[Mesa-dev] [PATCH] st/mesa: remove copy-propagation pass
Marek Olšák
maraeo at gmail.com
Wed Mar 25 11:16:53 PDT 2015
Reviewed-by: Marek Olšák <marek.olsak at amd.com>
I might need to wait for other people's opinion too.
Marek
On Wed, Mar 25, 2015 at 6:34 PM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
> It's buggy and unnecessary in the presence of optimizing backends. The
> only backend that will suffer is nv30, but... meh.
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=89759
> Signed-off-by: Ilia Mirkin <imirkin at alum.mit.edu>
> ---
> src/mesa/state_tracker/st_glsl_to_tgsi.cpp | 199 -----------------------------
> 1 file changed, 199 deletions(-)
>
> diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
> index efee4b2..0402ce3 100644
> --- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
> +++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
> @@ -461,7 +461,6 @@ public:
> int get_last_temp_read(int index);
> int get_last_temp_write(int index);
>
> - void copy_propagate(void);
> int eliminate_dead_code(void);
>
> void merge_two_dsts(void);
> @@ -3757,203 +3756,6 @@ glsl_to_tgsi_visitor::get_last_temp_write(int index)
> }
>
> /*
> - * On a basic block basis, tracks available PROGRAM_TEMPORARY register
> - * channels for copy propagation and updates following instructions to
> - * use the original versions.
> - *
> - * The glsl_to_tgsi_visitor lazily produces code assuming that this pass
> - * will occur. As an example, a TXP production before this pass:
> - *
> - * 0: MOV TEMP[1], INPUT[4].xyyy;
> - * 1: MOV TEMP[1].w, INPUT[4].wwww;
> - * 2: TXP TEMP[2], TEMP[1], texture[0], 2D;
> - *
> - * and after:
> - *
> - * 0: MOV TEMP[1], INPUT[4].xyyy;
> - * 1: MOV TEMP[1].w, INPUT[4].wwww;
> - * 2: TXP TEMP[2], INPUT[4].xyyw, texture[0], 2D;
> - *
> - * which allows for dead code elimination on TEMP[1]'s writes.
> - */
> -void
> -glsl_to_tgsi_visitor::copy_propagate(void)
> -{
> - glsl_to_tgsi_instruction **acp = rzalloc_array(mem_ctx,
> - glsl_to_tgsi_instruction *,
> - this->next_temp * 4);
> - int *acp_level = rzalloc_array(mem_ctx, int, this->next_temp * 4);
> - int level = 0;
> -
> - foreach_in_list(glsl_to_tgsi_instruction, inst, &this->instructions) {
> - assert(inst->dst[0].file != PROGRAM_TEMPORARY
> - || inst->dst[0].index < this->next_temp);
> -
> - /* First, do any copy propagation possible into the src regs. */
> - for (int r = 0; r < 3; r++) {
> - glsl_to_tgsi_instruction *first = NULL;
> - bool good = true;
> - int acp_base = inst->src[r].index * 4;
> -
> - if (inst->src[r].file != PROGRAM_TEMPORARY ||
> - inst->src[r].reladdr ||
> - inst->src[r].reladdr2)
> - continue;
> -
> - /* See if we can find entries in the ACP consisting of MOVs
> - * from the same src register for all the swizzled channels
> - * of this src register reference.
> - */
> - for (int i = 0; i < 4; i++) {
> - int src_chan = GET_SWZ(inst->src[r].swizzle, i);
> - glsl_to_tgsi_instruction *copy_chan = acp[acp_base + src_chan];
> -
> - if (!copy_chan) {
> - good = false;
> - break;
> - }
> -
> - assert(acp_level[acp_base + src_chan] <= level);
> -
> - if (!first) {
> - first = copy_chan;
> - } else {
> - if (first->src[0].file != copy_chan->src[0].file ||
> - first->src[0].index != copy_chan->src[0].index ||
> - first->src[0].index2D != copy_chan->src[0].index2D) {
> - good = false;
> - break;
> - }
> - }
> - }
> -
> - if (good) {
> - /* We've now validated that we can copy-propagate to
> - * replace this src register reference. Do it.
> - */
> - inst->src[r].file = first->src[0].file;
> - inst->src[r].index = first->src[0].index;
> - inst->src[r].index2D = first->src[0].index2D;
> - inst->src[r].has_index2 = first->src[0].has_index2;
> -
> - int swizzle = 0;
> - for (int i = 0; i < 4; i++) {
> - int src_chan = GET_SWZ(inst->src[r].swizzle, i);
> - glsl_to_tgsi_instruction *copy_inst = acp[acp_base + src_chan];
> - swizzle |= (GET_SWZ(copy_inst->src[0].swizzle, src_chan) << (3 * i));
> - }
> - inst->src[r].swizzle = swizzle;
> - }
> - }
> -
> - switch (inst->op) {
> - case TGSI_OPCODE_BGNLOOP:
> - case TGSI_OPCODE_ENDLOOP:
> - /* End of a basic block, clear the ACP entirely. */
> - memset(acp, 0, sizeof(*acp) * this->next_temp * 4);
> - break;
> -
> - case TGSI_OPCODE_IF:
> - case TGSI_OPCODE_UIF:
> - ++level;
> - break;
> -
> - case TGSI_OPCODE_ENDIF:
> - case TGSI_OPCODE_ELSE:
> - /* Clear all channels written inside the block from the ACP, but
> - * leaving those that were not touched.
> - */
> - for (int r = 0; r < this->next_temp; r++) {
> - for (int c = 0; c < 4; c++) {
> - if (!acp[4 * r + c])
> - continue;
> -
> - if (acp_level[4 * r + c] >= level)
> - acp[4 * r + c] = NULL;
> - }
> - }
> - if (inst->op == TGSI_OPCODE_ENDIF)
> - --level;
> - break;
> -
> - default:
> - /* Continuing the block, clear any written channels from
> - * the ACP.
> - */
> - for (int d = 0; d < 2; d++) {
> - if (inst->dst[d].file == PROGRAM_TEMPORARY && inst->dst[d].reladdr) {
> - /* Any temporary might be written, so no copy propagation
> - * across this instruction.
> - */
> - memset(acp, 0, sizeof(*acp) * this->next_temp * 4);
> - } else if (inst->dst[d].file == PROGRAM_OUTPUT &&
> - inst->dst[d].reladdr) {
> - /* Any output might be written, so no copy propagation
> - * from outputs across this instruction.
> - */
> - for (int r = 0; r < this->next_temp; r++) {
> - for (int c = 0; c < 4; c++) {
> - if (!acp[4 * r + c])
> - continue;
> -
> - if (acp[4 * r + c]->src[0].file == PROGRAM_OUTPUT)
> - acp[4 * r + c] = NULL;
> - }
> - }
> - } else if (inst->dst[d].file == PROGRAM_TEMPORARY ||
> - inst->dst[d].file == PROGRAM_OUTPUT) {
> - /* Clear where it's used as dst. */
> - if (inst->dst[d].file == PROGRAM_TEMPORARY) {
> - for (int c = 0; c < 4; c++) {
> - if (inst->dst[d].writemask & (1 << c))
> - acp[4 * inst->dst[d].index + c] = NULL;
> - }
> - }
> -
> - /* Clear where it's used as src. */
> - for (int r = 0; r < this->next_temp; r++) {
> - for (int c = 0; c < 4; c++) {
> - if (!acp[4 * r + c])
> - continue;
> -
> - int src_chan = GET_SWZ(acp[4 * r + c]->src[0].swizzle, c);
> -
> - if (acp[4 * r + c]->src[0].file == inst->dst[d].file &&
> - acp[4 * r + c]->src[0].index == inst->dst[d].index &&
> - inst->dst[d].writemask & (1 << src_chan)) {
> - acp[4 * r + c] = NULL;
> - }
> - }
> - }
> - }
> - }
> - break;
> - }
> -
> - /* If this is a copy, add it to the ACP. */
> - if (inst->op == TGSI_OPCODE_MOV &&
> - inst->dst[0].file == PROGRAM_TEMPORARY &&
> - !(inst->dst[0].file == inst->src[0].file &&
> - inst->dst[0].index == inst->src[0].index) &&
> - !inst->dst[0].reladdr &&
> - !inst->saturate &&
> - !inst->src[0].reladdr &&
> - !inst->src[0].reladdr2 &&
> - !inst->src[0].negate) {
> - for (int i = 0; i < 4; i++) {
> - if (inst->dst[0].writemask & (1 << i)) {
> - acp[4 * inst->dst[0].index + i] = inst;
> - acp_level[4 * inst->dst[0].index + i] = level;
> - }
> - }
> - }
> - }
> -
> - ralloc_free(acp_level);
> - ralloc_free(acp);
> -}
> -
> -/*
> * On a basic block basis, tracks available PROGRAM_TEMPORARY registers for dead
> * code elimination.
> *
> @@ -5623,7 +5425,6 @@ get_mesa_program(struct gl_context *ctx,
>
> /* Perform optimizations on the instructions in the glsl_to_tgsi_visitor. */
> v->simplify_cmp();
> - v->copy_propagate();
> while (v->eliminate_dead_code());
>
> v->merge_two_dsts();
> --
> 2.0.5
>
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