tgsi: add a TXQS opcode to retrieve the number of texture samples

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Roland Scheidegger <sroland@vmware.com>
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>

src/gallium/auxiliary/tgsi/tgsi_info.c

@@ -141,7 +141,7 @@ static const struct tgsi_opcode_info opcode_info[TGSI_OPCODE_LAST] =
    { 0, 0, 0, 1, 1, 0, NONE, "ENDLOOP", TGSI_OPCODE_ENDLOOP },
    { 0, 0, 0, 0, 1, 0, NONE, "ENDSUB", TGSI_OPCODE_ENDSUB },
    { 1, 1, 1, 0, 0, 0, OTHR, "TXQ_LZ", TGSI_OPCODE_TXQ_LZ },
-   { 0, 0, 0, 0, 0, 0, NONE, "", 104 },     /* removed */
+   { 1, 1, 1, 0, 0, 0, OTHR, "TXQS", TGSI_OPCODE_TXQS },
    { 0, 0, 0, 0, 0, 0, NONE, "", 105 },     /* removed */
    { 0, 0, 0, 0, 0, 0, NONE, "", 106 },     /* removed */
    { 0, 0, 0, 0, 0, 0, NONE, "NOP", TGSI_OPCODE_NOP },
@@ -331,6 +331,7 @@ tgsi_opcode_infer_type( uint opcode )
    case TGSI_OPCODE_SAD: /* XXX some src args may be signed for SAD ? */
    case TGSI_OPCODE_TXQ:
    case TGSI_OPCODE_TXQ_LZ:
+   case TGSI_OPCODE_TXQS:
    case TGSI_OPCODE_F2U:
    case TGSI_OPCODE_UDIV:
    case TGSI_OPCODE_UMAD:

src/gallium/docs/source/tgsi.rst

@@ -960,7 +960,6 @@ XXX doesn't look like most of the opcodes really belong here.
   For components which don't return a resource dimension, their value
   is undefined.
 
-
 .. math::
 
   lod = src0.x
@@ -973,6 +972,17 @@ XXX doesn't look like most of the opcodes really belong here.
 
   dst.w = texture\_levels(unit)
 
+
+.. opcode:: TXQS - Texture Samples Query
+
+  This retrieves the number of samples in the texture, and stores it
+  into the x component. The other components are undefined.
+
+.. math::
+
+  dst.x = texture\_samples(unit)
+
+
 .. opcode:: TG4 - Texture Gather
 
   As per ARB_texture_gather, gathers the four texels to be used in a bi-linear

src/gallium/include/pipe/p_shader_tokens.h

@@ -402,6 +402,7 @@ struct tgsi_property_data {
 #define TGSI_OPCODE_ENDLOOP             101
 #define TGSI_OPCODE_ENDSUB              102
 #define TGSI_OPCODE_TXQ_LZ              103 /* TXQ for mipmap level 0 */
+#define TGSI_OPCODE_TXQS                104
                                 /* gap */
 #define TGSI_OPCODE_NOP                 107