nir: Add Panfrost-specific blending intrinsic

This gives more flexibility than the normal store_deref/store_output
versions (particularly, it allows us to abuse the type system in awful
ways, which is necessary for efficient format conversion in blend
shaders.)

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Acked-by: Karol Herbst <kherbst@redhat.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/src/compiler/nir/nir_intrinsics.py b/src/compiler/nir/nir_intrinsics.py
index e4f94257acd..0fd8a30eb4d 100644
--- a/src/compiler/nir/nir_intrinsics.py
+++ b/src/compiler/nir/nir_intrinsics.py
@@ -760,3 +760,19 @@ intrinsic("ssbo_atomic_or_ir3",         src_comp=[1, 1, 1, 1],    dest_comp=1)
 intrinsic("ssbo_atomic_xor_ir3",        src_comp=[1, 1, 1, 1],    dest_comp=1)
 intrinsic("ssbo_atomic_exchange_ir3",   src_comp=[1, 1, 1, 1],    dest_comp=1)
 intrinsic("ssbo_atomic_comp_swap_ir3",  src_comp=[1, 1, 1, 1, 1], dest_comp=1)
+
+# Intrinsics used by the Midgard/Bifrost blend pipeline. These are defined
+# within a blend shader to read/write the raw value from the tile buffer,
+# without applying any format conversion in the process. If the shader needs
+# usable pixel values, it must apply format conversions itself.
+#
+# These definitions are generic, but they are explicitly vendored to prevent
+# other drivers from using them, as their semantics is defined in terms of the
+# Midgard/Bifrost hardware tile buffer and may not line up with anything sane.
+# One notable divergence is sRGB, which is asymmetric: raw_input_pan requires
+# an sRGB->linear conversion, but linear values should be written to
+# raw_output_pan and the hardware handles linear->sRGB.
+
+# src[] = { value }
+store("raw_output_pan", 1, [])
+load("raw_output_pan", 0, [], [CAN_ELIMINATE, CAN_REORDER])