[MIPS] Use Address::GetAddressClass() instead of elf flags to decide address space of an address

[bhushan]

Summary

In MIPS, an application elf can contain mixed code (mips + micromips) i.e some functions in the application can be "micromips" and some functions can be MIPS-only (non-micromips).
Micromips functions has compressed addresses (bit #0 set) and MIPS functions has un-compressed addresses (bit #0 clear).
Such mixed-mode elf will have micromips specific bits set in its flags. That means "IsMicromips" will be true even for non-micromips address.

This patch fixes this by using Address::GetAddressClass() to decide which address space the address belongs to (instead of deciding this from elf's flags).

[clayborg]

Back from vacation, sorry for the delay. Looks good.

[zturner]

You should add a test for this. You might need a @skipIfNotMips decorator

[Eugene.Zelenko]

Looks like patch was not committed.

[bhushan]

Hi Eugene,

I did not commit this patch because @zturner had asked for a testcase for this change. But the test will require to build it for micromips target (-mmicromips option) and currently I don't have any micromips hardware available. I had tested this patch with simulator.

I can rebase and commit it if @clayborg and @zturner agrees.

source/Target/Target.cpp

Target::GetBreakableLoadAddress (lldb::addr_t addr)
     case llvm::Triple::mips64:
     case llvm::Triple::mips64el:
     {
         addr_t function_start = 0;
         addr_t current_offset = 0;
         uint32_t loop_count = 0;
         Address resolved_addr;
         uint32_t arch_flags = m_arch.GetFlags ();
-        bool IsMips16 = arch_flags & ArchSpec::eMIPSAse_mips16;
-        bool IsMicromips = arch_flags & ArchSpec::eMIPSAse_micromips;
         SectionLoadList &section_load_list = GetSectionLoadList();
 
+        // Get opcode address
+        addr = GetOpcodeLoadAddress (addr, eAddressClassCode);
+        breakable_addr = addr;
+
         if (section_load_list.IsEmpty())
             // No sections are loaded, so we must assume we are not running yet
             // and need to operate only on file address.
             m_images.ResolveFileAddress (addr, resolved_addr); 
         else
             section_load_list.ResolveLoadAddress(addr, resolved_addr);
 
         // Get the function boundaries to make sure we don't scan back before the beginning of the current function.
case llvm::Triple::mips64el:
         if (current_offset == 0)
             return breakable_addr;
         else
             loop_count = current_offset / 2;
 
         if (loop_count > 3)
         {
             // Scan previous 6 bytes
-            if (IsMips16 | IsMicromips)
+            if (resolved_addr.GetAddressClass() == eAddressClassCodeAlternateISA)
                 loop_count = 3;
             // For mips-only, instructions are always 4 bytes, so scan previous 4 bytes only.
             else
                 loop_count = 2;
         }
 
         // Create Disassembler Instance
         lldb::DisassemblerSP disasm_sp (Disassembler::FindPlugin(m_arch, NULL, NULL));