Add primitives-based constructor for RelocIterator

This is meant to be used from the native wasm datastructures

Bug: v8:6876
Change-Id: Ie865cf3277b24f25e1845bf32837be1a24047472
Reviewed-on: https://chromium-review.googlesource.com/764502
Commit-Queue: Mircea Trofin <mtrofin@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49310}

src/assembler.cc

@@ -552,6 +552,7 @@ RelocIterator::RelocIterator(Code* code, int mode_mask) {
   rinfo_.host_ = code;
   rinfo_.pc_ = code->instruction_start();
   rinfo_.data_ = 0;
+  rinfo_.constant_pool_ = code->constant_pool();
   // Relocation info is read backwards.
   pos_ = code->relocation_start() + code->relocation_size();
   end_ = code->relocation_start();
@@ -573,6 +574,21 @@ RelocIterator::RelocIterator(const CodeDesc& desc, int mode_mask) {
   next();
 }
 
+RelocIterator::RelocIterator(Vector<byte> instructions,
+                             Vector<const byte> reloc_info, Address const_pool,
+                             int mode_mask) {
+  rinfo_.pc_ = instructions.start();
+  rinfo_.data_ = 0;
+  rinfo_.constant_pool_ = const_pool;
+  // Relocation info is read backwards.
+  pos_ = reloc_info.start() + reloc_info.size();
+  end_ = reloc_info.start();
+  done_ = false;
+  mode_mask_ = mode_mask;
+  if (mode_mask_ == 0) pos_ = end_;
+  next();
+}
+
 // -----------------------------------------------------------------------------
 // Implementation of RelocInfo
 

src/assembler.h

@@ -479,7 +479,6 @@ class RelocInfo {
   Mode rmode() const {  return rmode_; }
   intptr_t data() const { return data_; }
   Code* host() const { return host_; }
-  void set_host(Code* host) { host_ = host; }
 
   // Apply a relocation by delta bytes. When the code object is moved, PC
   // relative addresses have to be updated as well as absolute addresses
@@ -612,6 +611,7 @@ class RelocInfo {
   Mode rmode_;
   intptr_t data_;
   Code* host_;
+  Address constant_pool_ = nullptr;
   friend class RelocIterator;
 };
 
@@ -677,6 +677,11 @@ class RelocIterator: public Malloced {
   // iteration iff bit k of mode_mask is set.
   explicit RelocIterator(Code* code, int mode_mask = -1);
   explicit RelocIterator(const CodeDesc& desc, int mode_mask = -1);
+  explicit RelocIterator(Vector<byte> instructions,
+                         Vector<const byte> reloc_info, Address const_pool,
+                         int mode_mask = -1);
+  RelocIterator(RelocIterator&&) = default;
+  RelocIterator& operator=(RelocIterator&&) = default;
 
   // Iteration
   bool done() const { return done_; }
@@ -711,8 +716,8 @@ class RelocIterator: public Malloced {
     return (mode_mask_ & (1 << mode)) ? (rinfo_.rmode_ = mode, true) : false;
   }
 
-  byte* pos_;
-  byte* end_;
+  const byte* pos_;
+  const byte* end_;
   RelocInfo rinfo_;
   bool done_;
   int mode_mask_;