Reorganize the global value kinds. (#490)

* Reorganize the global value kinds.

This:
 - renames "deref" global values to "load" and gives it a offset that works
   like the "load" instructions' does
 - adds an explicit "iadd_imm" global value kind, which replaces the
   builtin iadd in "vmctx" and "deref" global values.
 - also renames "globalsym" to "symbol"

lib/codegen/meta-python/base/instructions.py

@@ -506,9 +506,9 @@ global_value = Instruction(
 
 # A specialized form of global_value instructions that only handles
 # symbolic names.
-globalsym_addr = Instruction(
-        'globalsym_addr', r"""
-        Compute the address of global GV, which is a symbolic name.
+symbol_value = Instruction(
+        'symbol_value', r"""
+        Compute the value of global GV, which is a symbolic address.
         """,
         ins=GV, outs=addr)
 

lib/codegen/meta-python/isa/x86/encodings.py

@@ -428,18 +428,18 @@ X86_64.enc(base.func_addr.i64, *r.got_fnaddr8.rex(0x8b, w=1),
 #
 
 # Non-PIC
-X86_32.enc(base.globalsym_addr.i32, *r.gvaddr4(0xb8),
+X86_32.enc(base.symbol_value.i32, *r.gvaddr4(0xb8),
            isap=Not(is_pic))
-X86_64.enc(base.globalsym_addr.i64, *r.gvaddr8.rex(0xb8, w=1),
+X86_64.enc(base.symbol_value.i64, *r.gvaddr8.rex(0xb8, w=1),
            isap=Not(is_pic))
 
 # PIC, colocated
-X86_64.enc(base.globalsym_addr.i64, *r.pcrel_gvaddr8.rex(0x8d, w=1),
+X86_64.enc(base.symbol_value.i64, *r.pcrel_gvaddr8.rex(0x8d, w=1),
            isap=is_pic,
            instp=IsColocatedData())
 
 # PIC, non-colocated
-X86_64.enc(base.globalsym_addr.i64, *r.got_gvaddr8.rex(0x8b, w=1),
+X86_64.enc(base.symbol_value.i64, *r.got_gvaddr8.rex(0x8b, w=1),
            isap=is_pic)
 
 #