v4: add comment about intermediate rounding step to MAD Signed-off-by: Karol Herbst <karolher...@gmail.com> Reviewed-by: Nicolai Hähnle <nicolai.haeh...@amd.com> Reviewed-by: Roland Scheidegger <srol...@vmware.com> --- src/gallium/docs/source/tgsi.rst | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/src/gallium/docs/source/tgsi.rst b/src/gallium/docs/source/tgsi.rst index fab001293e..e7afdda3bd 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 @@ -237,6 +243,9 @@ This instruction replicates its result. .. opcode:: MAD - Multiply And Add +Perform a * b + c. The implementation is free to decide whether there is an +intermediate rounding step or not. + .. math:: dst.x = src0.x \times src1.x + src2.x -- 2.13.1 _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
