[Mesa-dev] [PATCH v3 06/10] gallium/docs: add precise instruction modifier

[Karol Herbst]

Signed-off-by: Karol Herbst <karolherbst at gmail.com>
---
 src/gallium/docs/source/tgsi.rst | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/gallium/docs/source/tgsi.rst b/src/gallium/docs/source/tgsi.rst
index c65d721dec..76c82b3e88 100644
--- a/src/gallium/docs/source/tgsi.rst
+++ b/src/gallium/docs/source/tgsi.rst
@@ -26,7 +26,13 @@ each of the components of *dst*. When this happens, the result is said to be
 Modifiers
 ^^^^^^^^^^^^^^^
 
-TGSI supports modifiers on inputs (as well as saturate modifier on instructions).
+TGSI supports modifiers on inputs (as well as saturate and precise modifier
+on instructions).
+
+For arithmetic instruction having a precise modifier certain optimizations
+which may alter the result are disallowed. Example: *add(mul(a,b),c)* can't be
+optimized to TGSI_OPCODE_MAD, because some hardware only supports the fused
+MAD instruction.
 
 For inputs which have a floating point type, both absolute value and
 negation modifiers are supported (with absolute value being applied
-- 
2.13.1