intel/executor: Add example using scalar register and send gather

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32236>

src/intel/executor/examples/gfx30.scalar_reg.lua

@@ -0,0 +1,71 @@
+-- Xe3 adds a new ARF to store scalar values.  It supports only a limited
+-- set of operations.
+
+check_ver(30)
+
+local r = execute {
+  src=[[
+    // The new scalar register s0 has 32 bytes.
+    //
+    // Only MOV can have scalar as destination.  Offsets in scalar
+    // must be aligned to word boundary.  This non-overlapping MOVs
+    // will fill the first 16 bytes.
+
+    mov(1)   s0<1>UW     0x1111UW;
+
+    mov(1)   r2<1>UW     0x2222UW;
+    mov(1)   s0.1<1>UW   r2<0,1,0>UW  {I@1};
+
+    mov(1)   s0.1<1>UD   0x33333333UD {I@1};
+
+    mov(4)   r4<1>UW     0x4444UW;
+    mov(1)   s0.1<1>UQ   r4<0,1,0>UQ {I@1};
+
+
+    // Scalar content can be broadcasted back into GRFs.
+
+    mov(16)  r20<1>UD    s0.0<0,1,0>UD;
+    mov(16)  r32<1>UD    s0.1<0,1,0>UD;
+    mov(16)  r96<1>UD    s0.2<0,1,0>UD;
+    mov(16)  r64<1>UD    s0.3<0,1,0>UD;
+
+
+    // Scalar can store a list of register numbers to be used as source for
+    // SEND.  Note the scalar will contain the hex value for r11 and r20.
+    // And the scalar register is indexed as bytes in r[...] syntax, unlike
+    // in the MOV.
+
+    mov(16)  r11<1>UD    0x30000000UD;
+    mov(1)   s0.4<1>UD   0x0000140bUD;
+
+    send(16) nullUD      r[s0.16]       0x04000504      0x00000000   ugm MsgDesc: () { I@1 $1 };
+
+
+    // A larger SEND, note that registers for the payload don't need to be
+    // contiguous, the hardware will gather them together.
+
+    add(16)  r11<1>UD    r11<1,1,0>UD  0x4UD     {A@1, $1.src};
+    mov(1)   s0.4<1>UD   0x4060200bUD;
+
+    send(16) nullUD      r[s0.16]       0x08002504      0x00000000   ugm MsgDesc: ( ) { I@1 $1 };
+
+    @eot
+  ]]
+}
+
+expected = {[0] = 0x22221111, 0x33333333, 0x44444444, 0x44444444}
+
+print("result")
+dump(r, 4)
+
+print("expected")
+dump(expected, 4)
+
+for i=0,3 do
+  if r[i] ~= expected[i] then
+    print("FAIL")
+    return
+  end
+end
+
+print("OK")