[PATCH][cxxabi] Properly sign-extend encoded sdata.

[Patrick Wildt]

Hi,

In the case of sdata, the returned number has to be properly sign
extended, otherwise subtractions don't work.

In sdata8, the result might have to be casted to sint_t instead of
pint_t to be visually correct.  It probably doesn't do any harm
as it is now.

\Patrick

>From d802fee6f399cf1f5f767b1fd78f07a555b77eef Mon Sep 17 00:00:00 2001
From: Patrick Wildt <patrick at blueri.se>
Date: Fri, 11 Apr 2014 14:17:40 +0200
Subject: [PATCH] Properly sign extend sdata.

---
 src/Unwind/AddressSpace.hpp | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/Unwind/AddressSpace.hpp b/src/Unwind/AddressSpace.hpp
index aac8b7f..ce95459 100644
--- a/src/Unwind/AddressSpace.hpp
+++ b/src/Unwind/AddressSpace.hpp
@@ -196,12 +196,14 @@ inline LocalAddressSpace::pint_t LocalAddressSpace::getEncodedP(pint_t &addr,
     result = (pint_t)getSLEB128(addr, end);
     break;
   case DW_EH_PE_sdata2:
-    result = (uint16_t)get16(addr);
+    /* signed so that it extends negative numbers */
+    result = (int16_t)get16(addr);
     p += 2;
     addr = (pint_t) p;
     break;
   case DW_EH_PE_sdata4:
-    result = (uint32_t)get32(addr);
+    /* signed so that it extends negative numbers */
+    result = (int32_t)get32(addr);
     p += 4;
     addr = (pint_t) p;
     break;
-- 
1.8.5.2 (Apple Git-48)