Refactoring of conversion ops, part 1: add IR_CONV.

lib/dump.lua

@@ -236,6 +236,15 @@ local litname = {
     return s
   end}),
   ["XLOAD "] = { [0] = "", "R", "U", "RU", },
+  ["CONV  "] = setmetatable({}, { __index = function(t, mode)
+    local s = irtype[band(mode, 31)]
+    if band(mode, 0x100) ~= 0 then s = s.." trunc"
+    elseif band(mode, 0x200) ~= 0 then s = s.." sext" end
+    local c = shr(mode, 10)
+    if c == 2 then s = s.." index" elseif c == 3 then s = s.." check" end
+    t[mode] = s
+    return s
+  end}),
   ["TOINT "] = tointname,
   ["TOI64 "] = tointname,
   ["FLOAD "] = vmdef.irfield,