From 5f3ab7979f5a69b958dfe3971089a47b902a4eee Mon Sep 17 00:00:00 2001
From: Ben Vanik <ben.vanik@gmail.com>
Date: Sun, 1 Feb 2015 11:38:16 -0800
Subject: [PATCH] --break_on_debugbreak

---
 src/alloy/alloy-private.h            | 1 +
 src/alloy/alloy.cc                   | 1 +
 src/alloy/backend/x64/x64_emitter.cc | 5 ++++-
 3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/alloy/alloy-private.h b/src/alloy/alloy-private.h
index 3efde3d21..e20e04806 100644
--- a/src/alloy/alloy-private.h
+++ b/src/alloy/alloy-private.h
@@ -19,5 +19,6 @@ DECLARE_bool(validate_hir);
 
 DECLARE_uint64(break_on_instruction);
 DECLARE_uint64(break_on_memory);
+DECLARE_bool(break_on_debugbreak);
 
 #endif  // ALLOY_ALLOY_PRIVATE_H_
diff --git a/src/alloy/alloy.cc b/src/alloy/alloy.cc
index 2f6d095f3..3435a4950 100644
--- a/src/alloy/alloy.cc
+++ b/src/alloy/alloy.cc
@@ -32,3 +32,4 @@ DEFINE_uint64(break_on_instruction, 0,
               "int3 before the given guest address is executed.");
 DEFINE_uint64(break_on_memory, 0,
               "int3 on read/write to the given memory address.");
+DEFINE_bool(break_on_debugbreak, true, "int3 on JITed __debugbreak requests.");
diff --git a/src/alloy/backend/x64/x64_emitter.cc b/src/alloy/backend/x64/x64_emitter.cc
index a404f52fc..77a661eda 100644
--- a/src/alloy/backend/x64/x64_emitter.cc
+++ b/src/alloy/backend/x64/x64_emitter.cc
@@ -9,6 +9,7 @@
 
 #include "alloy/backend/x64/x64_emitter.h"
 
+#include "alloy/alloy-private.h"
 #include "alloy/backend/x64/x64_backend.h"
 #include "alloy/backend/x64/x64_code_cache.h"
 #include "alloy/backend/x64/x64_function.h"
@@ -371,7 +372,9 @@ void X64Emitter::Trap(uint16_t trap_type) {
     case 22:
       // Always trap?
       // TODO(benvanik): post software interrupt to debugger.
-      db(0xCC);
+      if (FLAGS_break_on_debugbreak) {
+        db(0xCC);
+      }
       break;
     default:
       PLOGW("Unknown trap type %d", trap_type);