On Sat, Feb 13, 2016 at 9:14 PM, Jason Ekstrand <ja...@jlekstrand.net> wrote:
> ---
> src/compiler/nir/nir.c | 63
> ++++++++++++++++++++++++++++++++++++++++++++++++++
> src/compiler/nir/nir.h | 2 ++
> 2 files changed, 65 insertions(+)
>
> diff --git a/src/compiler/nir/nir.c b/src/compiler/nir/nir.c
> index cd78475..468065a 100644
> --- a/src/compiler/nir/nir.c
> +++ b/src/compiler/nir/nir.c
> @@ -716,6 +716,69 @@ nir_cf_node_get_function(nir_cf_node *node)
> return nir_cf_node_as_function(node);
> }
>
> +/* Reduces a cursor by trying to convert everything to after and trying to
> + * go up to block granularity when possible.
> + */
> +static nir_cursor
> +reduce_cursor(nir_cursor cursor)
> +{
> + switch (cursor.option) {
> + case nir_cursor_before_block:
> + if (exec_list_is_empty(&cursor.block->instr_list)) {
> + /* Empty block. After is as good as before. */
> + cursor.option = nir_cursor_after_block;
> + } else {
> + /* Try to switch to after the previous block if there is one.
> + * (This isn't likely, but it can happen.)
> + */
> + nir_cf_node *prev_node = nir_cf_node_prev(&cursor.block->cf_node);
> + if (prev_node && prev_node->type == nir_cf_node_block) {
How can the current node and the previous node both be blocks? It's an
invariant of the control-flow modification code that no two blocks
ever wind up next to each other.
> + cursor.block = nir_cf_node_as_block(prev_node);
> + cursor.option = nir_cursor_after_block;
> + }
> + }
> + return cursor;
> +
> + case nir_cursor_after_block:
> + return cursor;
> +
> + case nir_cursor_before_instr: {
> + nir_instr *prev_instr = nir_instr_prev(cursor.instr);
> + if (prev_instr) {
> + /* Before this instruction is after the previous */
> + cursor.instr = prev_instr;
> + cursor.option = nir_cursor_after_instr;
> + } else {
> + /* No previous instruction. Switch to before block */
> + cursor.block = cursor.instr->block;
> + cursor.option = nir_cursor_before_block;
> + }
> + return reduce_cursor(cursor);
> + }
> +
> + case nir_cursor_after_instr:
> + if (nir_instr_next(cursor.instr) == NULL) {
> + /* This is the last instruction, switch to after block */
> + cursor.option = nir_cursor_after_block;
> + cursor.block = cursor.instr->block;
> + }
> + return cursor;
> +
> + default:
> + unreachable("Inavlid cursor option");
> + }
> +}
> +
> +bool
> +nir_cursors_equal(nir_cursor a, nir_cursor b)
> +{
> + /* Reduced cursors should be unique */
> + a = reduce_cursor(a);
> + b = reduce_cursor(b);
> +
> + return a.block == b.block && a.option == b.option;
> +}
> +
> static bool
> add_use_cb(nir_src *src, void *state)
> {
> diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
> index 4c6c22f..c856b83 100644
> --- a/src/compiler/nir/nir.h
> +++ b/src/compiler/nir/nir.h
> @@ -1803,6 +1803,8 @@ typedef struct {
> };
> } nir_cursor;
>
> +bool nir_cursors_equal(nir_cursor a, nir_cursor b);
> +
> static inline nir_cursor
> nir_before_block(nir_block *block)
> {
> --
> 2.5.0.400.gff86faf
>
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