[Mesa-dev] [PATCH v2 3/7] gallium: add FBFETCH opcode to retrieve the current sample value

[Ilia Mirkin]

Signed-off-by: Ilia Mirkin <imirkin at alum.mit.edu>
---

v1 -> v2: reword FBFETCH opcode to make it more explicit how it is allowed to operate

 src/gallium/auxiliary/tgsi/tgsi_info.c     |  2 +-
 src/gallium/docs/source/tgsi.rst           | 13 +++++++++++++
 src/gallium/include/pipe/p_shader_tokens.h |  2 +-
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/src/gallium/auxiliary/tgsi/tgsi_info.c b/src/gallium/auxiliary/tgsi/tgsi_info.c
index a339ec2..869ef17 100644
--- a/src/gallium/auxiliary/tgsi/tgsi_info.c
+++ b/src/gallium/auxiliary/tgsi/tgsi_info.c
@@ -106,7 +106,7 @@ static const struct tgsi_opcode_info opcode_info[TGSI_OPCODE_LAST] =
    { 1, 3, 0, 0, 0, 0, 0, COMP, "CMP", TGSI_OPCODE_CMP },
    { 1, 1, 0, 0, 0, 0, 0, CHAN, "SCS", TGSI_OPCODE_SCS },
    { 1, 2, 1, 0, 0, 0, 0, OTHR, "TXB", TGSI_OPCODE_TXB },
-   { 0, 1, 0, 0, 0, 0, 1, NONE, "", 69 },      /* removed */
+   { 1, 1, 0, 0, 0, 0, 0, OTHR, "FBFETCH", TGSI_OPCODE_FBFETCH },
    { 1, 2, 0, 0, 0, 0, 0, COMP, "DIV", TGSI_OPCODE_DIV },
    { 1, 2, 0, 0, 0, 0, 0, REPL, "DP2", TGSI_OPCODE_DP2 },
    { 1, 2, 1, 0, 0, 0, 0, OTHR, "TXL", TGSI_OPCODE_TXL },
diff --git a/src/gallium/docs/source/tgsi.rst b/src/gallium/docs/source/tgsi.rst
index d2d30b4..4d7ec90 100644
--- a/src/gallium/docs/source/tgsi.rst
+++ b/src/gallium/docs/source/tgsi.rst
@@ -2561,6 +2561,19 @@ Resource Access Opcodes
   image, while .w will contain the number of samples for multi-sampled
   images.
 
+.. opcode:: FBFETCH - Load data from framebuffer
+
+  Syntax: ``FBFETCH dst, output``
+
+  Example: ``FBFETCH TEMP[0], OUT[0]``
+
+  This is only valid on ``COLOR`` semantic outputs. Returns the color
+  of the current position in the framebuffer from before this fragment
+  shader invocation. May return the same value from multiple calls for
+  a particular output within a single invocation. Note that result may
+  be undefined if a fragment is drawn multiple times without a blend
+  barrier in between.
+
 
 .. _threadsyncopcodes:
 
diff --git a/src/gallium/include/pipe/p_shader_tokens.h b/src/gallium/include/pipe/p_shader_tokens.h
index 3384035..f9b658d 100644
--- a/src/gallium/include/pipe/p_shader_tokens.h
+++ b/src/gallium/include/pipe/p_shader_tokens.h
@@ -397,7 +397,7 @@ struct tgsi_property_data {
 #define TGSI_OPCODE_CMP                 66
 #define TGSI_OPCODE_SCS                 67
 #define TGSI_OPCODE_TXB                 68
-                                /* gap */
+#define TGSI_OPCODE_FBFETCH             69
 #define TGSI_OPCODE_DIV                 70
 #define TGSI_OPCODE_DP2                 71
 #define TGSI_OPCODE_TXL                 72
-- 
2.10.2