Expression evaluation, a new ThreadPlanCallFunctionUsingABI for executing a function call on target via register manipulation

For Hexagon we want to be able to call functions during debugging, however currently lldb only supports this when there is JIT support. 
Although emulation using IR interpretation is an alternative, it is currently limited in that it can't make function calls.

In this patch we have extended the IR interpreter so that it can execute a function call on the target using register manipulation. 
To do this we need to handle the Call IR instruction, passing arguments to a new thread plan and collecting any return values to pass back into the IR interpreter. 

The new thread plan is needed to call an alternative ABI interface of "ABI::PerpareTrivialCall()", allowing more detailed information about arguments and return values.

Reviewers: jingham, spyffe

Subscribers: emaste, lldb-commits, ted, ADodds, deepak2427

Differential Revision: http://reviews.llvm.org/D9404

llvm-svn: 242137

1 files changed, 252 insertions, 25 deletions

diff --git a/lldb/source/Expression/IRInterpreter.cpp b/lldb/source/Expression/IRInterpreter.cpp
index d11bdc1671b..926d1f22b6a 100644
--- a/lldb/source/Expression/IRInterpreter.cpp
+++ b/lldb/source/Expression/IRInterpreter.cpp
@@ -10,17 +10,28 @@
 #include "lldb/Core/DataExtractor.h"
 #include "lldb/Core/Error.h"
 #include "lldb/Core/Log.h"
+#include "lldb/Core/ModuleSpec.h"
+#include "lldb/Core/Module.h"
 #include "lldb/Core/Scalar.h"
 #include "lldb/Core/StreamString.h"
+#include "lldb/Core/ValueObject.h"
 #include "lldb/Expression/IRMemoryMap.h"
 #include "lldb/Expression/IRInterpreter.h"
 #include "lldb/Host/Endian.h"
 
+#include "lldb/Target/ABI.h"
+#include "lldb/Target/ExecutionContext.h"
+#include "lldb/Target/Target.h"
+#include "lldb/Target/Thread.h"
+#include "lldb/Target/ThreadPlan.h"
+#include "lldb/Target/ThreadPlanCallFunctionUsingABI.h"
+
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/Intrinsics.h"
+#include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
 #include "llvm/Support/raw_ostream.h"
 
@@ -455,7 +466,8 @@ static const char *infinite_loop_error              = "Interpreter ran for too m
 bool
 IRInterpreter::CanInterpret (llvm::Module &module,
                              llvm::Function &function,
-                             lldb_private::Error &error)
+                             lldb_private::Error &error,
+                             const bool support_function_calls)
 {
     lldb_private::Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_EXPRESSIONS));
 
@@ -507,7 +519,7 @@ IRInterpreter::CanInterpret (llvm::Module &module,
                         return false;
                     }
 
-                    if (!CanIgnoreCall(call_inst))
+                    if (!CanIgnoreCall(call_inst) && !support_function_calls)
                     {
                         if (log)
                             log->Printf("Unsupported instruction: %s", PrintValue(ii).c_str());
@@ -611,7 +623,8 @@ IRInterpreter::Interpret (llvm::Module &module,
                           lldb_private::IRMemoryMap &memory_map,
                           lldb_private::Error &error,
                           lldb::addr_t stack_frame_bottom,
-                          lldb::addr_t stack_frame_top)
+                          lldb::addr_t stack_frame_top,
+                          lldb_private::ExecutionContext &exe_ctx)
 {
     lldb_private::Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_EXPRESSIONS));
 
@@ -668,29 +681,7 @@ IRInterpreter::Interpret (llvm::Module &module,
         {
             default:
                 break;
-            case Instruction::Call:
-            {
-                const CallInst *call_inst = dyn_cast<CallInst>(inst);
-
-                if (!call_inst)
-                {
-                    if (log)
-                        log->Printf("getOpcode() returns %s, but instruction is not a CallInst", inst->getOpcodeName());
-                    error.SetErrorToGenericError();
-                    error.SetErrorString(interpreter_internal_error);
-                    return false;
-                }
 
-                if (!CanIgnoreCall(call_inst))
-                {
-                    if (log)
-                        log->Printf("The interpreter shouldn't have accepted %s", PrintValue(call_inst).c_str());
-                    error.SetErrorToGenericError();
-                    error.SetErrorString(interpreter_internal_error);
-                    return false;
-                }
-            }
-                break;
             case Instruction::Add:
             case Instruction::Sub:
             case Instruction::Mul:
@@ -1476,6 +1467,242 @@ IRInterpreter::Interpret (llvm::Module &module,
                 }
             }
                 break;
+            case Instruction::Call:
+            {
+                const CallInst *call_inst = dyn_cast<CallInst>(inst);
+
+                if (!call_inst)
+                {
+                    if (log)
+                       log->Printf("getOpcode() returns %s, but instruction is not a CallInst", inst->getOpcodeName());
+                    error.SetErrorToGenericError();
+                    error.SetErrorString(interpreter_internal_error);
+                    return false;
+                }
+
+                if (CanIgnoreCall(call_inst))
+                    break;
+
+                // Get the return type
+                llvm::Type *returnType = call_inst->getType();
+                if (returnType == nullptr)
+                {
+                    error.SetErrorToGenericError();
+                    error.SetErrorString("unable to access return type");
+                    return false;
+                }
+
+                // Work with void, integer and pointer return types
+                if (!returnType->isVoidTy() &&
+                    !returnType->isIntegerTy() &&
+                    !returnType->isPointerTy())
+                {
+                    error.SetErrorToGenericError();
+                    error.SetErrorString("return type is not supported");
+                    return false;
+                }
+
+                // Check we can actually get a thread
+                if (exe_ctx.GetThreadPtr() == nullptr)
+                {
+                    error.SetErrorToGenericError();
+                    error.SetErrorStringWithFormat("unable to acquire thread");
+                    return false;
+                }
+
+                // Make sure we have a valid process
+                if (!exe_ctx.GetProcessPtr())
+                {
+                    error.SetErrorToGenericError();
+                    error.SetErrorStringWithFormat("unable to get the process");
+                    return false;
+                }
+
+                // Find the address of the callee function
+                lldb_private::Scalar I;
+                const llvm::Value *val = call_inst->getCalledValue();
+
+                if (!frame.EvaluateValue(I, val, module))
+                {
+                    error.SetErrorToGenericError();
+                    error.SetErrorString("unable to get address of function");
+                    return false;
+                }
+                lldb_private::Address funcAddr(I.ULongLong(LLDB_INVALID_ADDRESS));
+
+                lldb_private::StreamString error_stream;
+                lldb_private::EvaluateExpressionOptions options;
+
+                // We generally receive a function pointer which we must dereference
+                llvm::Type* prototype = val->getType();
+                if (!prototype->isPointerTy())
+                {
+                    error.SetErrorToGenericError();
+                    error.SetErrorString("call need function pointer");
+                    return false;
+                }
+
+                // Dereference the function pointer
+                prototype = prototype->getPointerElementType();
+                if (!(prototype->isFunctionTy() || prototype->isFunctionVarArg()))
+                {
+                    error.SetErrorToGenericError();
+                    error.SetErrorString("call need function pointer");
+                    return false;
+                }
+
+                // Find number of arguments
+                const int numArgs = call_inst->getNumArgOperands();
+
+                // We work with a fixed array of 16 arguments which is our upper limit
+                static lldb_private::ABI::CallArgument rawArgs[16];
+                if (numArgs >= 16)
+                {
+                    error.SetErrorToGenericError();
+                    error.SetErrorStringWithFormat("function takes too many arguments");
+                    return false;
+                }
+
+                // Push all function arguments to the argument list that will
+                // be passed to the call function thread plan
+                for (int i = 0; i < numArgs; i++)
+                {
+                    // Get details of this argument
+                    llvm::Value *arg_op = call_inst->getArgOperand(i);
+                    llvm::Type  *arg_ty = arg_op->getType();
+
+                    // Ensure that this argument is an supported type
+                    if (!arg_ty->isIntegerTy() && !arg_ty->isPointerTy())
+                    {
+                         error.SetErrorToGenericError();
+                         error.SetErrorStringWithFormat("argument %d must be integer type", i);
+                         return false;
+                    }
+
+                    // Extract the arguments value
+                    lldb_private::Scalar tmp_op = 0;
+                    if (!frame.EvaluateValue(tmp_op, arg_op, module))
+                    {
+                         error.SetErrorToGenericError();
+                         error.SetErrorStringWithFormat("unable to evaluate argument %d", i);
+                         return false;
+                    }
+
+                    // Check if this is a string literal or constant string pointer
+                    if (arg_ty->isPointerTy())
+                    {
+                        // Pointer to just one type
+                        assert(arg_ty->getNumContainedTypes() == 1);
+
+                        lldb::addr_t addr = tmp_op.ULongLong();
+                        size_t dataSize = 0;
+
+                        if (memory_map.GetAllocSize(addr, dataSize))
+                        {
+                            // Create the required buffer
+                            rawArgs[i].size = dataSize;
+                            rawArgs[i].data_ap.reset(new uint8_t[dataSize + 1]);
+
+                            // Read string from host memory
+                            memory_map.ReadMemory(rawArgs[i].data_ap.get(), addr, dataSize, error);
+                            if (error.Fail())
+                            {
+                                assert(!"we have failed to read the string from memory");
+                                return false;
+                            }
+                            // Add null terminator
+                            rawArgs[i].data_ap[dataSize] = '\0';
+                            rawArgs[i].type = lldb_private::ABI::CallArgument::HostPointer;
+                        }
+                        else
+                        {
+                            assert(!"unable to locate host data for transfer to device");
+                            return false;
+                        }
+                    }
+                    else /* if ( arg_ty->isPointerTy() ) */
+                    {
+                        rawArgs[i].type = lldb_private::ABI::CallArgument::TargetValue;
+                        // Get argument size in bytes
+                        rawArgs[i].size = arg_ty->getIntegerBitWidth() / 8;
+                        // Push value into argument list for thread plan
+                        rawArgs[i].value = tmp_op.ULongLong();
+                    }
+
+                }
+
+                // Pack the arguments into an llvm::array
+                llvm::ArrayRef<lldb_private::ABI::CallArgument> args(rawArgs, numArgs);
+
+                // Setup a thread plan to call the target function
+                lldb::ThreadPlanSP call_plan_sp
+                (
+                    new lldb_private::ThreadPlanCallFunctionUsingABI
+                    (
+                        exe_ctx.GetThreadRef(),
+                        funcAddr,
+                        *prototype,
+                        *returnType,
+                        args,
+                        options
+                    )
+                );
+
+                // Check if the plan is valid
+                if (!call_plan_sp || !call_plan_sp->ValidatePlan(&error_stream))
+                {
+                    error.SetErrorToGenericError();
+                    error.SetErrorStringWithFormat("unable to make ThreadPlanCallFunctionUsingABI for 0x%llx", I.ULongLong());
+                    return false;
+                }
+
+                exe_ctx.GetProcessPtr()->SetRunningUserExpression(true);
+
+                // Execute the actual function call thread plan
+                lldb::ExpressionResults res = exe_ctx.GetProcessRef().RunThreadPlan(exe_ctx, call_plan_sp, options, error_stream);
+
+                // Check that the thread plan completed successfully
+                if (res != lldb::ExpressionResults::eExpressionCompleted)
+                {
+                    error.SetErrorToGenericError();
+                    error.SetErrorStringWithFormat("ThreadPlanCallFunctionUsingABI failed");
+                    return false;
+                }
+
+                exe_ctx.GetProcessPtr()->SetRunningUserExpression(false);
+
+                // Void return type
+                if (returnType->isVoidTy())
+                {
+                    // Cant assign to void types, so we leave the frame untouched
+                }
+                else
+                    // Integer or pointer return type
+                    if (returnType->isIntegerTy() || returnType->isPointerTy())
+                    {
+                        // Get the encapsulated return value
+                        lldb::ValueObjectSP retVal = call_plan_sp.get()->GetReturnValueObject();
+
+                        lldb_private::Scalar returnVal = -1;
+                        lldb_private::ValueObject *vobj = retVal.get();
+
+                        // Check if the return value is valid
+                        if (vobj == nullptr || retVal.empty())
+                        {
+                            error.SetErrorToGenericError();
+                            error.SetErrorStringWithFormat("unable to get the return value");
+                            return false;
+                        }
+
+                        // Extract the return value as a integer
+                        lldb_private::Value & value = vobj->GetValue();
+                        returnVal = value.GetScalar();
+
+                        // Push the return value as the result
+                        frame.AssignValue(inst, returnVal, module);
+                    }
+            }
+                break;
         }
 
         ++frame.m_ii;