From: Georg Lehmann <dadschoorse@gmail.com>
Date: Wed, 1 Mar 2023 12:24:30 +0000 (+0100)
Subject: nir/lower_mediump: don't use fp16 for constants if the result is denormal
X-Git-Tag: upstream/23.3.3~12328
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=0a3387a190e9eef969ffc8a4f16ecde122e15c7e;p=platform%2Fupstream%2Fmesa.git

nir/lower_mediump: don't use fp16 for constants if the result is denormal

Image stores are not required to preserve denorms.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Emma Anholt <emma@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21622>
---

diff --git a/src/compiler/nir/nir_lower_mediump.c b/src/compiler/nir/nir_lower_mediump.c
index c1baabf..2e7a40d 100644
--- a/src/compiler/nir/nir_lower_mediump.c
+++ b/src/compiler/nir/nir_lower_mediump.c
@@ -749,7 +749,9 @@ static bool
 const_is_f16(nir_ssa_scalar scalar)
 {
    double value = nir_ssa_scalar_as_float(scalar);
-   return value == _mesa_half_to_float(_mesa_float_to_half(value));
+   uint16_t fp16_val = _mesa_float_to_half(value);
+   bool is_denorm = (fp16_val & 0x7fff) != 0 && (fp16_val & 0x7fff) <= 0x3ff;
+   return value == _mesa_half_to_float(fp16_val) && !is_denorm;
 }
 
 static bool