[Mesa-dev] [PATCH 16/42] panfrost/midgard: Implement f2f16/f2f32

[Alyssa Rosenzweig]

These conversions handle half-floats within the shader.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig at collabora.com>
---
 .../drivers/panfrost/midgard/midgard_compile.c | 18 ++++++++++++++++++
 .../panfrost/midgard/midgard_nir_algebraic.py  |  5 ++++-
 .../panfrost/midgard/nir_lower_framebuffer.c   |  7 +++++--
 3 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/src/gallium/drivers/panfrost/midgard/midgard_compile.c b/src/gallium/drivers/panfrost/midgard/midgard_compile.c
index 353875d173f..fc17ad2b051 100644
--- a/src/gallium/drivers/panfrost/midgard/midgard_compile.c
+++ b/src/gallium/drivers/panfrost/midgard/midgard_compile.c
@@ -907,6 +907,24 @@ emit_alu(compiler_context *ctx, nir_alu_instr *instr)
                 break;
         }
 
+        case nir_op_f2f16: {
+                assert(src_bitsize == 32);
+
+                op = midgard_alu_op_fmov;
+                dest_override = midgard_dest_override_lower;
+                break;
+        }
+
+        case nir_op_f2f32: {
+                assert(src_bitsize == 16);
+
+                op = midgard_alu_op_fmov;
+                half_2 = true;
+                reg_mode++;
+                break;
+        }
+                
+
         /* For greater-or-equal, we lower to less-or-equal and flip the
          * arguments */
 
diff --git a/src/gallium/drivers/panfrost/midgard/midgard_nir_algebraic.py b/src/gallium/drivers/panfrost/midgard/midgard_nir_algebraic.py
index b05c193e507..871195b48ca 100644
--- a/src/gallium/drivers/panfrost/midgard/midgard_nir_algebraic.py
+++ b/src/gallium/drivers/panfrost/midgard/midgard_nir_algebraic.py
@@ -53,7 +53,10 @@ converts = [
     (('u2u8', 'a at 32'), ('u2u8', ('u2u16', a))),
 
     (('i2i32', 'a at 8'), ('i2i32', ('i2i16', a))),
-    (('u2u32', 'a at 8'), ('u2u32', ('u2u16', a)))
+    (('u2u32', 'a at 8'), ('u2u32', ('u2u16', a))),
+
+    (('f2i32', 'a at 16'), ('f2i32', ('f2f32', a))),
+    (('f2u32', 'a at 16'), ('f2u32', ('f2f32', a))),
 ]
 
 # Midgard scales fsin/fcos arguments by pi.
diff --git a/src/gallium/drivers/panfrost/midgard/nir_lower_framebuffer.c b/src/gallium/drivers/panfrost/midgard/nir_lower_framebuffer.c
index 5f3115b6ae8..5233fbc9280 100644
--- a/src/gallium/drivers/panfrost/midgard/nir_lower_framebuffer.c
+++ b/src/gallium/drivers/panfrost/midgard/nir_lower_framebuffer.c
@@ -44,8 +44,11 @@
 static nir_ssa_def *
 nir_float_to_native(nir_builder *b, nir_ssa_def *c_float)
 {
-   /* First, we scale from [0, 1] to [0, 255.0] */
-   nir_ssa_def *scaled = nir_fmul_imm(b, nir_fsat(b, c_float), 255.0);
+   /* First, we degrade quality to fp16; we don't need the extra bits */
+   nir_ssa_def *degraded = nir_f2f16(b, c_float);
+
+   /* Scale from [0, 1] to [0, 255.0] */
+   nir_ssa_def *scaled = nir_fmul_imm(b, nir_fsat(b, degraded), 255.0);
 
    /* Next, we type convert */
    nir_ssa_def *converted = nir_u2u8(b, nir_f2u32(b,
-- 
2.20.1