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nir: add rewrite_phi_predecessor_blocks() helper

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This will also be used by the if merge pass in the following commit.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
This commit is contained in:
Timothy Arceri 2018-11-21 10:04:24 +11:00
parent 5122fbc4ba
commit 19cafe8084
1 changed files with 31 additions and 20 deletions
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51
src/compiler/nir/nir_opt_if.c
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@ -335,6 +335,35 @@ opt_if_loop_last_continue(nir_loop *loop)
return true;
}
/* Walk all the phis in the block immediately following the if statement and
* swap the blocks.
*/
static void
rewrite_phi_predecessor_blocks(nir_if *nif,
nir_block *old_then_block,
nir_block *old_else_block,
nir_block *new_then_block,
nir_block *new_else_block)
{
nir_block *after_if_block =
nir_cf_node_as_block(nir_cf_node_next(&nif->cf_node));
nir_foreach_instr(instr, after_if_block) {
if (instr->type != nir_instr_type_phi)
continue;
nir_phi_instr *phi = nir_instr_as_phi(instr);
foreach_list_typed(nir_phi_src, src, node, &phi->srcs) {
if (src->pred == old_then_block) {
src->pred = new_then_block;
} else if (src->pred == old_else_block) {
src->pred = new_else_block;
}
}
}
}
/**
* This optimization turns:
*
@ -379,26 +408,8 @@ opt_if_simplification(nir_builder *b, nir_if *nif)
nir_block *then_block = nir_if_last_then_block(nif);
nir_block *else_block = nir_if_last_else_block(nif);
/* Walk all the phis in the block immediately following the if statement and
* swap the blocks.
*/
nir_block *after_if_block =
nir_cf_node_as_block(nir_cf_node_next(&nif->cf_node));
nir_foreach_instr(instr, after_if_block) {
if (instr->type != nir_instr_type_phi)
continue;
nir_phi_instr *phi = nir_instr_as_phi(instr);
foreach_list_typed(nir_phi_src, src, node, &phi->srcs) {
if (src->pred == else_block) {
src->pred = then_block;
} else if (src->pred == then_block) {
src->pred = else_block;
}
}
}
rewrite_phi_predecessor_blocks(nif, then_block, else_block, else_block,
then_block);
/* Finally, move the else block to the then block. */
nir_cf_list tmp;