/usr/lib/llvm-3.4/include/lldb/Expression/IRForTarget.h is in liblldb-3.4-dev 1:3.4.2-13.
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//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef liblldb_IRForTarget_h_
#define liblldb_IRForTarget_h_
#include "lldb/lldb-public.h"
#include "lldb/Core/ConstString.h"
#include "lldb/Core/Error.h"
#include "lldb/Core/Stream.h"
#include "lldb/Core/StreamString.h"
#include "lldb/Symbol/TaggedASTType.h"
#include "llvm/Pass.h"
#include <map>
#include <functional>
namespace llvm {
class BasicBlock;
class CallInst;
class Constant;
class ConstantInt;
class Function;
class GlobalValue;
class GlobalVariable;
class Instruction;
class Module;
class StoreInst;
class DataLayout;
class Type;
class Value;
}
namespace lldb_private {
class ClangExpressionDeclMap;
class IRExecutionUnit;
class IRMemoryMap;
}
//----------------------------------------------------------------------
/// @class IRForTarget IRForTarget.h "lldb/Expression/IRForTarget.h"
/// @brief Transforms the IR for a function to run in the target
///
/// Once an expression has been parsed and converted to IR, it can run
/// in two contexts: interpreted by LLDB as a DWARF location expression,
/// or compiled by the JIT and inserted into the target process for
/// execution.
///
/// IRForTarget makes the second possible, by applying a series of
/// transformations to the IR which make it relocatable. These
/// transformations are discussed in more detail next to their relevant
/// functions.
//----------------------------------------------------------------------
class IRForTarget : public llvm::ModulePass
{
public:
//------------------------------------------------------------------
/// Constructor
///
/// @param[in] decl_map
/// The list of externally-referenced variables for the expression,
/// for use in looking up globals and allocating the argument
/// struct. See the documentation for ClangExpressionDeclMap.
///
/// @param[in] resolve_vars
/// True if the external variable references (including persistent
/// variables) should be resolved. If not, only external functions
/// are resolved.
///
/// @param[in] execution_policy
/// Determines whether an IR interpreter can be used to statically
/// evaluate the expression.
///
/// @param[in] const_result
/// This variable is populated with the statically-computed result
/// of the function, if it has no side-effects and the result can
/// be computed statically.
///
/// @param[in] execution_unit
/// The holder for raw data associated with the expression.
///
/// @param[in] error_stream
/// If non-NULL, a stream on which errors can be printed.
///
/// @param[in] func_name
/// The name of the function to prepare for execution in the target.
//------------------------------------------------------------------
IRForTarget(lldb_private::ClangExpressionDeclMap *decl_map,
bool resolve_vars,
lldb_private::IRExecutionUnit &execution_unit,
lldb_private::Stream *error_stream,
const char* func_name = "$__lldb_expr");
//------------------------------------------------------------------
/// Destructor
//------------------------------------------------------------------
virtual ~IRForTarget();
//------------------------------------------------------------------
/// Run this IR transformer on a single module
///
/// Implementation of the llvm::ModulePass::runOnModule() function.
///
/// @param[in] llvm_module
/// The module to run on. This module is searched for the function
/// $__lldb_expr, and that function is passed to the passes one by
/// one.
///
/// @param[in] interpreter_error
/// An error. If the expression fails to be interpreted, this error
/// is set to a reason why.
///
/// @return
/// True on success; false otherwise
//------------------------------------------------------------------
virtual bool
runOnModule (llvm::Module &llvm_module);
//------------------------------------------------------------------
/// Interface stub
///
/// Implementation of the llvm::ModulePass::assignPassManager()
/// function.
//------------------------------------------------------------------
virtual void
assignPassManager (llvm::PMStack &pass_mgr_stack,
llvm::PassManagerType pass_mgr_type = llvm::PMT_ModulePassManager);
//------------------------------------------------------------------
/// Returns PMT_ModulePassManager
///
/// Implementation of the llvm::ModulePass::getPotentialPassManagerType()
/// function.
//------------------------------------------------------------------
virtual llvm::PassManagerType
getPotentialPassManagerType() const;
private:
//------------------------------------------------------------------
/// Ensures that the current function's linkage is set to external.
/// Otherwise the JIT may not return an address for it.
///
/// @param[in] llvm_function
/// The function whose linkage is to be fixed.
///
/// @return
/// True on success; false otherwise.
//------------------------------------------------------------------
bool
FixFunctionLinkage (llvm::Function &llvm_function);
//------------------------------------------------------------------
/// A module-level pass to replace all function pointers with their
/// integer equivalents.
//------------------------------------------------------------------
//------------------------------------------------------------------
/// The top-level pass implementation
///
/// @param[in] llvm_module
/// The module currently being processed.
///
/// @param[in] llvm_function
/// The function currently being processed.
///
/// @return
/// True on success; false otherwise.
//------------------------------------------------------------------
bool
HasSideEffects (llvm::Function &llvm_function);
//------------------------------------------------------------------
/// A function-level pass to check whether the function has side
/// effects.
//------------------------------------------------------------------
//------------------------------------------------------------------
/// Get the address of a fuction, and a location to put the complete
/// Value of the function if one is available.
///
/// @param[in] function
/// The function to find the location of.
///
/// @param[out] ptr
/// The location of the function in the target.
///
/// @param[out] name
/// The resolved name of the function (matters for intrinsics).
///
/// @param[out] value_ptr
/// A variable to put the function's completed Value* in, or NULL
/// if the Value* shouldn't be stored anywhere.
///
/// @return
/// The pointer.
//------------------------------------------------------------------
bool
GetFunctionAddress (llvm::Function *function,
uint64_t &ptr,
lldb_private::ConstString &name,
llvm::Constant **&value_ptr);
//------------------------------------------------------------------
/// Build a function pointer given a type and a raw pointer.
///
/// @param[in] type
/// The type of the function pointer to be built.
///
/// @param[in] ptr
/// The value of the pointer.
///
/// @return
/// The pointer.
//------------------------------------------------------------------
llvm::Constant *
BuildFunctionPointer (llvm::Type *type,
uint64_t ptr);
void
RegisterFunctionMetadata (llvm::LLVMContext &context,
llvm::Value *function_ptr,
const char *name);
//------------------------------------------------------------------
/// The top-level pass implementation
///
/// @param[in] llvm_function
/// The function currently being processed.
///
/// @return
/// True if the function has side effects (or if this cannot
/// be determined); false otherwise.
//------------------------------------------------------------------
bool
ResolveFunctionPointers (llvm::Module &llvm_module);
//------------------------------------------------------------------
/// A function-level pass to take the generated global value
/// $__lldb_expr_result and make it into a persistent variable.
/// Also see ASTResultSynthesizer.
//------------------------------------------------------------------
//------------------------------------------------------------------
/// Find the NamedDecl corresponding to a Value. This interface is
/// exposed for the IR interpreter.
///
/// @param[in] module
/// The module containing metadata to search
///
/// @param[in] global
/// The global entity to search for
///
/// @return
/// The corresponding variable declaration
//------------------------------------------------------------------
public:
static clang::NamedDecl *
DeclForGlobal (const llvm::GlobalValue *global_val, llvm::Module *module);
private:
clang::NamedDecl *
DeclForGlobal (llvm::GlobalValue *global);
//------------------------------------------------------------------
/// Set the constant result variable m_const_result to the provided
/// constant, assuming it can be evaluated. The result variable
/// will be reset to NULL later if the expression has side effects.
///
/// @param[in] initializer
/// The constant initializer for the variable.
///
/// @param[in] name
/// The name of the result variable.
///
/// @param[in] type
/// The Clang type of the result variable.
//------------------------------------------------------------------
void
MaybeSetConstantResult (llvm::Constant *initializer,
const lldb_private::ConstString &name,
lldb_private::TypeFromParser type);
//------------------------------------------------------------------
/// If the IR represents a cast of a variable, set m_const_result
/// to the result of the cast. The result variable will be reset to
/// NULL latger if the expression has side effects.
///
/// @param[in] type
/// The Clang type of the result variable.
//------------------------------------------------------------------
void
MaybeSetCastResult (lldb_private::TypeFromParser type);
//------------------------------------------------------------------
/// The top-level pass implementation
///
/// @param[in] llvm_function
/// The function currently being processed.
///
/// @return
/// True on success; false otherwise
//------------------------------------------------------------------
bool
CreateResultVariable (llvm::Function &llvm_function);
//------------------------------------------------------------------
/// A module-level pass to find Objective-C constant strings and
/// transform them to calls to CFStringCreateWithBytes.
//------------------------------------------------------------------
//------------------------------------------------------------------
/// Rewrite a single Objective-C constant string.
///
/// @param[in] NSStr
/// The constant NSString to be transformed
///
/// @param[in] CStr
/// The constant C string inside the NSString. This will be
/// passed as the bytes argument to CFStringCreateWithBytes.
///
/// @return
/// True on success; false otherwise
//------------------------------------------------------------------
bool
RewriteObjCConstString (llvm::GlobalVariable *NSStr,
llvm::GlobalVariable *CStr);
//------------------------------------------------------------------
/// The top-level pass implementation
///
/// @return
/// True on success; false otherwise
//------------------------------------------------------------------
bool
RewriteObjCConstStrings ();
//------------------------------------------------------------------
/// A basic block-level pass to find all Objective-C method calls and
/// rewrite them to use sel_registerName instead of statically allocated
/// selectors. The reason is that the selectors are created on the
/// assumption that the Objective-C runtime will scan the appropriate
/// section and prepare them. This doesn't happen when code is copied
/// into the target, though, and there's no easy way to induce the
/// runtime to scan them. So instead we get our selectors from
/// sel_registerName.
//------------------------------------------------------------------
//------------------------------------------------------------------
/// Replace a single selector reference
///
/// @param[in] selector_load
/// The load of the statically-allocated selector.
///
/// @return
/// True on success; false otherwise
//------------------------------------------------------------------
bool
RewriteObjCSelector (llvm::Instruction* selector_load);
//------------------------------------------------------------------
/// The top-level pass implementation
///
/// @param[in] basic_block
/// The basic block currently being processed.
///
/// @return
/// True on success; false otherwise
//------------------------------------------------------------------
bool
RewriteObjCSelectors (llvm::BasicBlock &basic_block);
//------------------------------------------------------------------
/// A basic block-level pass to find all newly-declared persistent
/// variables and register them with the ClangExprDeclMap. This
/// allows them to be materialized and dematerialized like normal
/// external variables. Before transformation, these persistent
/// variables look like normal locals, so they have an allocation.
/// This pass excises these allocations and makes references look
/// like external references where they will be resolved -- like all
/// other external references -- by ResolveExternals().
//------------------------------------------------------------------
//------------------------------------------------------------------
/// Handle a single allocation of a persistent variable
///
/// @param[in] persistent_alloc
/// The allocation of the persistent variable.
///
/// @return
/// True on success; false otherwise
//------------------------------------------------------------------
bool
RewritePersistentAlloc (llvm::Instruction *persistent_alloc);
//------------------------------------------------------------------
/// The top-level pass implementation
///
/// @param[in] basic_block
/// The basic block currently being processed.
//------------------------------------------------------------------
bool
RewritePersistentAllocs (llvm::BasicBlock &basic_block);
//------------------------------------------------------------------
/// A function-level pass to find all external variables and functions
/// used in the IR. Each found external variable is added to the
/// struct, and each external function is resolved in place, its call
/// replaced with a call to a function pointer whose value is the
/// address of the function in the target process.
//------------------------------------------------------------------
//------------------------------------------------------------------
/// Write an initializer to a memory array of assumed sufficient
/// size.
///
/// @param[in] data
/// A pointer to the data to write to.
///
/// @param[in] initializer
/// The initializer itself.
///
/// @return
/// True on success; false otherwise
//------------------------------------------------------------------
bool
MaterializeInitializer (uint8_t *data, llvm::Constant *initializer);
//------------------------------------------------------------------
/// Move an internal variable into the static allocation section.
///
/// @param[in] global_variable
/// The variable.
///
/// @return
/// True on success; false otherwise
//------------------------------------------------------------------
bool
MaterializeInternalVariable (llvm::GlobalVariable *global_variable);
//------------------------------------------------------------------
/// Handle a single externally-defined variable
///
/// @param[in] value
/// The variable.
///
/// @return
/// True on success; false otherwise
//------------------------------------------------------------------
bool
MaybeHandleVariable (llvm::Value *value);
//------------------------------------------------------------------
/// Handle a single externally-defined symbol
///
/// @param[in] symbol
/// The symbol.
///
/// @return
/// True on success; false otherwise
//------------------------------------------------------------------
bool
HandleSymbol (llvm::Value *symbol);
//------------------------------------------------------------------
/// Handle a single externally-defined Objective-C class
///
/// @param[in] classlist_reference
/// The reference, usually "01L_OBJC_CLASSLIST_REFERENCES_$_n"
/// where n (if present) is an index.
///
/// @return
/// True on success; false otherwise
//------------------------------------------------------------------
bool
HandleObjCClass(llvm::Value *classlist_reference);
//------------------------------------------------------------------
/// Handle all the arguments to a function call
///
/// @param[in] C
/// The call instruction.
///
/// @return
/// True on success; false otherwise
//------------------------------------------------------------------
bool
MaybeHandleCallArguments (llvm::CallInst *call_inst);
//------------------------------------------------------------------
/// Resolve variable references in calls to external functions
///
/// @param[in] basic_block
/// The basic block currently being processed.
///
/// @return
/// True on success; false otherwise
//------------------------------------------------------------------
bool
ResolveCalls (llvm::BasicBlock &basic_block);
//------------------------------------------------------------------
/// Remove calls to __cxa_atexit, which should never be generated by
/// expressions.
///
/// @param[in] call_inst
/// The call instruction.
///
/// @return
/// True if the scan was successful; false if some operation
/// failed
//------------------------------------------------------------------
bool
RemoveCXAAtExit (llvm::BasicBlock &basic_block);
//------------------------------------------------------------------
/// The top-level pass implementation
///
/// @param[in] basic_block
/// The function currently being processed.
///
/// @return
/// True on success; false otherwise
//------------------------------------------------------------------
bool
ResolveExternals (llvm::Function &llvm_function);
//------------------------------------------------------------------
/// A basic block-level pass to excise guard variables from the code.
/// The result for the function is passed through Clang as a static
/// variable. Static variables normally have guard variables to
/// ensure that they are only initialized once.
//------------------------------------------------------------------
//------------------------------------------------------------------
/// Rewrite a load to a guard variable to return constant 0.
///
/// @param[in] guard_load
/// The load instruction to zero out.
//------------------------------------------------------------------
void
TurnGuardLoadIntoZero(llvm::Instruction* guard_load);
//------------------------------------------------------------------
/// The top-level pass implementation
///
/// @param[in] basic_block
/// The basic block currently being processed.
///
/// @return
/// True on success; false otherwise
//------------------------------------------------------------------
bool
RemoveGuards (llvm::BasicBlock &basic_block);
//------------------------------------------------------------------
/// A module-level pass to allocate all string literals in a separate
/// allocation and redirect references to them.
//------------------------------------------------------------------
//------------------------------------------------------------------
/// The top-level pass implementation
///
/// @return
/// True on success; false otherwise
//------------------------------------------------------------------
bool
ReplaceStrings ();
//------------------------------------------------------------------
/// A basick block-level pass to find all literals that will be
/// allocated as statics by the JIT (in contrast to the Strings,
/// which already are statics) and synthesize loads for them.
//------------------------------------------------------------------
//------------------------------------------------------------------
/// The top-level pass implementation
///
/// @param[in] basic_block
/// The basic block currently being processed.
///
/// @return
/// True on success; false otherwise
//------------------------------------------------------------------
bool
ReplaceStaticLiterals (llvm::BasicBlock &basic_block);
//------------------------------------------------------------------
/// A function-level pass to make all external variable references
/// point at the correct offsets from the void* passed into the
/// function. ClangExpressionDeclMap::DoStructLayout() must be called
/// beforehand, so that the offsets are valid.
//------------------------------------------------------------------
//------------------------------------------------------------------
/// The top-level pass implementation
///
/// @param[in] llvm_function
/// The function currently being processed.
///
/// @return
/// True on success; false otherwise
//------------------------------------------------------------------
bool
ReplaceVariables (llvm::Function &llvm_function);
//------------------------------------------------------------------
/// A module-level pass to remove all global variables from the
/// module since it no longer should export or import any symbols.
//------------------------------------------------------------------
//------------------------------------------------------------------
/// The top-level pass implementation
///
/// @param[in] llvm_module
/// The module currently being processed.
///
/// @return
/// True on success; false otherwise
//------------------------------------------------------------------
bool
StripAllGVs (llvm::Module &llvm_module);
class StaticDataAllocator {
public:
StaticDataAllocator(lldb_private::IRExecutionUnit &execution_unit);
lldb_private::StreamString &GetStream()
{
return m_stream_string;
}
lldb::addr_t Allocate();
private:
lldb_private::IRExecutionUnit &m_execution_unit;
lldb_private::StreamString m_stream_string;
lldb::addr_t m_allocation;
};
/// Flags
bool m_resolve_vars; ///< True if external variable references and persistent variable references should be resolved
std::string m_func_name; ///< The name of the function to translate
lldb_private::ConstString m_result_name; ///< The name of the result variable ($0, $1, ...)
lldb_private::TypeFromParser m_result_type; ///< The type of the result variable.
llvm::Module *m_module; ///< The module being processed, or NULL if that has not been determined yet.
std::unique_ptr<llvm::DataLayout> m_target_data; ///< The target data for the module being processed, or NULL if there is no module.
lldb_private::ClangExpressionDeclMap *m_decl_map; ///< The DeclMap containing the Decls
StaticDataAllocator m_data_allocator; ///< The allocator to use for constant strings
llvm::Constant *m_CFStringCreateWithBytes; ///< The address of the function CFStringCreateWithBytes, cast to the appropriate function pointer type
llvm::Constant *m_sel_registerName; ///< The address of the function sel_registerName, cast to the appropriate function pointer type
lldb_private::Stream *m_error_stream; ///< If non-NULL, the stream on which errors should be printed
llvm::StoreInst *m_result_store; ///< If non-NULL, the store instruction that writes to the result variable. If m_has_side_effects is true, this is NULL.
bool m_result_is_pointer; ///< True if the function's result in the AST is a pointer (see comments in ASTResultSynthesizer::SynthesizeBodyResult)
llvm::GlobalVariable *m_reloc_placeholder; ///< A placeholder that will be replaced by a pointer to the final location of the static allocation.
//------------------------------------------------------------------
/// UnfoldConstant operates on a constant [Old] which has just been
/// replaced with a value [New]. We assume that new_value has
/// been properly placed early in the function, in front of the
/// first instruction in the entry basic block
/// [FirstEntryInstruction].
///
/// UnfoldConstant reads through the uses of Old and replaces Old
/// in those uses with New. Where those uses are constants, the
/// function generates new instructions to compute the result of the
/// new, non-constant expression and places them before
/// FirstEntryInstruction. These instructions replace the constant
/// uses, so UnfoldConstant calls itself recursively for those.
///
/// @param[in] llvm_function
/// The function currently being processed.
///
/// @return
/// True on success; false otherwise
//------------------------------------------------------------------
class FunctionValueCache {
public:
typedef std::function <llvm::Value *(llvm::Function *)> Maker;
FunctionValueCache (Maker const &maker);
~FunctionValueCache ();
llvm::Value *GetValue (llvm::Function *function);
private:
Maker const m_maker;
typedef std::map<llvm::Function *, llvm::Value *> FunctionValueMap;
FunctionValueMap m_values;
};
FunctionValueCache m_entry_instruction_finder;
static bool
UnfoldConstant (llvm::Constant *old_constant,
FunctionValueCache &value_maker,
FunctionValueCache &entry_instruction_finder);
//------------------------------------------------------------------
/// Construct a reference to m_reloc_placeholder with a given type
/// and offset. This typically happens after inserting data into
/// m_data_allocator.
///
/// @param[in] type
/// The type of the value being loaded.
///
/// @param[in] offset
/// The offset of the value from the base of m_data_allocator.
///
/// @return
/// The Constant for the reference, usually a ConstantExpr.
//------------------------------------------------------------------
llvm::Constant *
BuildRelocation(llvm::Type *type,
uint64_t offset);
//------------------------------------------------------------------
/// Commit the allocation in m_data_allocator and use its final
/// location to replace m_reloc_placeholder.
///
/// @param[in] module
/// The module that m_data_allocator resides in
///
/// @return
/// True on success; false otherwise
//------------------------------------------------------------------
bool
CompleteDataAllocation ();
};
#endif
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