Mesa (master): spirv_to_dxil: Handle clip/cull distance

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Module: Mesa
Branch: master
Commit: f447c69653f7aa36ec60aaefb8df68b485efdfcd
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=f447c69653f7aa36ec60aaefb8df68b485efdfcd

Author: Jesse Natalie <jenatali at microsoft.com>
Date:   Thu Mar 25 18:27:22 2021 -0700

spirv_to_dxil: Handle clip/cull distance

Clip/cull only needs a little bit of lowering before nir_to_dxil can
handle it. Specifically, we just need to split apart arrays that
straddle the 4-component boundary of location, so that the signature
builder can handle it.

To do that cleanly, we need to add some lowering and optimization passes:
* nir_lower_clip_cull_distance_arrays: Merge clip/cull into a single array,
  which is similar to DXIL's requirements here.
* nir_lower_io_to_temporaries: Ensure that we only have one non-indirect write
  to the clip/cull output.
* nir_split_var_copies and nir_lower_var_copies: Ensure that each array entry
  has an independent write with a constant index
* Optimization loop: Make sure that there's no extra derefs in the way between
  deref_var for the output, deref_array for the component, and store_deref.
Then we can actually lower the clip/cull array cleanly.

Still to do is to sort the variables and add driver_location.

Reviewed-by: Bill Kristiansen <billkris at microsoft.com>
Reviewed-by: Michael Tang <tangm at microsoft.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9846>

---

 src/microsoft/spirv_to_dxil/spirv_to_dxil.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/src/microsoft/spirv_to_dxil/spirv_to_dxil.c b/src/microsoft/spirv_to_dxil/spirv_to_dxil.c
index e0b8447adb1..64cf6a92a11 100644
--- a/src/microsoft/spirv_to_dxil/spirv_to_dxil.c
+++ b/src/microsoft/spirv_to_dxil/spirv_to_dxil.c
@@ -23,6 +23,7 @@
 
 #include "spirv_to_dxil.h"
 #include "nir_to_dxil.h"
+#include "dxil_nir.h"
 #include "shader_enums.h"
 #include "spirv/nir_spirv.h"
 #include "util/blob.h"
@@ -73,6 +74,31 @@ spirv_to_dxil(const uint32_t *words, size_t word_count,
          exec_node_remove(&func->node);
    }
    assert(exec_list_length(&nir->functions) == 1);
+
+   NIR_PASS_V(nir, nir_lower_clip_cull_distance_arrays);
+   NIR_PASS_V(nir, nir_lower_io_to_temporaries, entrypoint->impl, true, true);
+   NIR_PASS_V(nir, nir_split_var_copies);
+   NIR_PASS_V(nir, nir_lower_var_copies);
+
+   {
+      bool progress;
+      do
+      {
+         progress = false;
+         NIR_PASS(progress, nir, nir_copy_prop);
+         NIR_PASS(progress, nir, nir_opt_copy_prop_vars);
+         NIR_PASS(progress, nir, nir_opt_deref);
+         NIR_PASS(progress, nir, nir_opt_dce);
+         NIR_PASS(progress, nir, nir_opt_undef);
+         NIR_PASS(progress, nir, nir_opt_constant_folding);
+         NIR_PASS(progress, nir, nir_opt_cse);
+         NIR_PASS(progress, nir, nir_lower_vars_to_ssa);
+         NIR_PASS(progress, nir, nir_opt_algebraic);
+      } while (progress);
+   }
+
+   NIR_PASS_V(nir, dxil_nir_split_clip_cull_distance);
+
    struct nir_to_dxil_options opts = {0};
 
    struct blob dxil_blob;