[Mesa-dev] [PATCH v2 2/5] radeonsi/gfx9: always wrap GS and TCS in an if-block (v2)
Nicolai Hähnle
nhaehnle at gmail.com
Wed Jul 26 11:56:12 UTC 2017
From: Nicolai Hähnle <nicolai.haehnle at amd.com>
With merged ESGS shaders, the GS part of a wave may be empty, and the
hardware gets confused if any GS messages are sent from that wave. Since
S_SENDMSG is executed even when EXEC = 0, we have to wrap even
non-monolithic GS shaders in an if-block, so that the entire shader and
hence the S_SENDMSG instructions are skipped in empty waves.
This change is not required for TCS/HS, but applying it there as well
simplifies the logic a bit.
Fixes GL45-CTS.geometry_shader.rendering.rendering.*
v2: ensure that the TCS epilog doesn't run for non-existing patches
Cc: mesa-stable at lists.freedesktop.org
---
src/gallium/drivers/radeonsi/si_shader.c | 109 +++++++++++++++-------
src/gallium/drivers/radeonsi/si_shader_internal.h | 3 +
2 files changed, 79 insertions(+), 33 deletions(-)
diff --git a/src/gallium/drivers/radeonsi/si_shader.c b/src/gallium/drivers/radeonsi/si_shader.c
index a153cb7..9376d90 100644
--- a/src/gallium/drivers/radeonsi/si_shader.c
+++ b/src/gallium/drivers/radeonsi/si_shader.c
@@ -175,6 +175,20 @@ unsigned si_shader_io_get_unique_index(unsigned semantic_name, unsigned index)
}
/**
+ * Helper function that builds an LLVM IR PHI node and immediately adds
+ * incoming edges.
+ */
+static LLVMValueRef
+build_phi(struct ac_llvm_context *ctx, LLVMTypeRef type,
+ unsigned count_incoming, LLVMValueRef *values,
+ LLVMBasicBlockRef *blocks)
+{
+ LLVMValueRef phi = LLVMBuildPhi(ctx->builder, type, "");
+ LLVMAddIncoming(phi, values, blocks, count_incoming);
+ return phi;
+}
+
+/**
* Get the value of a shader input parameter and extract a bitfield.
*/
static LLVMValueRef unpack_param(struct si_shader_context *ctx,
@@ -2698,6 +2712,7 @@ si_insert_input_ptr_as_2xi32(struct si_shader_context *ctx, LLVMValueRef ret,
static void si_llvm_emit_tcs_epilogue(struct lp_build_tgsi_context *bld_base)
{
struct si_shader_context *ctx = si_shader_context(bld_base);
+ LLVMBuilderRef builder = ctx->gallivm.builder;
LLVMValueRef rel_patch_id, invocation_id, tf_lds_offset;
si_copy_tcs_inputs(bld_base);
@@ -2706,8 +2721,29 @@ static void si_llvm_emit_tcs_epilogue(struct lp_build_tgsi_context *bld_base)
invocation_id = unpack_param(ctx, ctx->param_tcs_rel_ids, 8, 5);
tf_lds_offset = get_tcs_out_current_patch_data_offset(ctx);
+ if (ctx->screen->b.chip_class >= GFX9) {
+ LLVMBasicBlockRef blocks[2] = {
+ LLVMGetInsertBlock(builder),
+ ctx->merged_wrap_if_state.entry_block
+ };
+ LLVMValueRef values[2];
+
+ lp_build_endif(&ctx->merged_wrap_if_state);
+
+ values[0] = rel_patch_id;
+ values[1] = LLVMGetUndef(ctx->i32);
+ rel_patch_id = build_phi(&ctx->ac, ctx->i32, 2, values, blocks);
+
+ values[0] = tf_lds_offset;
+ values[1] = LLVMGetUndef(ctx->i32);
+ tf_lds_offset = build_phi(&ctx->ac, ctx->i32, 2, values, blocks);
+
+ values[0] = invocation_id;
+ values[1] = ctx->i32_1; /* cause the epilog to skip threads */
+ invocation_id = build_phi(&ctx->ac, ctx->i32, 2, values, blocks);
+ }
+
/* Return epilog parameters from this function. */
- LLVMBuilderRef builder = ctx->gallivm.builder;
LLVMValueRef ret = ctx->return_value;
unsigned vgpr;
@@ -2935,6 +2971,9 @@ static void si_llvm_emit_gs_epilogue(struct lp_build_tgsi_context *bld_base)
ac_build_sendmsg(&ctx->ac, AC_SENDMSG_GS_OP_NOP | AC_SENDMSG_GS_DONE,
si_get_gs_wave_id(ctx));
+
+ if (ctx->screen->b.chip_class >= GFX9)
+ lp_build_endif(&ctx->merged_wrap_if_state);
}
static void si_llvm_emit_vs_epilogue(struct lp_build_tgsi_context *bld_base)
@@ -5502,14 +5541,20 @@ static bool si_compile_tgsi_main(struct si_shader_context *ctx,
preload_ring_buffers(ctx);
/* For GFX9 merged shaders:
- * - Set EXEC. If the prolog is present, set EXEC there instead.
+ * - Set EXEC for the first shader. If the prolog is present, set
+ * EXEC there instead.
* - Add a barrier before the second shader.
+ * - In the second shader, reset EXEC to ~0 and wrap the main part in
+ * an if-statement. This is required for correctness in geometry
+ * shaders, to ensure that empty GS waves do not send GS_EMIT and
+ * GS_CUT messages.
*
- * The same thing for monolithic shaders is done in
- * si_build_wrapper_function.
+ * For monolithic merged shaders, the first shader is wrapped in an
+ * if-block together with its prolog in si_build_wrapper_function.
*/
- if (ctx->screen->b.chip_class >= GFX9 && !is_monolithic) {
- if (sel->info.num_instructions > 1 && /* not empty shader */
+ if (ctx->screen->b.chip_class >= GFX9) {
+ if (!is_monolithic &&
+ sel->info.num_instructions > 1 && /* not empty shader */
(shader->key.as_es || shader->key.as_ls) &&
(ctx->type == PIPE_SHADER_TESS_EVAL ||
(ctx->type == PIPE_SHADER_VERTEX &&
@@ -5518,9 +5563,19 @@ static bool si_compile_tgsi_main(struct si_shader_context *ctx,
ctx->param_merged_wave_info, 0);
} else if (ctx->type == PIPE_SHADER_TESS_CTRL ||
ctx->type == PIPE_SHADER_GEOMETRY) {
- si_init_exec_from_input(ctx,
- ctx->param_merged_wave_info, 8);
+ if (!is_monolithic)
+ si_init_exec_full_mask(ctx);
+
+ /* The barrier must execute for all shaders in a
+ * threadgroup.
+ */
si_llvm_emit_barrier(NULL, bld_base, NULL);
+
+ LLVMValueRef num_threads = unpack_param(ctx, ctx->param_merged_wave_info, 8, 8);
+ LLVMValueRef ena =
+ LLVMBuildICmp(ctx->ac.builder, LLVMIntULT,
+ ac_get_thread_id(&ctx->ac), num_threads, "");
+ lp_build_if(&ctx->merged_wrap_if_state, &ctx->gallivm, ena);
}
}
@@ -5991,15 +6046,9 @@ static void si_build_wrapper_function(struct si_shader_context *ctx,
/* Merged shaders are executed conditionally depending
* on the number of enabled threads passed in the input SGPRs. */
- if (is_merged_shader(ctx->shader) &&
- (part == 0 || part == next_shader_first_part)) {
+ if (is_merged_shader(ctx->shader) && part == 0) {
LLVMValueRef ena, count = initial[3];
- /* The thread count for the 2nd shader is at bit-offset 8. */
- if (part == next_shader_first_part) {
- count = LLVMBuildLShr(builder, count,
- LLVMConstInt(ctx->i32, 8, 0), "");
- }
count = LLVMBuildAnd(builder, count,
LLVMConstInt(ctx->i32, 0x7f, 0), "");
ena = LLVMBuildICmp(builder, LLVMIntULT,
@@ -6056,26 +6105,20 @@ static void si_build_wrapper_function(struct si_shader_context *ctx,
ret = LLVMBuildCall(builder, parts[part], in, num_params, "");
if (is_merged_shader(ctx->shader) &&
- (part + 1 == next_shader_first_part ||
- part + 1 == num_parts)) {
+ part + 1 == next_shader_first_part) {
lp_build_endif(&if_state);
- if (part + 1 == next_shader_first_part) {
- /* A barrier is required between 2 merged shaders. */
- si_llvm_emit_barrier(NULL, &ctx->bld_base, NULL);
-
- /* The second half of the merged shader should use
- * the inputs from the toplevel (wrapper) function,
- * not the return value from the last call.
- *
- * That's because the last call was executed condi-
- * tionally, so we can't consume it in the main
- * block.
- */
- memcpy(out, initial, sizeof(initial));
- num_out = initial_num_out;
- num_out_sgpr = initial_num_out_sgpr;
- }
+ /* The second half of the merged shader should use
+ * the inputs from the toplevel (wrapper) function,
+ * not the return value from the last call.
+ *
+ * That's because the last call was executed condi-
+ * tionally, so we can't consume it in the main
+ * block.
+ */
+ memcpy(out, initial, sizeof(initial));
+ num_out = initial_num_out;
+ num_out_sgpr = initial_num_out_sgpr;
continue;
}
diff --git a/src/gallium/drivers/radeonsi/si_shader_internal.h b/src/gallium/drivers/radeonsi/si_shader_internal.h
index 6e86e0b..6b98bca 100644
--- a/src/gallium/drivers/radeonsi/si_shader_internal.h
+++ b/src/gallium/drivers/radeonsi/si_shader_internal.h
@@ -25,6 +25,7 @@
#define SI_SHADER_PRIVATE_H
#include "si_shader.h"
+#include "gallivm/lp_bld_flow.h"
#include "gallivm/lp_bld_init.h"
#include "gallivm/lp_bld_tgsi.h"
#include "tgsi/tgsi_parse.h"
@@ -105,6 +106,8 @@ struct si_shader_context {
unsigned flow_depth;
unsigned flow_depth_max;
+ struct lp_build_if_state merged_wrap_if_state;
+
struct tgsi_array_info *temp_arrays;
LLVMValueRef *temp_array_allocas;
--
2.9.3
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