Add the infrastructure to test instruction emulations automatically.

The idea is that the instruction to be emulated is actually executed
on the hardware to be emulated, with the before and after state of the
hardware being captured and 'freeze-dried' into .dat files.  The
emulation testing code then loads the before & after state from the
.dat file, emulates the instruction using the before state, and
compares the resulting state to the 'after' state.  If they match, the
emulation is accurate, otherwise there is a problem.

The final format of the .dat files needs a bit more work; the plan is
to generalize them a bit and to convert the plain values to key-value pairs. 
But I wanted to get this first pass committed.

This commit adds arm instruction emulation testing to the testsuite, along with
many initial .dat files.

It also fixes a bug in the llvm disassembler, where 32-bit thumb opcodes
were getting their upper & lower 16-bits reversed.

There is a new Instruction sub-class, that is intended to be loaded
from a .dat file rather than read from an executable.  There is also a
new EmulationStateARM class, for handling the before & after states.
EmulationStates for other architetures can be added later when we
emulate their instructions.

llvm-svn: 129832

1 files changed, 13 insertions, 1 deletions

diff --git a/lldb/source/Plugins/Disassembler/llvm/DisassemblerLLVM.cpp b/lldb/source/Plugins/Disassembler/llvm/DisassemblerLLVM.cpp
index 5ddcd727bc0..23a788b16b5 100644
--- a/lldb/source/Plugins/Disassembler/llvm/DisassemblerLLVM.cpp
+++ b/lldb/source/Plugins/Disassembler/llvm/DisassemblerLLVM.cpp
@@ -367,7 +367,19 @@ InstructionLLVM::Decode (const Disassembler &disassembler,
                 break;
 
             case 4:
-                m_opcode.SetOpcode32 (data.GetU32 (&offset));
+                {
+                if (GetAddressClass() ==  eAddressClassCodeAlternateISA)
+                {
+                    // If it is a 32-bit THUMB instruction, we need to swap the upper & lower halves.
+                    uint32_t orig_bytes = data.GetU32 (&offset);
+                    uint16_t upper_bits = (orig_bytes >> 16) & ((1u << 16) - 1);
+                    uint16_t lower_bits = orig_bytes & ((1u << 16) - 1);
+                    uint32_t swapped = (lower_bits << 16) | upper_bits;
+                    m_opcode.SetOpcode32 (swapped);
+                }
+                else
+                    m_opcode.SetOpcode32 (data.GetU32 (&offset));
+                }
                 break;
 
             default: