[Mesa-dev] [PATCH v3 5/7] i965: Add a NIR analysis pass for determining when a boolean resolve is needed
Jason Ekstrand
jason at jlekstrand.net
Fri Mar 20 14:23:07 PDT 2015
v2: Fix the spelling of analyze and re-arrange code for better readability
as per Connor's comments.
v3: Make the naming of things more consistent and add a pile of comments
---
src/mesa/drivers/dri/i965/Makefile.sources | 2 +
src/mesa/drivers/dri/i965/brw_nir.h | 78 ++++++
.../dri/i965/brw_nir_analyze_boolean_resolves.c | 275 +++++++++++++++++++++
3 files changed, 355 insertions(+)
create mode 100644 src/mesa/drivers/dri/i965/brw_nir.h
create mode 100644 src/mesa/drivers/dri/i965/brw_nir_analyze_boolean_resolves.c
diff --git a/src/mesa/drivers/dri/i965/Makefile.sources b/src/mesa/drivers/dri/i965/Makefile.sources
index c69441b..3a3df70 100644
--- a/src/mesa/drivers/dri/i965/Makefile.sources
+++ b/src/mesa/drivers/dri/i965/Makefile.sources
@@ -73,6 +73,8 @@ i965_FILES = \
brw_meta_util.h \
brw_misc_state.c \
brw_multisample_state.h \
+ brw_nir.h \
+ brw_nir_analyze_boolean_resolves.c \
brw_object_purgeable.c \
brw_packed_float.c \
brw_performance_monitor.c \
diff --git a/src/mesa/drivers/dri/i965/brw_nir.h b/src/mesa/drivers/dri/i965/brw_nir.h
new file mode 100644
index 0000000..27782a3
--- /dev/null
+++ b/src/mesa/drivers/dri/i965/brw_nir.h
@@ -0,0 +1,78 @@
+/*
+ * Copyright © 2015 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#pragma once
+
+#include "glsl/nir/nir.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Flags set in the instr->pass_flags field by i965 analysis passes */
+enum {
+ BRW_NIR_NON_BOOLEAN = 0x0,
+
+ /* Indicates that the given instruction's destination is a boolean
+ * value but that it needs to be resolved before it can be used.
+ * On Gen <= 5, CMP instructions return a 32-bit value where the bottom
+ * bit represents the actual true/false value of the compare and the top
+ * 31 bits are undefined. In order to use this value, we have to do a
+ * "resolve" operation by replacing the value of the CMP with -(x & 1)
+ * to sign-extend the bottom bit to 0/~0.
+ */
+ BRW_NIR_BOOLEAN_NEEDS_RESOLVE = 0x1,
+
+ /* Indicates that the given instruction's destination is a boolean
+ * value that has intentionally been left unresolved. Not all boolean
+ * values need to be resolved immediately. For instance, if we have
+ *
+ * CMP r1 r2 r3
+ * CMP r4 r5 r6
+ * AND r7 r1 r4
+ *
+ * We don't have to resolve the result of the two CMP instructions
+ * immediately because the AND still does an AND of the bottom bits.
+ * Instead, we can save ourselves instructions by delaying the resolve
+ * until after the AND. The result of the two CMP instructions is left
+ * as BRW_NIR_BOOLEAN_UNRESOLVED.
+ */
+ BRW_NIR_BOOLEAN_UNRESOLVED = 0x2,
+
+ /* Indicates a that the given instruction's destination is a boolean
+ * value that does not need a resolve. For instance, if you AND two
+ * values that are BRW_NIR_BOOLEAN_NEEDS_RESOLVE then we know that both
+ * values will be 0/~0 before we get them and the result of the AND is
+ * also guaranteed to be 0/~0 and does not need a resolve.
+ */
+ BRW_NIR_BOOLEAN_NO_RESOLVE = 0x3,
+
+ /* A mask to mask the boolean status values off of instr->pass_flags */
+ BRW_NIR_BOOLEAN_MASK = 0x3,
+};
+
+void brw_nir_analyze_boolean_resolves(nir_shader *nir);
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/src/mesa/drivers/dri/i965/brw_nir_analyze_boolean_resolves.c b/src/mesa/drivers/dri/i965/brw_nir_analyze_boolean_resolves.c
new file mode 100644
index 0000000..e893a65
--- /dev/null
+++ b/src/mesa/drivers/dri/i965/brw_nir_analyze_boolean_resolves.c
@@ -0,0 +1,275 @@
+/*
+ * Copyright © 2015 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ * Authors:
+ * Jason Ekstrand <jason at jlekstrand.net>
+ */
+
+#include "brw_nir.h"
+
+/*
+ * This file implements an analysis pass that determines when we have to do
+ * a boolean resolve on Gen <= 5. Instructions that need a boolean resolve
+ * will have the booleans portion of the instr->pass_flags field set to
+ * BRW_NIR_BOOLEAN_NEEDS_RESOLVE.
+ */
+
+
+/** Returns the resolve status for the given source
+ *
+ * If the source has a parent instruction then the resolve status is the
+ * status of the parent instruction. If the source does not have a parent
+ * instruction then we don't know so we return NON_BOOLEAN.
+ */
+static uint8_t
+get_resolve_status_for_src(nir_src *src)
+{
+ nir_instr *src_instr;
+ if (src->is_ssa) {
+ src_instr = src->ssa->parent_instr;
+ } else {
+ src_instr = src->reg.reg->parent_instr;
+ }
+
+ if (src_instr) {
+ uint8_t resolve_status = src_instr->pass_flags & BRW_NIR_BOOLEAN_MASK;
+
+ /* If the source instruction needs resolve, then from the perspective
+ * of the user, it's a true boolean.
+ */
+ if (resolve_status == BRW_NIR_BOOLEAN_NEEDS_RESOLVE)
+ resolve_status = BRW_NIR_BOOLEAN_NO_RESOLVE;
+ return resolve_status;
+ } else {
+ return BRW_NIR_NON_BOOLEAN;
+ }
+}
+
+/** Marks the given source as needing a resolve
+ *
+ * If the given source corresponds to an unresolved boolean it marks it as
+ * needing a resolve. Otherwise, we leave it alone.
+ */
+static bool
+src_mark_needs_resolve(nir_src *src, void *void_state)
+{
+ nir_instr *src_instr;
+ if (src->is_ssa) {
+ src_instr = src->ssa->parent_instr;
+ } else {
+ src_instr = src->reg.reg->parent_instr;
+ }
+
+ if (src_instr) {
+ uint8_t resolve_status = src_instr->pass_flags & BRW_NIR_BOOLEAN_MASK;
+
+ /* If the source instruction is unresolved, then mark it as needing
+ * to be resolved.
+ */
+ if (resolve_status == BRW_NIR_BOOLEAN_UNRESOLVED) {
+ src_instr->pass_flags &= ~BRW_NIR_BOOLEAN_MASK;
+ src_instr->pass_flags |= BRW_NIR_BOOLEAN_NEEDS_RESOLVE;
+ }
+
+ }
+
+ return true;
+}
+
+static bool
+analyze_boolean_resolves_block(nir_block *block, void *void_state)
+{
+ nir_foreach_instr(block, instr) {
+ switch (instr->type) {
+ case nir_instr_type_alu: {
+ /* For ALU instructions, the resolve status is handled in a
+ * three-step process.
+ *
+ * 1) Look at the instruction type and sources and determine if it
+ * can be left unresolved.
+ *
+ * 2) Look at the destination and see if we have to resolve
+ * anyway. (This is the case if this instruction is not the
+ * only instruction writing to a given register.)
+ *
+ * 3) If the instruction has a resolve status other than
+ * BOOL_UNRESOLVED or BOOL_NEEDS_RESOLVE then we walk through
+ * the sources and ensure that they are also resolved. This
+ * ensures that we don't end up with any stray unresolved
+ * booleans going into ADDs or something like that.
+ */
+
+ uint8_t resolve_status;
+ nir_alu_instr *alu = nir_instr_as_alu(instr);
+ switch (alu->op) {
+ case nir_op_flt:
+ case nir_op_ilt:
+ case nir_op_ult:
+ case nir_op_fge:
+ case nir_op_ige:
+ case nir_op_uge:
+ case nir_op_feq:
+ case nir_op_ieq:
+ case nir_op_fne:
+ case nir_op_ine:
+ case nir_op_f2b:
+ case nir_op_i2b:
+ /* This instruction will turn into a CMP when we actually emit
+ * so the result will have to be resolved before it can be used.
+ */
+ resolve_status = BRW_NIR_BOOLEAN_UNRESOLVED;
+
+ /* Even though the destination is allowed to be left unresolved,
+ * the sources are treated as regular integers or floats so
+ * they need to be resolved.
+ */
+ nir_foreach_src(instr, src_mark_needs_resolve, NULL);
+ break;
+
+ case nir_op_imov:
+ case nir_op_inot:
+ if (alu->dest.write_mask == 1) {
+ /* This is a single-source instruction. Just copy the
+ * resolve status from the source.
+ */
+ resolve_status = get_resolve_status_for_src(&alu->src[0].src);
+ } else {
+ /* Vector versions will be assumed to be non-boolean. */
+ resolve_status = BRW_NIR_NON_BOOLEAN;
+ }
+ break;
+
+ case nir_op_iand:
+ case nir_op_ior:
+ case nir_op_ixor: {
+ assert(alu->dest.write_mask == 1);
+
+ uint8_t src0_status = get_resolve_status_for_src(&alu->src[0].src);
+ uint8_t src1_status = get_resolve_status_for_src(&alu->src[1].src);
+
+ if (src0_status == src1_status) {
+ resolve_status = src0_status;
+ } else if (src0_status == BRW_NIR_NON_BOOLEAN ||
+ src1_status == BRW_NIR_NON_BOOLEAN) {
+ /* If one of the sources is a non-boolean then the whole
+ * thing is a non-boolean.
+ */
+ resolve_status = BRW_NIR_NON_BOOLEAN;
+ } else {
+ /* At this point one of them is a true boolean and one is a
+ * boolean that needs a resolve. We could either resolve the
+ * unresolved source or we could resolve here. If we resolve
+ * the unresolved source then we get two resolves for the price
+ * of one. Just set this one to BOOLEAN_NO_RESOLVE and we'll
+ * let the code below force a resolve on the unresolved source.
+ */
+ resolve_status = BRW_NIR_BOOLEAN_NO_RESOLVE;
+ }
+ break;
+ }
+
+ default:
+ resolve_status = BRW_NIR_NON_BOOLEAN;
+ }
+
+ /* If the destination is SSA-like, go ahead allow unresolved booleans.
+ * If the destination register doesn't have a well-defined parent_instr
+ * we need to resolve immediately.
+ */
+ if (alu->dest.dest.reg.reg->parent_instr == NULL &&
+ resolve_status == BRW_NIR_BOOLEAN_UNRESOLVED) {
+ resolve_status = BRW_NIR_BOOLEAN_NEEDS_RESOLVE;
+ }
+
+ instr->pass_flags = (instr->pass_flags & ~BRW_NIR_BOOLEAN_MASK) |
+ resolve_status;
+
+ /* Finally, resolve sources if it's needed */
+ switch (resolve_status) {
+ case BRW_NIR_BOOLEAN_NEEDS_RESOLVE:
+ case BRW_NIR_BOOLEAN_UNRESOLVED:
+ /* This instruction is either unresolved or we're doing the
+ * resolve here; leave the sources alone.
+ */
+ break;
+
+ case BRW_NIR_BOOLEAN_NO_RESOLVE:
+ case BRW_NIR_NON_BOOLEAN:
+ nir_foreach_src(instr, src_mark_needs_resolve, NULL);
+ break;
+
+ default:
+ unreachable("Invalid boolean flag");
+ }
+
+ break;
+ }
+
+ case nir_instr_type_load_const: {
+ nir_load_const_instr *load = nir_instr_as_load_const(instr);
+
+ /* For load_const instructions, it's a boolean exactly when it holds
+ * one of the values NIR_TRUE or NIR_FALSE.
+ *
+ * Since load_const instructions don't have any sources, we don't
+ * have to worry about resolving them.
+ */
+ instr->pass_flags &= ~BRW_NIR_BOOLEAN_MASK;
+ if (load->value.u[0] == NIR_TRUE || load->value.u[0] == NIR_FALSE) {
+ instr->pass_flags |= BRW_NIR_BOOLEAN_NO_RESOLVE;
+ } else {
+ instr->pass_flags |= BRW_NIR_NON_BOOLEAN;
+ }
+ continue;
+ }
+
+ default:
+ /* Everything else is an unknown non-boolean value and needs to
+ * have all sources resolved.
+ */
+ instr->pass_flags = (instr->pass_flags & ~BRW_NIR_BOOLEAN_MASK) |
+ BRW_NIR_NON_BOOLEAN;
+ nir_foreach_src(instr, src_mark_needs_resolve, NULL);
+ continue;
+ }
+ }
+
+ nir_if *following_if = nir_block_get_following_if(block);
+ if (following_if)
+ src_mark_needs_resolve(&following_if->condition, NULL);
+
+ return true;
+}
+
+static void
+analyze_boolean_resolves_impl(nir_function_impl *impl)
+{
+ nir_foreach_block(impl, analyze_boolean_resolves_block, NULL);
+}
+
+void
+brw_nir_analyze_boolean_resolves(nir_shader *shader)
+{
+ nir_foreach_overload(shader, overload)
+ if (overload->impl)
+ analyze_boolean_resolves_impl(overload->impl);
+}
--
2.3.3
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