[Mesa-dev] [PATCH 01/10] i965: use nir_lower_indirect_derefs() for GLSL Gen7+

[Timothy Arceri]

This moves the nir_lower_indirect_derefs() call into
brw_preprocess_nir() so thats is called by both OpenGL and Vulkan
and removes that call to the old GLSL IR pass
lower_variable_index_to_cond_assign()

We want to do this pass in nir to be able to move loop unrolling
to nir.

There is a increase of 1-3 instructions in a small number of shaders,
and 2 Kerbal Space program shaders that increase by 32 instructions.

Shader-db results BDW:

total instructions in shared programs: 8705873 -> 8706194 (0.00%)
instructions in affected programs: 32515 -> 32836 (0.99%)
helped: 3
HURT: 79

total cycles in shared programs: 74618120 -> 74583476 (-0.05%)
cycles in affected programs: 528104 -> 493460 (-6.56%)
helped: 47
HURT: 37

LOST:   2
GAINED: 0
---
 src/intel/vulkan/anv_pipeline.c        | 10 ----------
 src/mesa/drivers/dri/i965/brw_link.cpp | 26 ++++++++++++++------------
 src/mesa/drivers/dri/i965/brw_nir.c    | 12 ++++++++++++
 3 files changed, 26 insertions(+), 22 deletions(-)

diff --git a/src/intel/vulkan/anv_pipeline.c b/src/intel/vulkan/anv_pipeline.c
index f96fe22..f292f0b 100644
--- a/src/intel/vulkan/anv_pipeline.c
+++ b/src/intel/vulkan/anv_pipeline.c
@@ -183,16 +183,6 @@ anv_shader_compile_to_nir(struct anv_device *device,
 
    nir_shader_gather_info(nir, entry_point->impl);
 
-   nir_variable_mode indirect_mask = 0;
-   if (compiler->glsl_compiler_options[stage].EmitNoIndirectInput)
-      indirect_mask |= nir_var_shader_in;
-   if (compiler->glsl_compiler_options[stage].EmitNoIndirectOutput)
-      indirect_mask |= nir_var_shader_out;
-   if (compiler->glsl_compiler_options[stage].EmitNoIndirectTemp)
-      indirect_mask |= nir_var_local;
-
-   nir_lower_indirect_derefs(nir, indirect_mask);
-
    return nir;
 }
 
diff --git a/src/mesa/drivers/dri/i965/brw_link.cpp b/src/mesa/drivers/dri/i965/brw_link.cpp
index 2b1fa61..41791d4 100644
--- a/src/mesa/drivers/dri/i965/brw_link.cpp
+++ b/src/mesa/drivers/dri/i965/brw_link.cpp
@@ -139,18 +139,20 @@ process_glsl_ir(gl_shader_stage stage,
 
    do_copy_propagation(shader->ir);
 
-   bool lowered_variable_indexing =
-      lower_variable_index_to_cond_assign((gl_shader_stage)stage,
-                                          shader->ir,
-                                          options->EmitNoIndirectInput,
-                                          options->EmitNoIndirectOutput,
-                                          options->EmitNoIndirectTemp,
-                                          options->EmitNoIndirectUniform);
-
-   if (unlikely(brw->perf_debug && lowered_variable_indexing)) {
-      perf_debug("Unsupported form of variable indexing in %s; falling "
-                 "back to very inefficient code generation\n",
-                 _mesa_shader_stage_to_abbrev(shader->Stage));
+   if (brw->gen < 7) {
+      bool lowered_variable_indexing =
+         lower_variable_index_to_cond_assign((gl_shader_stage)stage,
+                                             shader->ir,
+                                             options->EmitNoIndirectInput,
+                                             options->EmitNoIndirectOutput,
+                                             options->EmitNoIndirectTemp,
+                                             options->EmitNoIndirectUniform);
+
+      if (unlikely(brw->perf_debug && lowered_variable_indexing)) {
+         perf_debug("Unsupported form of variable indexing in %s; falling "
+                    "back to very inefficient code generation\n",
+                    _mesa_shader_stage_to_abbrev(shader->Stage));
+      }
    }
 
    bool progress;
diff --git a/src/mesa/drivers/dri/i965/brw_nir.c b/src/mesa/drivers/dri/i965/brw_nir.c
index e8dafae..af646ed 100644
--- a/src/mesa/drivers/dri/i965/brw_nir.c
+++ b/src/mesa/drivers/dri/i965/brw_nir.c
@@ -453,6 +453,18 @@ brw_preprocess_nir(const struct brw_compiler *compiler, nir_shader *nir)
    /* Lower a bunch of stuff */
    OPT_V(nir_lower_var_copies);
 
+   if (compiler->devinfo->gen > 6) {
+      nir_variable_mode indirect_mask = 0;
+      if (compiler->glsl_compiler_options[nir->stage].EmitNoIndirectInput)
+         indirect_mask |= nir_var_shader_in;
+      if (compiler->glsl_compiler_options[nir->stage].EmitNoIndirectOutput)
+         indirect_mask |= nir_var_shader_out;
+      if (compiler->glsl_compiler_options[nir->stage].EmitNoIndirectTemp)
+         indirect_mask |= nir_var_local;
+
+      nir_lower_indirect_derefs(nir, indirect_mask);
+   }
+
    /* Get rid of split copies */
    nir = nir_optimize(nir, is_scalar);
 
-- 
2.7.4