[Lldb-commits] [lldb] r151953 - /lldb/trunk/source/Plugins/Disassembler/llvm/DisassemblerLLVMC.cpp

[Chris Lattner]

On Mar 2, 2012, at 3:22 PM, Sean Callanan wrote:

> Author: spyffe
> Date: Fri Mar  2 17:22:53 2012
> New Revision: 151953
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=151953&view=rev
> Log:
> Added a function to the disassembler that checks
> (from the mnemonic) whether an instruction is a
> branch.  This function's result is exposed through
> DoesBranch().

hi Sean,

The m_disasm.GetArchitecture().GetMachine(); call isn't very fast. Is there a way to get (and cache) this enum at a higher level?  Is there a way to propagate the "isBranch" information that the MC tables already know up through these APIs?

-Chris

> 
> Modified:
>    lldb/trunk/source/Plugins/Disassembler/llvm/DisassemblerLLVMC.cpp
> 
> Modified: lldb/trunk/source/Plugins/Disassembler/llvm/DisassemblerLLVMC.cpp
> URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Plugins/Disassembler/llvm/DisassemblerLLVMC.cpp?rev=151953&r1=151952&r2=151953&view=diff
> ==============================================================================
> --- lldb/trunk/source/Plugins/Disassembler/llvm/DisassemblerLLVMC.cpp (original)
> +++ lldb/trunk/source/Plugins/Disassembler/llvm/DisassemblerLLVMC.cpp Fri Mar  2 17:22:53 2012
> @@ -37,7 +37,8 @@
>         m_disasm(disasm),
>         m_is_valid(false),
>         m_no_comments(true),
> -        m_comment_stream()
> +        m_comment_stream(),
> +        m_does_branch(eLazyBoolCalculate)
>     {
>     }
> 
> @@ -147,7 +148,7 @@
>     virtual bool
>     DoesBranch () const
>     {
> -        return false;
> +        return m_does_branch == eLazyBoolYes;
>     }
> 
>     virtual size_t
> @@ -251,6 +252,90 @@
>         }
>     }
> 
> +    bool StringRepresentsBranch (const char *data, size_t size)
> +    {
> +        const char *cursor = data;
> +
> +        bool inWhitespace = true;
> +
> +        while (inWhitespace && cursor < data + size)
> +        {
> +            switch (*cursor)
> +            {
> +            default:
> +                inWhitespace = false;
> +                break;
> +            case ' ':
> +                break;
> +            case '\t':
> +                break;
> +            }
> +            
> +            if (inWhitespace)
> +                ++cursor;
> +        }
> +        
> +        if (cursor >= data + size)
> +            return false;
> +        
> +        llvm::Triple::ArchType arch = m_disasm.GetArchitecture().GetMachine();
> +        
> +        switch (arch)
> +        {
> +        default:
> +            return false;
> +        case llvm::Triple::x86:
> +        case llvm::Triple::x86_64:
> +            switch (cursor[0])
> +            {
> +            default:
> +                return false;
> +            case 'j':
> +                return true;
> +            case 'c':
> +                if (cursor[1] == 'a' &&
> +                    cursor[2] == 'l' &&
> +                    cursor[3] == 'l')
> +                    return true;
> +                else
> +                    return false;
> +            }
> +        case llvm::Triple::arm:
> +        case llvm::Triple::thumb:
> +            switch (cursor[0])
> +            {
> +            default:
> +                return false;
> +            case 'b':
> +                {
> +                    switch (cursor[1])
> +                    {
> +                    default:
> +                        return false;
> +                    case 'l':
> +                    case 'x':
> +                    case ' ':
> +                    case '\t':
> +                        return true;
> +                    }
> +                    return false;
> +                }
> +            case 'c':
> +                {
> +                    switch (cursor[1])
> +                    {
> +                    default:
> +                        return false;
> +                    case 'b':
> +                        return true;
> +                    }
> +                }
> +            }
> +        }
> +        
> +        return false;
> +    }
> +    
>     template <bool Reparse> bool Parse (const lldb_private::Address &address, 
>                                         lldb_private::AddressClass addr_class,
>                                         const DataExtractor &extractor,
> @@ -279,6 +364,10 @@
>                                                    out_string.data(), 
>                                                    out_string.size());
> 
> +        if (m_does_branch == eLazyBoolCalculate)
> +            m_does_branch = (StringRepresentsBranch (out_string.data(), out_string.size()) ?
> +                             eLazyBoolYes : eLazyBoolNo);
> +        
>         m_comment_stream.Flush();
>         m_no_comments = false;
> 
> @@ -331,6 +420,7 @@
> 
>     bool                    m_no_comments;
>     StreamString            m_comment_stream;
> +    LazyBool                m_does_branch;
> 
>     static bool             s_regex_compiled;
>     static ::regex_t        s_regex;
> 
> 
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