[wasm] OOB traps: build protected instruction list during codegen

src/compiler/x64/code-generator-x64.cc

Index: src/compiler/x64/code-generator-x64.cc
diff --git a/src/compiler/x64/code-generator-x64.cc b/src/compiler/x64/code-generator-x64.cc
index 745ac5084166e80b649898fbd5f163ac57ce0af4..b61f89f3c282fe9583e84605ef93e17a8cef281b 100644
--- a/src/compiler/x64/code-generator-x64.cc
+++ b/src/compiler/x64/code-generator-x64.cc
@@ -270,18 +270,21 @@ class OutOfLineRecordWrite final : public OutOfLineCode {
 
 class WasmOutOfLineTrap final : public OutOfLineCode {
  public:
-  WasmOutOfLineTrap(CodeGenerator* gen, Address pc, bool frame_elided,
+  WasmOutOfLineTrap(CodeGenerator* gen, int pc, bool frame_elided,
                     Register context, int32_t position)
       : OutOfLineCode(gen),
+        gen_(gen),
         pc_(pc),
         frame_elided_(frame_elided),
         context_(context),
         position_(position) {}
 
+  // TODO(eholk): Refactor this method to take the code generator as a
+  // parameter.
   void Generate() final {
-    // TODO(eholk): record pc_ and the current pc in a table so that
-    // the signal handler can find it.
-    USE(pc_);
+    int current_pc = __ pc_offset();
+
+    gen_->AddProtectedInstruction(pc_, current_pc);
 
     if (frame_elided_) {
       __ EnterFrame(StackFrame::WASM);
@@ -296,7 +299,8 @@ class WasmOutOfLineTrap final : public OutOfLineCode {
   }
 
  private:
-  Address pc_;
+  CodeGenerator* gen_;
+  int pc_;
   bool frame_elided_;
   Register context_;
   int32_t position_;
@@ -1897,7 +1901,7 @@ CodeGenerator::CodeGenResult CodeGenerator::AssembleArchInstruction(
             __ movl(i.OutputRegister(), i.InputOperand(0));
           }
         } else {
-          Address pc = __ pc();
+          int pc = __ pc_offset();
           __ movl(i.OutputRegister(), i.MemoryOperand());
 
           if (arch_opcode == kX64TrapMovl) {