text: /*
   * Copyright (C) 2010 Marek Olšák <maraeo@gmail.com>
   *
   * All Rights Reserved.
   *
   * Permission is hereby granted, free of charge, to any person obtaining
   * a copy of this software and associated documentation files (the
   * "Software"), to deal in the Software without restriction, including
   * without limitation the rights to use, copy, modify, merge, publish,
   * distribute, sublicense, and/or sell copies of the Software, and to
   * permit persons to whom the Software is furnished to do so, subject to
   * the following conditions:
   *
   * The above copyright notice and this permission notice (including the
   * next paragraph) shall be included in all copies or substantial
   * portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
   * IN NO EVENT SHALL THE COPYRIGHT OWNER(S) AND/OR ITS SUPPLIERS BE
   * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
   * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   *
   */
  
  #include <stdlib.h>
  #include "radeon_remove_constants.h"
  #include "radeon_dataflow.h"
  
  struct mark_used_data {
  	unsigned char * const_used;
  	unsigned * has_rel_addr;
  };
  
  static void remap_regs(void * userdata, struct rc_instruction * inst,
  			rc_register_file * pfile, unsigned int * pindex)
  {
  	unsigned *inv_remap_table = userdata;
  
  	if (*pfile == RC_FILE_CONSTANT) {
  		*pindex = inv_remap_table[*pindex];
  	}
  }
  
  static void mark_used(void * userdata, struct rc_instruction * inst,
  						struct rc_src_register * src)
  {
  	struct mark_used_data * d = userdata;
  
  	if (src->File == RC_FILE_CONSTANT) {
  		if (src->RelAddr) {
  			*d->has_rel_addr = 1;
  		} else {
  			d->const_used[src->Index] = 1;
  		}
  	}
  }
  
  void rc_remove_unused_constants(struct radeon_compiler *c, void *user)
  {
  	unsigned **out_remap_table = (unsigned**)user;
  	unsigned char *const_used;
  	unsigned *remap_table;
  	unsigned *inv_remap_table;
  	unsigned has_rel_addr = 0;
  	unsigned is_identity = 1;
  	unsigned are_externals_remapped = 0;
  	struct rc_constant *constants = c->Program.Constants.Constants;
  	struct mark_used_data d;
  	unsigned new_count;
  
  	if (!c->Program.Constants.Count) {
  		*out_remap_table = NULL;
  		return;
  	}
  
  	const_used = malloc(c->Program.Constants.Count);
  	memset(const_used, 0, c->Program.Constants.Count);
  
  	d.const_used = const_used;
  	d.has_rel_addr = &has_rel_addr;
  
  	/* Pass 1: Mark used constants. */
  	for (struct rc_instruction *inst = c->Program.Instructions.Next;
  	     inst != &c->Program.Instructions; inst = inst->Next) {
  		rc_for_all_reads_src(inst, mark_used, &d);
  	}
  
  	/* Pass 2: If there is relative addressing or dead constant elimination
  	 * is disabled, mark all externals as used. */
  	if (has_rel_addr || !c->remove_unused_constants) {
  		for (unsigned i = 0; i < c->Program.Constants.Count; i++)
  			if (constants[i].Type == RC_CONSTANT_EXTERNAL)
  				const_used[i] = 1;
  	}
  
  	/* Pass 3: Make the remapping table and remap constants.
  	 * This pass removes unused constants simply by overwriting them by other constants. */
  	remap_table = malloc(c->Program.Constants.Count * sizeof(unsigned));
  	inv_remap_table = malloc(c->Program.Constants.Count * sizeof(unsigned));
  	new_count = 0;
  
  	for (unsigned i = 0; i < c->Program.Constants.Count; i++) {
  		if (const_used[i]) {
  			remap_table[new_count] = i;
  			inv_remap_table[i] = new_count;
  
  			if (i != new_count) {
  				if (constants[i].Type == RC_CONSTANT_EXTERNAL)
  					are_externals_remapped = 1;
  
  				constants[new_count] = constants[i];
  				is_identity = 0;
  			}
  			new_count++;
  		}
  	}
  
  	/*  is_identity ==> new_count == old_count
  	 * !is_identity ==> new_count <  old_count */
  	assert( is_identity || new_count <  c->Program.Constants.Count);
  	assert(!((has_rel_addr || !c->remove_unused_constants) && are_externals_remapped));
  
  	/* Pass 4: Redirect reads of all constants to their new locations. */
  	if (!is_identity) {
  		for (struct rc_instruction *inst = c->Program.Instructions.Next;
  		     inst != &c->Program.Instructions; inst = inst->Next) {
  			rc_remap_registers(inst, remap_regs, inv_remap_table);
  		}
  	}
  
  	/* Set the new constant count. Note that new_count may be less than
  	 * Count even though the remapping function is identity. In that case,
  	 * the constants have been removed at the end of the array. */
  	c->Program.Constants.Count = new_count;
  
  	if (are_externals_remapped) {
  		*out_remap_table = remap_table;
  	} else {
  		*out_remap_table = NULL;
  		free(remap_table);
  	}
  
  	free(const_used);
  	free(inv_remap_table);
  
  	if (c->Debug & RC_DBG_LOG)
  		rc_constants_print(&c->Program.Constants);
  }
  