Mark setjmp as "returns twice" and turn off SimpleCoalescing when called.

src/IceIntrinsics.h

Index: src/IceIntrinsics.h
diff --git a/src/IceIntrinsics.h b/src/IceIntrinsics.h
index b9c793a5d8adbe810fcfe8db6ebb2d8019a2a56d..ec28f6077fe0c82f78df3d44459d139b3cb01bc3 100644
--- a/src/IceIntrinsics.h
+++ b/src/IceIntrinsics.h
@@ -89,14 +89,13 @@ public:
   static bool VerifyMemoryOrder(uint64_t Order);
 
   // Basic attributes related to each intrinsic, that are relevant to
-  // code generation. We will want to have more attributes (e.g., Setjmp
-  // returns twice and which affects stack coloring) once the lowering
-  // cares about such attributes. Perhaps the attributes representation
-  // can be shared with general function calls, though most functions
-  // will be opaque.
+  // code generation. Perhaps the attributes representation can be shared
+  // with general function calls, but PNaCl currently strips all
+  // attributes from functions.
   struct IntrinsicInfo {
-    IntrinsicID ID : 31;
+    IntrinsicID ID : 30;
     bool HasSideEffects : 1;
+    bool ReturnsTwice : 1;
   };
 
   // The complete set of information about an intrinsic.