commit 7dfc5215ff08e992ffe88c577ba15d641e610d75
author Joerg Sonnenberger <joerg@bec.de> Thu Mar 20 01:23:55 2014 +0000
committer Joerg Sonnenberger <joerg@bec.de> Thu Mar 20 01:23:55 2014 +0000
tree d06427900994288ecfb7f01742d852d3ae34e0a9
parent 4fb4f2286edeef6320baa9b7ad475495f95c8c56

Fix DW_CFA_GNU_args_size handling. The primary architecture using this
opcode is VAX. A function call pushes the number of arguments given onto
the stack and "ret" will pop it automatically. The FDE of the caller
contains the amount of stack space used for arguments (and possibly
extra padding), so unwinding has to compensate for this when "returning"
from a function. This is exactly the case when step() is done. The
existing handling in unw_set_reg no longer makes sense.


git-svn-id: https://llvm.org/svn/llvm-project/libcxxabi/trunk@204290 91177308-0d34-0410-b5e6-96231b3b80d8

src/Unwind/UnwindCursor.hpp

diff --git a/src/Unwind/UnwindCursor.hpp b/src/Unwind/UnwindCursor.hpp
index 256a72d..235922f 100644
--- a/src/Unwind/UnwindCursor.hpp
+++ b/src/Unwind/UnwindCursor.hpp
@@ -1041,6 +1041,8 @@
     this->setInfoBasedOnIPRegister(true);
     if (_unwindInfoMissing)
       return UNW_STEP_END;
+    if (_info.gp)
+      setReg(UNW_REG_SP, getReg(UNW_REG_SP) + _info.gp);
   }
 
   return result;

src/Unwind/libunwind.cpp

diff --git a/src/Unwind/libunwind.cpp b/src/Unwind/libunwind.cpp
index 2043ac2..59ff4a7 100644
--- a/src/Unwind/libunwind.cpp
+++ b/src/Unwind/libunwind.cpp
@@ -174,9 +174,6 @@
       pint_t orgArgSize = (pint_t)info.gp;
       uint64_t orgFuncStart = info.start_ip;
       co->setInfoBasedOnIPRegister(false);
-      // and adjust REG_SP if there was a DW_CFA_GNU_args_size
-      if ((orgFuncStart == info.start_ip) && (orgArgSize != 0))
-        co->setReg(UNW_REG_SP, co->getReg(UNW_REG_SP) + orgArgSize);
     }
     return UNW_ESUCCESS;
   }