pan/va: Add LD_CVT

Adds LD_CVT instruction for loading memory with conversion.

Reviewed-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/37007>

src/panfrost/compiler/valhall/ISA.xml

@@ -1433,6 +1433,23 @@
     <src>Index</src>
   </ins>
 
+  <ins name="LD_CVT" title="Load with conversion" opcode="0x70" unused="true" unit="LS">
+    <desc>
+      Load from memory with data conversion. The address to load from is given in
+      the first source, which must be a 64-bit register (a pair of 32-bit
+      registers). The other source is the conversion descriptor used for the load.
+    </desc>
+    <slot/>
+    <va_mod name="memory_access" start="37" size="3"/>
+    <vecsize/>
+    <regfmt/>
+    <sr write="true"/>
+    <sr_count/>
+    <src size="64">64-bit address to load from</src>
+    <imm name="offset" start="8" size="8"/>
+    <src>Internal conversion descriptor</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/va_pack.c

@@ -975,6 +975,15 @@ va_pack_instr(const bi_instr *I, unsigned arch)
 
       break;
 
+   case BI_OPCODE_LD_CVT:
+      hex |= (uint64_t)va_pack_src(I, 0);
+      hex |= va_pack_byte_offset(I);
+
+      /* Conversion descriptor */
+      hex |= (uint64_t)va_pack_src(I, 2) << 16;
+      hex |= va_pack_memory_access(I) << 37;
+      break;
+
    case BI_OPCODE_ST_CVT:
       /* Staging read */
       hex |= va_pack_store(I);