Ignore "push/pop {sp}" in emulation based unwinding

[tberghammer]

Summary

Ignore "push/pop {sp}" in emulation based unwinding

These instructions confusing the unwind code because in case of a
push it assumes that the original value of a register is pushed to
the stack what is not necessarily true in case of SP. The same is
true for the pop (in the opposite way).

[jasonmolenda]

Looks good to me.

source/Plugins/UnwindAssembly/InstEmulation/UnwindAssemblyInstEmulation.cpp

switch (context.type)
         case EmulateInstruction::eContextReturnFromException:
         case EmulateInstruction::eContextPopRegisterOffStack:
         case EmulateInstruction::eContextAdjustStackPointer:
             break;
             
         case EmulateInstruction::eContextPushRegisterOnStack:
             {
                 uint32_t reg_num = LLDB_INVALID_REGNUM;
-                const uint32_t unwind_reg_kind = m_unwind_plan_ptr->GetRegisterKind();
+                uint32_t generic_regnum = LLDB_INVALID_REGNUM;
                 if (context.info_type == EmulateInstruction::eInfoTypeRegisterToRegisterPlusOffset)
+                {
+                    const uint32_t unwind_reg_kind = m_unwind_plan_ptr->GetRegisterKind();
                     reg_num = context.info.RegisterToRegisterPlusOffset.data_reg.kinds[unwind_reg_kind];
+                    generic_regnum = context.info.RegisterToRegisterPlusOffset.data_reg.kinds[eRegisterKindGeneric];
+                }
                 else
                     assert (!"unhandled case, add code to handle this!");
 
-                if (reg_num != LLDB_INVALID_REGNUM)
+                if (reg_num != LLDB_INVALID_REGNUM && generic_regnum != LLDB_REGNUM_GENERIC_SP)
                 {
                     if (m_pushed_regs.find (reg_num) == m_pushed_regs.end())
                     {
                         m_pushed_regs[reg_num] = addr;
                         const int32_t offset = addr - m_initial_sp;
                         m_curr_row->SetRegisterLocationToAtCFAPlusOffset (reg_num, offset, cant_replace);
                         m_curr_row_modified = true;
                     }
//            }
                     m_forward_branch_offset = context.info.signed_immediate;
                 }
             }
             break;
 
         case EmulateInstruction::eContextPopRegisterOffStack:
             {
                 const uint32_t reg_num = reg_info->kinds[m_unwind_plan_ptr->GetRegisterKind()];
-                if (reg_num != LLDB_INVALID_REGNUM)
+                const uint32_t generic_regnum = reg_info->kinds[eRegisterKindGeneric];
+                if (reg_num != LLDB_INVALID_REGNUM && generic_regnum != LLDB_REGNUM_GENERIC_SP)
                 {
                     m_curr_row->SetRegisterLocationToSame (reg_num, /*must_replace*/ false);
                     m_curr_row_modified = true;
                 }
             }
             break;
 
         case EmulateInstruction::eContextSetFramePointer:

test/functionalities/unwind/standard/TestStandardUnwind.py

def standard_unwind_tests (self):
 
         triple = self.dbg.GetSelectedPlatform().GetTriple()
         if re.match("arm-.*-.*-android", triple):
             base_function_names = [
                 "_start",                # Base function on the stack
                 "__memcpy_base",         # Function reached by a fall through from the previous function
                 "__memcpy_base_aligned", # Function reached by a fall through from the previous function
                 "__subdf3",              # __aeabi_ui2d jumps into the middle of the function. Possibly missing symbol?
-                "__aeabi_ldivmod",       # llvm.org/pr23879 ("push {sp}" not handled correctly)
-                "__aeabi_uldivmod",      # llvm.org/pr23879 ("push {sp}" not handled correctly)
             ]
             no_step_function_names = [
                 "__sync_fetch_and_add_4", # Calls into a special SO where we can't set a breakpoint
                 "pthread_mutex_lock",     # Uses ldrex and strex what interferes with the software single stepping
                 "pthread_mutex_unlock",   # Uses ldrex and strex what interferes with the software single stepping
                 "pthread_once",           # Uses ldrex and strex what interferes with the software single stepping
             ]
         elif re.match("aarch64-.*-.*-android", triple):

test/functionalities/unwind/standard/hand_written/divmod.cpp

+//===-- divmod.cpp ----------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+int
+main(int argc, char const *argv[])
+{
+    signed long long a = 123456789, b = 12, c = a / b, d = a % b;
+    unsigned long long e = 123456789, f = 12, g = e / f, h = e % f;
+}