From 2ef81372dccc102d95b3dcec22b42406e1b55af9 Mon Sep 17 00:00:00 2001 From: Kenneth Graunke Date: Fri, 9 Aug 2013 17:53:05 -0700 Subject: [PATCH] i965/fs: Separate the updating of liveout/livein. To compute the actual liveout/livein data flow values, we start with some initial values and apply a fixed-point algorithm until they settle. Previously, we iterated through all blocks, updating both liveout and livein together in one pass. This is awkward, since computing livein for a block requires knowing liveout for all parent blocks. Not all of those parent blocks may have been processed yet. This patch separates the two. First, we update liveout for all blocks. At iteration N of the fixed-point algorithm, this uses livein values from iteration N-1. Secondly, we update livein for all blocks. At step N, this uses the liveout information we just computed (in step N). This ensures each computation has a consistent picture of the data, rather than seeing an random mix of data from steps N-1 and N depending on the order of the blocks in the CFG data structure. Signed-off-by: Kenneth Graunke Reviewed-by: Paul Berry --- src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp b/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp index 055444d4c99..144a43f85ac 100644 --- a/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp +++ b/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp @@ -167,6 +167,7 @@ fs_copy_prop_dataflow::run() do { progress = false; + /* Update liveout for all blocks. */ for (int b = 0; b < cfg->num_blocks; b++) { for (int i = 0; i < bitset_words; i++) { BITSET_WORD new_liveout = (bd[b].livein[i] & @@ -176,10 +177,14 @@ fs_copy_prop_dataflow::run() bd[b].liveout[i] |= new_liveout; progress = true; } + } + } - /* Update livein: if it's live at the end of all parents, it's - * live at our start. - */ + /* Update livein for all blocks. If a copy is live out of all parent + * blocks, it's live coming in to this block. + */ + for (int b = 0; b < cfg->num_blocks; b++) { + for (int i = 0; i < bitset_words; i++) { BITSET_WORD new_livein = ~bd[b].livein[i]; foreach_list(block_node, &cfg->blocks[b]->parents) { bblock_link *link = (bblock_link *)block_node; -- 2.30.2