant expression evaluation.
161 * We do constant folding of integers only, FP stuff is much more tricky,
162 * int64 probably not worth it.
165 mono_constant_fold_inst (MonoInst
*inst
, gpointer data
)
167 switch (inst
->opcode
) {
169 /* FIXME: the CEE_B* don't contain operands, need to use the OP_COMPARE instruction */
170 /*FOLD_BRBINOP (CEE_BEQ,==,gint32)
171 FOLD_BRBINOP (CEE_BGE,>=,gint32)
172 FOLD_BRBINOP (CEE_BGT,>,gint32)
173 FOLD_BRBINOP (CEE_BLE,<=,gint32)
174 FOLD_BRBINOP (CEE_BLT,<,gint32)
175 FOLD_BRBINOP (CEE_BNE_UN,!=,guint32)
176 FOLD_BRBINOP (CEE_BGE_UN,>=,guint32)
177 FOLD_BRBINOP (CEE_BGT_UN,>,guint32)
178 FOLD_BRBINOP (CEE_BLE_UN,<=,guint32)
179 FOLD_BRBINOP (CEE_BLT_UN,<,guint32)*/
181 FOLD_BINOPCOMM (CEE_MUL
,*)
183 FOLD_BINOPCOMM (CEE_ADD
,+)
184 FOLD_BINOP (CEE_SUB
,-)
185 FOLD_BINOPZ (CEE_DIV
,/,gint32
)
186 FOLD_BINOPZ (CEE_DIV_UN
,/,guint32
)
187 FOLD_BINOPZ (CEE_REM
,%,gint32
)
188 FOLD_BINOPZ (CEE_REM_UN
,%,guint32
)
189 FOLD_BINOPCOMM (CEE_AND
,&)
190 FOLD_BINOPCOMM (CEE_OR
,|)
191 FOLD_BINOPCOMM (CEE_XOR
,^)
192 FOLD_BINOP (CEE_SHL
,<<)
193 FOLD_BINOP (CEE_SHR
,>>)
195 if (inst
->inst_i0
->opcode
!= OP_ICONST
)
197 if (inst
->inst_i1
->opcode
== OP_ICONST
) {
198 inst
->opcode
= OP_ICONST
;
199 inst
->inst_c0
= (guint32
)inst
->inst_i0
->inst_c0
>> (guint32
)inst
->inst_i1
->inst_c0
;
202 FOLD_UNOP (CEE_NEG
,-)
203 FOLD_UNOP (CEE_NOT
,~)
204 FOLD_CXX (OP_CEQ
,==,gint32
)
205 FOLD_CXX (OP_CGT
,>,gint32
)
206 FOLD_CXX (OP_CGT_UN
,>,guint32
)
207 FOLD_CXX (OP_CLT
,<,gint32
)
208 FOLD_CXX (OP_CLT_UN
,<,guint32
)
210 if (inst
->inst_i0
->opcode
== OP_ICONST
) {
211 inst
->opcode
= OP_I8CONST
;
212 inst
->inst_l
= inst
->inst_i0
->inst_c0
;
217 if (inst
->inst_i0
->opcode
== OP_ICONST
) {
218 inst
->opcode
= OP_ICONST
;
219 inst
->inst_c0
= inst
->inst_i0
->inst_c0
;
220 } else if (inst
->inst_i0
->opcode
== CEE_LDIND_I
) {
221 *inst
= *inst
->inst_i0
;
224 /* we should be able to handle isinst and castclass as well */
230 * *ovf* opcodes? I'ts slow and hard to do in C.
231 * switch can be replaced by a simple jump
233 #if SIZEOF_VOID_P == 4
235 if ((inst
->inst_left
->type
== STACK_I4
) || (inst
->inst_left
->type
== STACK_PTR
)) {
236 *inst
= *inst
->inst_left
;
246 mono_constant_fold (MonoCompile
*cfg
)
250 for (bb
= cfg
->bb_entry
; bb
; bb
= bb
->next_bb
) {
252 for (ins
= bb
->code
; ins
; ins
= ins
->next
)
253 mono_inst_foreach (ins
, mono_constant_fold_inst
, NULL
);
258 * If the arguments to the cond branch are constants, eval and
259 * return BRANCH_NOT_TAKEN for not taken, BRANCH_TAKEN for taken,
260 * BRANCH_UNDEF otherwise.
261 * If this code is changed to handle also non-const values, make sure
262 * side effects are handled in optimize_branches() in mini.c, by
263 * inserting pop instructions.
266 mono_eval_cond_branch (MonoInst
*ins
)
268 MonoInst
*left
, *right
;
269 /* FIXME: handle also 64 bit ints */
270 left
= ins
->inst_left
->inst_left
;
271 if (left
->opcode
!= OP_ICONST
&& left
->opcode
!= OP_PCONST
)
273 right
= ins
->inst_left
->inst_right
;
274 if (right
->opcode
!= OP_ICONST
&& right
->opcode
!= OP_PCONST
)
276 switch (ins
->opcode
) {
278 if (left
->inst_c0
== right
->inst_c0
)
280 return BRANCH_NOT_TAKEN
;
282 if (left
->inst_c0
>= right
->inst_c0
)
284 return BRANCH_NOT_TAKEN
;
286 if (left
->inst_c0
> right
->inst_c0
)
288 return BRANCH_NOT_TAKEN
;
290 if (left
->inst_c0
<= right
->inst_c0
)
292 return BRANCH_NOT_TAKEN
;
294 if (left
->inst_c0
< right
->inst_c0
)
296 return BRANCH_NOT_TAKEN
;
298 if ((gsize
)left
->inst_c0
!= (gsize
)right
->inst_c0
)
300 return BRANCH_NOT_TAKEN
;
302 if ((gsize
)left
->inst_c0
>= (gsize
)right
->inst_c0
)
304 return BRANCH_NOT_TAKEN
;
306 if ((gsize
)left
->inst_c0
> (gsize
)right
->inst_c0
)
308 return BRANCH_NOT_TAKEN
;
310 if ((gsize
)left
->inst_c0
<= (gsize
)right
->inst_c0
)
312 return BRANCH_NOT_TAKEN
;
314 if ((gsize
)left
->inst_c0
< (gsize
)right
->inst_c0
)
316 return BRANCH_NOT_TAKEN
;