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i965/cfg: Make DO instruction begin a basic block.

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The DO instruction doesn't exist on Gen6+. Since before this commit, DO
always ended a basic block, if it also happened to start one (e.g., a
while loop inside an if statement) the block containing only the DO
would actually contain no hardware instructions.

Pre-Gen6's WHILE instructions jumps to the instruction following the DO,
so strictly speaking we won't be modeling that properly, but I claim
there is actually no functional difference.

This will simplify an upcoming change where we want to mark the first
hardware instruction in the loop as beginning a block, and the last
instruction before the loop as ending one.

Reviewed-by: Eric Anholt <eric@anholt.net>
This commit is contained in:
Matt Turner
2014-05-17 11:53:45 -07:00
parent 04ce3be401
commit dd0e1c3aff
1 changed files with 12 additions and 9 deletions
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src/mesa/drivers/dri/i965/brw_cfg.cpp
+12 -9
View File
@@ -98,7 +98,7 @@ cfg_t::cfg_t(exec_list *instructions)
bblock_t *cur_if = NULL; /**< BB ending with IF. */
bblock_t *cur_else = NULL; /**< BB ending with ELSE. */
bblock_t *cur_endif = NULL; /**< BB starting with ENDIF. */
bblock_t *cur_do = NULL; /**< BB ending with DO. */
bblock_t *cur_do = NULL; /**< BB starting with DO. */
bblock_t *cur_while = NULL; /**< BB immediately following WHILE. */
exec_list if_stack, else_stack, do_stack, while_stack;
bblock_t *next;
@@ -205,15 +205,18 @@ cfg_t::cfg_t(exec_list *instructions)
*/
cur_while = new_block();
/* Set up our immediately following block, full of "then"
* instructions.
*/
next = new_block();
next->start = (backend_instruction *)inst->next;
cur->add_successor(mem_ctx, next);
cur_do = next;
if (cur->start == inst) {
/* New block was just created; use it. */
cur_do = cur;
} else {
cur_do = new_block();
cur_do->start = inst;
set_next_block(&cur, next, ip);
cur->end = (backend_instruction *)inst->prev;
cur->add_successor(mem_ctx, cur_do);
set_next_block(&cur, cur_do, ip - 1);
}
break;
case BRW_OPCODE_CONTINUE: