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      1 /*
      2  * Copyright (C) 2010 Marek Olk <maraeo (at) gmail.com>
      3  *
      4  * All Rights Reserved.
      5  *
      6  * Permission is hereby granted, free of charge, to any person obtaining
      7  * a copy of this software and associated documentation files (the
      8  * "Software"), to deal in the Software without restriction, including
      9  * without limitation the rights to use, copy, modify, merge, publish,
     10  * distribute, sublicense, and/or sell copies of the Software, and to
     11  * permit persons to whom the Software is furnished to do so, subject to
     12  * the following conditions:
     13  *
     14  * The above copyright notice and this permission notice (including the
     15  * next paragraph) shall be included in all copies or substantial
     16  * portions of the Software.
     17  *
     18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
     19  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
     20  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
     21  * IN NO EVENT SHALL THE COPYRIGHT OWNER(S) AND/OR ITS SUPPLIERS BE
     22  * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
     23  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
     24  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
     25  *
     26  */
     27 
     28 #include <stdlib.h>
     29 #include "radeon_remove_constants.h"
     30 #include "radeon_dataflow.h"
     31 
     32 struct mark_used_data {
     33 	unsigned char * const_used;
     34 	unsigned * has_rel_addr;
     35 };
     36 
     37 static void remap_regs(void * userdata, struct rc_instruction * inst,
     38 			rc_register_file * pfile, unsigned int * pindex)
     39 {
     40 	unsigned *inv_remap_table = userdata;
     41 
     42 	if (*pfile == RC_FILE_CONSTANT) {
     43 		*pindex = inv_remap_table[*pindex];
     44 	}
     45 }
     46 
     47 static void mark_used(void * userdata, struct rc_instruction * inst,
     48 						struct rc_src_register * src)
     49 {
     50 	struct mark_used_data * d = userdata;
     51 
     52 	if (src->File == RC_FILE_CONSTANT) {
     53 		if (src->RelAddr) {
     54 			*d->has_rel_addr = 1;
     55 		} else {
     56 			d->const_used[src->Index] = 1;
     57 		}
     58 	}
     59 }
     60 
     61 void rc_remove_unused_constants(struct radeon_compiler *c, void *user)
     62 {
     63 	unsigned **out_remap_table = (unsigned**)user;
     64 	unsigned char *const_used;
     65 	unsigned *remap_table;
     66 	unsigned *inv_remap_table;
     67 	unsigned has_rel_addr = 0;
     68 	unsigned is_identity = 1;
     69 	unsigned are_externals_remapped = 0;
     70 	struct rc_constant *constants = c->Program.Constants.Constants;
     71 	struct mark_used_data d;
     72 	unsigned new_count;
     73 
     74 	if (!c->Program.Constants.Count) {
     75 		*out_remap_table = NULL;
     76 		return;
     77 	}
     78 
     79 	const_used = malloc(c->Program.Constants.Count);
     80 	memset(const_used, 0, c->Program.Constants.Count);
     81 
     82 	d.const_used = const_used;
     83 	d.has_rel_addr = &has_rel_addr;
     84 
     85 	/* Pass 1: Mark used constants. */
     86 	for (struct rc_instruction *inst = c->Program.Instructions.Next;
     87 	     inst != &c->Program.Instructions; inst = inst->Next) {
     88 		rc_for_all_reads_src(inst, mark_used, &d);
     89 	}
     90 
     91 	/* Pass 2: If there is relative addressing or dead constant elimination
     92 	 * is disabled, mark all externals as used. */
     93 	if (has_rel_addr || !c->remove_unused_constants) {
     94 		for (unsigned i = 0; i < c->Program.Constants.Count; i++)
     95 			if (constants[i].Type == RC_CONSTANT_EXTERNAL)
     96 				const_used[i] = 1;
     97 	}
     98 
     99 	/* Pass 3: Make the remapping table and remap constants.
    100 	 * This pass removes unused constants simply by overwriting them by other constants. */
    101 	remap_table = malloc(c->Program.Constants.Count * sizeof(unsigned));
    102 	inv_remap_table = malloc(c->Program.Constants.Count * sizeof(unsigned));
    103 	new_count = 0;
    104 
    105 	for (unsigned i = 0; i < c->Program.Constants.Count; i++) {
    106 		if (const_used[i]) {
    107 			remap_table[new_count] = i;
    108 			inv_remap_table[i] = new_count;
    109 
    110 			if (i != new_count) {
    111 				if (constants[i].Type == RC_CONSTANT_EXTERNAL)
    112 					are_externals_remapped = 1;
    113 
    114 				constants[new_count] = constants[i];
    115 				is_identity = 0;
    116 			}
    117 			new_count++;
    118 		}
    119 	}
    120 
    121 	/*  is_identity ==> new_count == old_count
    122 	 * !is_identity ==> new_count <  old_count */
    123 	assert( is_identity || new_count <  c->Program.Constants.Count);
    124 	assert(!((has_rel_addr || !c->remove_unused_constants) && are_externals_remapped));
    125 
    126 	/* Pass 4: Redirect reads of all constants to their new locations. */
    127 	if (!is_identity) {
    128 		for (struct rc_instruction *inst = c->Program.Instructions.Next;
    129 		     inst != &c->Program.Instructions; inst = inst->Next) {
    130 			rc_remap_registers(inst, remap_regs, inv_remap_table);
    131 		}
    132 	}
    133 
    134 	/* Set the new constant count. Note that new_count may be less than
    135 	 * Count even though the remapping function is identity. In that case,
    136 	 * the constants have been removed at the end of the array. */
    137 	c->Program.Constants.Count = new_count;
    138 
    139 	if (are_externals_remapped) {
    140 		*out_remap_table = remap_table;
    141 	} else {
    142 		*out_remap_table = NULL;
    143 		free(remap_table);
    144 	}
    145 
    146 	free(const_used);
    147 	free(inv_remap_table);
    148 
    149 	if (c->Debug & RC_DBG_LOG)
    150 		rc_constants_print(&c->Program.Constants);
    151 }
    152