pan/va: Define the LEA_BUFFER instruction

Will be used for SSBO loads/stores on Valhall.

Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Eric R. Smith <eric.smith@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31164>

src/panfrost/compiler/valhall/ISA.xml

@@ -1378,6 +1378,17 @@
     <imm name="offset" start="8" size="16" signed="true"/>
   </group>
 
+  <ins name="LEA_BUFFER" title="Load buffer effective address" message="attribute" opcode="0x6B" unit="LS">
+    <desc>
+      Load effective address of a simple buffer with an offset added.
+    </desc>
+    <sr write="true"/>
+    <sr_count count="2"/>
+    <slot/>
+    <src>Offset</src>
+    <src>Index</src>
+  </ins>
+
   <ins name="ST_CVT" title="Store with conversion" opcode="0x71" unused="true" unit="LS">
     <desc>
       Store to memory with data conversion. The address to store to is given in

src/panfrost/compiler/valhall/test/assembler-cases.txt

@@ -242,3 +242,4 @@ c4 c0 40 10 71 c0 b6 00    LSHIFT_AND.v4i8 r0, 0x1000000.b3333, 0x0.b00, ^r0
 41 40 0b 40 00 c0 aa 00    HADD.v4s8.rhadd r0, ^r1, ^r0
 01 00 c0 80 01 c2 fa 00    ICMP_OR.v4s8.gt.m1 r2, r1, r0, 0x0
 40 41 42 00 01 c0 ba 00    MUX.v4i8 r0, ^r0, ^r1, ^r2
+c0 c0 00 00 04 82 6b 00    LEA_BUFFER.slot0 @r2:r3, 0x0, 0x0