demotool/c-opopt.hh

#pragma once
#include "c-opast.hh"
#include "c-opcomp.hh"

#include <ebcl/Algorithms.hh>

struct T_SyncCurves;

namespace opopt {

// Persistent data for the various stages of the optimizer.
struct T_OptData
{
	// Logger
	F_OPLogger logger{ []( auto , auto ) {} };

	// List of errors generated by the optimizer
	T_Array< ebcl::T_SRDError > errors;

	// If the size of the ouput is fixed, this field contains it as a
	// <width,height> pair.
	T_Optional< std::pair< uint32_t , uint32_t > > fixedSize;

	// The curves that will be bound to the inputs.
	T_SyncCurves const* curves{ nullptr };

	// A visitor to be used for the tree
	ebcl::T_Visitor< opast::A_Node > visitor{ opast::ASTVisitorBrowser };

	//----------------------------------------------------------------------

	// Table of input declarations; used to fold constant inputs.
	struct T_InputDecl {
		ebcl::T_SRDLocation location;
		float value;
	};
	T_Optional< T_KeyValueTable< T_String , T_Array< T_InputDecl > > > inputDecls;

	void findInputDecls( T_OpsParserOutput& program ) noexcept;

	//----------------------------------------------------------------------

	// Data for instruction numbering
	struct T_InstrPos {
		uint32_t index;
		opast::A_InstructionNode* node;
		bool lastOfSequence;
		uint32_t funcIndex;
	};
	T_HashIndex instrIndex;
	T_Array< T_InstrPos > instructions;

	void numberInstructions( T_OpsParserOutput& program ) noexcept;
	uint32_t indexOf( opast::A_InstructionNode const& instr ) noexcept;

	//----------------------------------------------------------------------

	// Basic block of consecutive instructions
	struct T_BasicBlock
	{
		uint32_t first;
		uint32_t count;

		explicit T_BasicBlock( uint32_t first ) noexcept
			: first( first ) , count( 1 )
		{ }
	};

	// Control flow graph node
	struct T_CtrlFlowNode
	{
		T_Optional< T_BasicBlock > instructions;
		T_AutoArray< uint32_t , 16 > inbound;
		T_AutoArray< uint32_t , 16 > outbound;
	};
	using P_CtrlFlowNode = T_OwnPtr< T_CtrlFlowNode >;

	// Special nodes in the graph
	static constexpr uint32_t CFG_ENTER = 0;
	static constexpr uint32_t CFG_MAINLOOP = 1;
	static constexpr uint32_t CFG_END = 2;

	// Control flow graph
	T_Array< P_CtrlFlowNode > ctrlFlowGraph;
	T_KeyValueTable< T_String , T_BasicBlock > cfgFunctions;

	// Build the control flow graph. Instruction numbering must be
	// up-to-date before calling this.
	void buildControlFlowGraph(
			T_OpsParserOutput& program ) noexcept;

	//----------------------------------------------------------------------

	// Type of variables used for use/define chains
	enum class E_UDVarType {
		GLOBAL ,
		LOCAL ,
		ARGUMENT
	};

	// Variable identifier for the U/D chains
	struct T_VarId
	{
		E_UDVarType type;			// Var type
		T_String name;				// Var name
		T_String owner;				// Function name (empty for globals)

		explicit T_VarId( T_String const& name ) noexcept
			: type{ E_UDVarType::GLOBAL } , name{ name } ,
				owner{ }
		{ }

		T_VarId( T_String const& name ,
				T_String const& owner ,
				const bool isArgument ) noexcept
			: type{ isArgument ? E_UDVarType::ARGUMENT : E_UDVarType::LOCAL } ,
				name{ name } , owner{ owner }
		{ assert( owner ); }

		bool operator ==( T_VarId const& other ) const noexcept
		{
			return type == other.type && name == other.name
				&& owner == other.owner;
		}

		bool operator !=( T_VarId const& other ) const noexcept
		{
			return type != other.type || name != other.name
				|| owner != other.owner;
		}
	};

	// Use/define chain data
	struct T_VarUDRecord
	{
		uint32_t node;				// Instruction that uses or sets it
		uint32_t fnIndex;			// Function in which the use/define is located
		T_AutoArray< uint32_t , 16 > refs;	// Corresponding uses/defines
	};

	// Use/define chains for a variable
	struct T_VarUseDefine
	{
		T_VarId var;
		T_AutoArray< T_VarUDRecord , 16 > uses;
		T_AutoArray< T_VarUDRecord , 4> defines;

		explicit T_VarUseDefine( T_VarId const& id )
			: var{ id }
		{ }
	};

	// Use/define chains
	T_ObjectTable< T_VarId , T_VarUseDefine > varUDChains{
		[]( auto const& var ) -> T_VarId {
			return var.var;
		} };

	// Build the use/define chains. The control flow graph must be up to
	// date before calling this.
	void buildUseDefineChains(
			T_OpsParserOutput& program ) noexcept;
};

uint32_t ComputeHash( T_OptData::T_VarId const& id ) noexcept;


/*= INDIVIDUAL OPTIMISATIONS =================================================*/
// All functions below return true if transformations were made, false if not.

// Attempts to fold constant expressions into single constants.
//
bool FoldConstants(
		T_OpsParserOutput& program ,
		T_OptData& optData ) noexcept;

// Attempts to propagate values from variables that contain constants to the
// locations at which they are used.
//
bool PropagateConstants(
		T_OpsParserOutput& program ,
		T_OptData& optData ) noexcept;

// Attempt to remove blocks of code that will not be executed because of
// constant conditions.
//
bool RemoveDeadCode(
		T_OpsParserOutput& program ,
		T_OptData& optData ) noexcept;


} // namespace opopt