renovates the LLVM backend

Droping support of old LLVM and legacy backends
-----------------------------------------------

We drop a lot of old code (minus 3k lines of code) thus removing the support
burden and making it easier to maintain, fix, and upgrade the code.

Fixes #1166

Simplifies the implementation
-----------------------------

The remaining code base is significanly simplified. We dropped the
separation between relocatable and non-relocatable files, removed any
transformations of addresses from the LLVM backend (we now emit
absolute virtual addresses). The whole logic of transforming from the
llvm view to the bap image view now fits into a hundred lines of
code (instead of hundreds lines spread across 16 files as it was
before).

Fixes #1183
Fixes #1189

Produces more information
-------------------------------

The relocation information is now emitted for all files (not only for
relocatable). Also, removes tons of checks that were preventing our
backends from emitting valuable symbolic information.

Paves the road to #1135 and #1161

lib/bap/bap.mli

@@ -5538,6 +5538,7 @@ module Std : sig
       type addr = int64
       type size = int64
       type off  = int64
+      type value = int64
 
       (** a contiguous piece of memory.  *)
       type 'a region = {
@@ -5566,41 +5567,56 @@ module Std : sig
       (** [subarch name] the subarchitecture, when applicable,
           e.g., v7, v8, r2, etc. Should be appended to the arch
           name to get the full description, e.g., armv7.
+
+          @since 2.2.0
       *)
       val subarch : (string, (string -> 'a) -> 'a) Ogre.attribute
 
 
       (** [vendor name] the second part of the build triplet,
-          e.g., apple, pc, ibm, unknown. Could be just an empty string.
+          e.g., apple, pc, ibm, unknown. Could be just an empty
+          string.
+
+          @since 2.2.0
       *)
       val vendor : (string, (string -> 'a) -> 'a) Ogre.attribute
 
 
       (** [system name] the operating system name, for which the
           binary is specifically built, e.g., ananas, ios, linux.
+
+          @since 2.2.0
       *)
       val system : (string, (string -> 'a) -> 'a) Ogre.attribute
 
 
       (** [abi name] the environment/toolchain/abi under which the
           binary is expected to be run, e.g., gnu, android, msvc
+
+          @since 2.2.0
       *)
       val abi : (string, (string -> 'a) -> 'a) Ogre.attribute
 
 
       (** [bits m] is the bitness of the target architecture, e.g.,
           16, 32, 64.
+
+          @since 2.2.0
       *)
       val bits : (size, (size -> 'a) -> 'a) Ogre.attribute
 
 
       (** [is_little_endian yes-or-no] is [true] if the target is
-          little endian.   *)
+          little endian.
+
+          @since 2.2.0  *)
       val is_little_endian : (bool, (bool -> 'a) -> 'a) Ogre.attribute
 
 
       (** [bias offset] the value by which all addresses are biased
-          wrt to the real addresses in the binary. *)
+          wrt to the real addresses in the binary.
+
+          @since 2.2.0 *)
       val bias : (off, (off -> 'a) -> 'a) Ogre.attribute
 
       (** [segment addr size readable writable executable] a memory
@@ -5614,7 +5630,7 @@ module Std : sig
       (** [code_start addr] an address starts a code sequence *)
       val code_start : (addr, (addr -> 'a) -> 'a) Ogre.attribute
 
-      (** [entry_point addr] an address is a program entry point  *)
+      (** [entry_point addr] an address is the program entry point  *)
       val entry_point : (addr, (addr -> 'a) -> 'a) Ogre.attribute
 
       (** [symbol_chunk addr size root] a contiguous piece of a program
@@ -5652,8 +5668,17 @@ module Std : sig
           i.e., an address of a first byte of the image.  *)
       val base_address : (addr, (addr -> 'a) -> 'a) Ogre.attribute
 
+
+      (** [code_region addr size off] the memory region in the file
+          with the given offset [off] and [size] is code that should be loaded
+          at the specified virtual address [addr]. *)
       val code_region :
         (addr * size * off, (addr -> size -> off -> 'a) -> 'a) Ogre.attribute
+
+      (** [symbol_value addr value] the symbol at address the
+          specified [value].  *)
+      val symbol_value :
+        (addr * value, (addr -> value -> 'a) -> 'a) Ogre.attribute
     end
   end
 

lib/bap_image/bap_image.ml

@@ -332,13 +332,15 @@ module Scheme = struct
   type addr = int64
   type size = int64
   type off = int64
+  type value = int64
   type 'a region = {addr : int64; size: int64; info : 'a}
   let region addr size info = {addr; size; info}
   let void_region addr size = {addr; size; info = ()}
 
   let off  = "off"  %: int
   let size = "size" %: int
   let addr = "addr" %: int
+  let value = "value" %: int
   let name = "name" %: str
   let root = "root" %: int
   let readable   = "r" %: bool
@@ -378,6 +380,9 @@ module Scheme = struct
   let external_reference () =
     declare "external-reference" (scheme addr $ name) Tuple.T2.create
   let base_address () = declare "base-address" (scheme addr) ident
+
+  let symbol_value () =
+    declare "symbol-value" (scheme addr $ value) Tuple.T2.create
 end
 
 

lib/bap_image/bap_image.mli

@@ -81,6 +81,7 @@ module Scheme : sig
   type addr = int64
   type size = int64
   type off = int64
+  type value = int64
 
   type 'a region = {addr : addr; size : int64; info : 'a}
 
@@ -130,4 +131,6 @@ module Scheme : sig
   val code_region :
     (addr * size * off, (addr -> size -> off -> 'a) -> 'a) Ogre.attribute
 
+  val symbol_value :
+    (addr * value, (addr -> value -> 'a) -> 'a) Ogre.attribute
 end

lib/bap_llvm/bap_llvm.ml

@@ -10,5 +10,6 @@ module Std = struct
 
   let llvm_version = strip_version Bap_llvm_config.version
   let init_disassembler = Bap_llvm_disasm.init
-  let init_loader = Bap_llvm_ogre_loader.init
+  let init_loader ?base ?pdb_path () =
+    ok_exn @@ Bap_llvm_loader.init ?base ?pdb_path ()
 end