[Lldb-commits] [PATCH] D19124: [LLDB] Added support for PHI nodes to IR interpreter

[Zachary Turner via lldb-commits]

I'll let Sean comment on the content of the patch, but please add a test
that runs such an expression and demonstrates the correct output.

On Thu, Apr 14, 2016 at 10:01 AM Cameron via lldb-commits <
lldb-commits at lists.llvm.org> wrote:

> cameron314 created this revision.
> cameron314 added a reviewer: spyffe.
> cameron314 added subscribers: mamai, lldb-commits.
> cameron314 set the repository for this revision to rL LLVM.
>
> This allows expressions such as 'i == 1 || i == 2` to be executed using
> the IR interpreter.
>
> Repository:
>   rL LLVM
>
> http://reviews.llvm.org/D19124
>
> Files:
>   source/Expression/IRInterpreter.cpp
>
> Index: source/Expression/IRInterpreter.cpp
> ===================================================================
> --- source/Expression/IRInterpreter.cpp
> +++ source/Expression/IRInterpreter.cpp
> @@ -106,6 +106,7 @@
>      DataLayout                             &m_target_data;
>      lldb_private::IRExecutionUnit          &m_execution_unit;
>      const BasicBlock                       *m_bb;
> +    const BasicBlock                       *m_prev_bb;
>      BasicBlock::const_iterator              m_ii;
>      BasicBlock::const_iterator              m_ie;
>
> @@ -121,7 +122,9 @@
>                             lldb::addr_t stack_frame_bottom,
>                             lldb::addr_t stack_frame_top) :
>          m_target_data (target_data),
> -        m_execution_unit (execution_unit)
> +        m_execution_unit (execution_unit),
> +        m_bb (nullptr),
> +        m_prev_bb (nullptr)
>      {
>          m_byte_order = (target_data.isLittleEndian() ?
> lldb::eByteOrderLittle : lldb::eByteOrderBig);
>          m_addr_byte_size = (target_data.getPointerSize(0));
> @@ -137,6 +140,7 @@
>
>      void Jump (const BasicBlock *bb)
>      {
> +        m_prev_bb = m_bb;
>          m_bb = bb;
>          m_ii = m_bb->begin();
>          m_ie = m_bb->end();
> @@ -563,6 +567,7 @@
>              case Instruction::Alloca:
>              case Instruction::BitCast:
>              case Instruction::Br:
> +            case Instruction::PHI:
>                  break;
>              case Instruction::Call:
>                  {
> @@ -1052,6 +1057,46 @@
>                  }
>              }
>                  continue;
> +            case Instruction::PHI:
> +            {
> +                const PHINode *phi_inst = dyn_cast<PHINode>(inst);
> +
> +                if (!phi_inst)
> +                {
> +                    if (log)
> +                        log->Printf("getOpcode() returns PHI, but
> instruction is not a PHINode");
> +                    error.SetErrorToGenericError();
> +                    error.SetErrorString(interpreter_internal_error);
> +                    return false;
> +                }
> +                if (!frame.m_prev_bb)
> +                {
> +                    if (log)
> +                        log->Printf("Encountered PHI node without having
> jumped from another basic block");
> +                    error.SetErrorToGenericError();
> +                    error.SetErrorString(interpreter_internal_error);
> +                    return false;
> +                }
> +
> +                Value* value =
> phi_inst->getIncomingValueForBlock(frame.m_prev_bb);
> +                lldb_private::Scalar result;
> +                if (!frame.EvaluateValue(result, value, module))
> +                {
> +                    if (log)
> +                        log->Printf("Couldn't evaluate %s",
> PrintValue(value).c_str());
> +                    error.SetErrorToGenericError();
> +                    error.SetErrorString(bad_value_error);
> +                    return false;
> +                }
> +                frame.AssignValue(inst, result, module);
> +
> +                if (log)
> +                {
> +                    log->Printf("Interpreted a %s",
> inst->getOpcodeName());
> +                    log->Printf("  Incoming value : %s",
> frame.SummarizeValue(value).c_str());
> +                }
> +            }
> +            break;
>              case Instruction::GetElementPtr:
>              {
>                  const GetElementPtrInst *gep_inst =
> dyn_cast<GetElementPtrInst>(inst);
>
>
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