gallium: add FMA and DFMA opcodes (v3)

Needed by ARB_gpu_shader5.

v2: select DMAD for FMA with double precision
v3: add and select DFMA

Reviewed-by: Ilia Mirkin <[email protected]>

2 files changed, 28 insertions, 0 deletions

diff --git a/src/gallium/docs/source/screen.rst b/src/gallium/docs/source/screen.rst
index e0fd1a2dbac..26cc9ffc6f7 100644
--- a/src/gallium/docs/source/screen.rst
+++ b/src/gallium/docs/source/screen.rst
@@ -336,6 +336,8 @@ to be 0.
   is supported. If it is, DTRUNC/DCEIL/DFLR/DROUND opcodes may be used.
 * ``PIPE_SHADER_CAP_TGSI_DFRACEXP_DLDEXP_SUPPORTED``: Whether DFRACEXP and
   DLDEXP are supported.
+* ``PIPE_SHADER_CAP_TGSI_FMA_SUPPORTED``: Whether FMA and DFMA (doubles only)
+  are supported.
 
 
 .. _pipe_compute_cap:
diff --git a/src/gallium/docs/source/tgsi.rst b/src/gallium/docs/source/tgsi.rst
index b0a975aa70a..7771136f167 100644
--- a/src/gallium/docs/source/tgsi.rst
+++ b/src/gallium/docs/source/tgsi.rst
@@ -272,6 +272,21 @@ This instruction replicates its result.
   dst.w = src0.w \times src1.w + (1 - src0.w) \times src2.w
 
 
+.. opcode:: FMA - Fused Multiply-Add
+
+Perform a * b + c with no intermediate rounding step.
+
+.. math::
+
+  dst.x = src0.x \times src1.x + src2.x
+
+  dst.y = src0.y \times src1.y + src2.y
+
+  dst.z = src0.z \times src1.z + src2.z
+
+  dst.w = src0.w \times src1.w + src2.w
+
+
 .. opcode:: DP2A - 2-component Dot Product And Add
 
 .. math::
@@ -1962,6 +1977,17 @@ source is an integer.
   dst.zw = src0.zw \times src1.zw + src2.zw
 
 
+.. opcode:: DFMA - Fused Multiply-Add
+
+Perform a * b + c with no intermediate rounding step.
+
+.. math::
+
+  dst.xy = src0.xy \times src1.xy + src2.xy
+
+  dst.zw = src0.zw \times src1.zw + src2.zw
+
+
 .. opcode:: DRCP - Reciprocal
 
 .. math::