Lowering

Lowering is the process of transforming a highlevel representation (a representation closer to the sourcecode) into a lower-level representation (something closer to the target machine). More...

Data Structures
struct	i_call_record
	An intrinsic call record. More...
struct	i_instr_record
	An intrinsic instruction record. More...
union	i_record
	An intrinsic record. More...
struct	runtime_rt
	A runtime routine description. More...
Typedefs
typedef int	lower_mux_callback (ir_node *mux)
	Used as callback, whenever a lowerable mux is found.
typedef int(*	i_mapper_func )(ir_node *node, void *ctx)
	An intrinsic mapper function.
Enumerations
enum	ikind { INTRINSIC_CALL = 0, INTRINSIC_INSTR }
	kind of an instruction record More...
Functions
void	lower_CopyB (ir_graph *irg, unsigned max_small_size, unsigned min_large_size, int allow_misalignments)
	Lower small CopyB nodes to Load/Store nodes, preserve medium-sized CopyB nodes and replace large CopyBs by a call to memcpy, depending on the given parameters.
void	lower_switch (ir_graph *irg, unsigned small_switch, unsigned spare_size, int allow_out_of_bounds)
	Lowers all Switches (Cond nodes with non-boolean mode) depending on spare_size.
void	lower_highlevel_graph (ir_graph *irg)
	Replaces SymConsts by a real constant if possible.
ir_graph_pass_t *	lower_highlevel_graph_pass (const char *name)
	Creates an ir_graph pass for lower_highlevel_graph().
void	lower_highlevel (void)
	Replaces SymConsts by a real constant if possible.
void	lower_const_code (void)
	does the same as lower_highlevel for all nodes on the const code irg
ir_prog_pass_t *	lower_const_code_pass (const char *name)
	Creates an ir_prog pass for lower_const_code().
void	lower_mux (ir_graph *irg, lower_mux_callback *cb_func)
	Lowers all mux nodes in the given graph.
ir_graph_pass_t *	lower_mux_pass (const char *name, lower_mux_callback *cb_func)
	Creates an ir_graph pass for lower_mux().
size_t	lower_intrinsics (i_record *list, size_t length, int part_block_used)
	Go through all graphs and map calls to intrinsic functions and instructions.
ir_prog_pass_t *	lower_intrinsics_pass (const char *name, i_record *list, size_t length, int part_block_used)
	Creates an irprog pass for lower_intrinsics.
int	i_mapper_abs (ir_node *call, void *ctx)
	A mapper for the integer/float absolute value: type abs(type v).
int	i_mapper_bswap (ir_node *call, void *ctx)
	A mapper for the integer byte swap value: type bswap(type v).
int	i_mapper_sqrt (ir_node *call, void *ctx)
	A mapper for the floating point sqrt(v): floattype sqrt(floattype v);.
int	i_mapper_cbrt (ir_node *call, void *ctx)
	A mapper for the floating point cbrt(v): floattype sqrt(floattype v);.
int	i_mapper_pow (ir_node *call, void *ctx)
	A mapper for the floating point pow(a, b): floattype pow(floattype a, floattype b);.
int	i_mapper_exp (ir_node *call, void *ctx)
	A mapper for the floating point exp(a): floattype exp(floattype a);.
int	i_mapper_exp2 (ir_node *call, void *ctx)
	A mapper for the floating point exp2(a): floattype exp2(floattype a);.
int	i_mapper_exp10 (ir_node *call, void *ctx)
	A mapper for the floating point exp10(a): floattype exp10(floattype a);.
int	i_mapper_log (ir_node *call, void *ctx)
	A mapper for the floating point log(a): floattype log(floattype a);.
int	i_mapper_log2 (ir_node *call, void *ctx)
	A mapper for the floating point log(a): floattype log(floattype a);.
int	i_mapper_log10 (ir_node *call, void *ctx)
	A mapper for the floating point log(a): floattype log(floattype a);.
int	i_mapper_sin (ir_node *call, void *ctx)
	A mapper for the floating point sin(a): floattype sin(floattype a);.
int	i_mapper_cos (ir_node *call, void *ctx)
	A mapper for the floating point sin(a): floattype cos(floattype a);.
int	i_mapper_tan (ir_node *call, void *ctx)
	A mapper for the floating point tan(a): floattype tan(floattype a);.
int	i_mapper_asin (ir_node *call, void *ctx)
	A mapper for the floating point asin(a): floattype asin(floattype a);.
int	i_mapper_acos (ir_node *call, void *ctx)
	A mapper for the floating point acos(a): floattype acos(floattype a);.
int	i_mapper_atan (ir_node *call, void *ctx)
	A mapper for the floating point atan(a): floattype atan(floattype a);.
int	i_mapper_sinh (ir_node *call, void *ctx)
	A mapper for the floating point sinh(a): floattype sinh(floattype a);.
int	i_mapper_cosh (ir_node *call, void *ctx)
	A mapper for the floating point cosh(a): floattype cosh(floattype a);.
int	i_mapper_tanh (ir_node *call, void *ctx)
	A mapper for the floating point tanh(a): floattype tanh(floattype a);.
int	i_mapper_strcmp (ir_node *call, void *ctx)
	A mapper for the strcmp-Function: inttype strcmp(char pointer a, char pointer b);.
int	i_mapper_strncmp (ir_node *call, void *ctx)
	A mapper for the strncmp-Function: inttype strncmp(char pointer a, char pointer b, inttype len);.
int	i_mapper_strcpy (ir_node *call, void *ctx)
	A mapper for the strcpy-Function: char pointer strcpy(char pointer a, char pointer b);.
int	i_mapper_strlen (ir_node *call, void *ctx)
	A mapper for the strlen-Function: inttype strlen(char pointer a);.
int	i_mapper_memcpy (ir_node *call, void *ctx)
	A mapper for the memcpy-Function: void pointer memcpy(void pointer d, void pointer s, inttype c);.
int	i_mapper_mempcpy (ir_node *call, void *ctx)
	A mapper for the mempcpy-Function: void pointer mempcpy(void pointer d, void pointer s, inttype c);.
int	i_mapper_memmove (ir_node *call, void *ctx)
	A mapper for the memmove-Function: void pointer memmove(void pointer d, void pointer s, inttype c);.
int	i_mapper_memset (ir_node *call, void *ctx)
	A mapper for the memset-Function: void pointer memset(void pointer d, inttype C, inttype len);.
int	i_mapper_memcmp (ir_node *call, void *ctx)
	A mapper for the strncmp-Function: inttype memcmp(void pointer a, void pointer b, inttype len);.
int	i_mapper_alloca (ir_node *call, void *ctx)
	A mapper for the alloca() function: pointer alloca(inttype size) Replaces the call by a Alloca(stack_alloc) node.
int	i_mapper_RuntimeCall (ir_node *node, runtime_rt *rt)
	A mapper for mapping unsupported instructions to runtime calls.

---

Detailed Description

Lowering is the process of transforming a highlevel representation (a representation closer to the sourcecode) into a lower-level representation (something closer to the target machine).

---

Typedef Documentation

typedef int(* i_mapper_func)(ir_node *node, void *ctx)

An intrinsic mapper function.

Parameters:

node	the IR-node that will be mapped
ctx	a context

Returns:

non-zero if the call was mapped

Definition at line 166 of file lowering.h.

typedef int lower_mux_callback(ir_node *mux)

Used as callback, whenever a lowerable mux is found.

The return value indicates, whether the mux should be lowered. This may be used, to lower floating point muxes, while keeping mux nodes for integers, for example.

Parameters:

mux	The mux node that may be lowered.

Returns:

A non-zero value indicates that the mux should be lowered.

Definition at line 134 of file lowering.h.

---

Enumeration Type Documentation

enum ikind

kind of an instruction record

See also:

i_record

Enumerator:

INTRINSIC_CALL	the record represents an intrinsic call
INTRINSIC_INSTR	the record represents an intrinsic instruction

Definition at line 170 of file lowering.h.

---

Function Documentation

int i_mapper_abs	(	ir_node *	call,
		void *	ctx
	)

A mapper for the integer/float absolute value: type abs(type v).

Replaces the call by a Abs node.

Returns:

always 1

int i_mapper_acos	(	ir_node *	call,
		void *	ctx
	)

A mapper for the floating point acos(a): floattype acos(floattype a);.

Returns:

1 if the tan call was removed, 0 else.

int i_mapper_alloca	(	ir_node *	call,
		void *	ctx
	)

A mapper for the alloca() function: pointer alloca(inttype size) Replaces the call by a Alloca(stack_alloc) node.

Returns:

always 1

int i_mapper_asin	(	ir_node *	call,
		void *	ctx
	)

A mapper for the floating point asin(a): floattype asin(floattype a);.

Returns:

1 if the asin call was removed, 0 else.

int i_mapper_atan	(	ir_node *	call,
		void *	ctx
	)

A mapper for the floating point atan(a): floattype atan(floattype a);.

Returns:

1 if the atan call was removed, 0 else.

int i_mapper_bswap	(	ir_node *	call,
		void *	ctx
	)

A mapper for the integer byte swap value: type bswap(type v).

Replaces the call by a builtin[ir_bk_bswap] node.

Returns:

always 1

int i_mapper_cbrt	(	ir_node *	call,
		void *	ctx
	)

A mapper for the floating point cbrt(v): floattype sqrt(floattype v);.

Returns:

1 if the cbrt call was removed, 0 else.

int i_mapper_cos	(	ir_node *	call,
		void *	ctx
	)

A mapper for the floating point sin(a): floattype cos(floattype a);.

Returns:

1 if the cos call was removed, 0 else.

int i_mapper_cosh	(	ir_node *	call,
		void *	ctx
	)

A mapper for the floating point cosh(a): floattype cosh(floattype a);.

Returns:

1 if the cosh call was removed, 0 else.

int i_mapper_exp	(	ir_node *	call,
		void *	ctx
	)

A mapper for the floating point exp(a): floattype exp(floattype a);.

Returns:

1 if the exp call was removed, 0 else.

int i_mapper_exp10	(	ir_node *	call,
		void *	ctx
	)

A mapper for the floating point exp10(a): floattype exp10(floattype a);.

Returns:

1 if the exp call was removed, 0 else.

int i_mapper_exp2	(	ir_node *	call,
		void *	ctx
	)

A mapper for the floating point exp2(a): floattype exp2(floattype a);.

Returns:

1 if the exp call was removed, 0 else.

int i_mapper_log	(	ir_node *	call,
		void *	ctx
	)

A mapper for the floating point log(a): floattype log(floattype a);.

Returns:

1 if the log call was removed, 0 else.

int i_mapper_log10	(	ir_node *	call,
		void *	ctx
	)

A mapper for the floating point log(a): floattype log(floattype a);.

Returns:

1 if the log call was removed, 0 else.

int i_mapper_log2	(	ir_node *	call,
		void *	ctx
	)

A mapper for the floating point log(a): floattype log(floattype a);.

Returns:

1 if the log call was removed, 0 else.

int i_mapper_memcmp	(	ir_node *	call,
		void *	ctx
	)

A mapper for the strncmp-Function: inttype memcmp(void pointer a, void pointer b, inttype len);.

Returns:

1 if the strncmp call was removed, 0 else.

int i_mapper_memcpy	(	ir_node *	call,
		void *	ctx
	)

A mapper for the memcpy-Function: void pointer memcpy(void pointer d, void pointer s, inttype c);.

Returns:

1 if the memcpy call was removed, 0 else.

int i_mapper_memmove	(	ir_node *	call,
		void *	ctx
	)

A mapper for the memmove-Function: void pointer memmove(void pointer d, void pointer s, inttype c);.

Returns:

1 if the memmove call was removed, 0 else.

int i_mapper_mempcpy	(	ir_node *	call,
		void *	ctx
	)

A mapper for the mempcpy-Function: void pointer mempcpy(void pointer d, void pointer s, inttype c);.

Returns:

1 if the mempcpy call was removed, 0 else.

int i_mapper_memset	(	ir_node *	call,
		void *	ctx
	)

A mapper for the memset-Function: void pointer memset(void pointer d, inttype C, inttype len);.

Returns:

1 if the memset call was removed, 0 else.

int i_mapper_pow	(	ir_node *	call,
		void *	ctx
	)

A mapper for the floating point pow(a, b): floattype pow(floattype a, floattype b);.

Returns:

1 if the pow call was removed, 0 else.

int i_mapper_RuntimeCall	(	ir_node *	node,
		runtime_rt *	rt
	)

A mapper for mapping unsupported instructions to runtime calls.

Maps a op(arg_0, ..., arg_n) into a call to a runtime function rt(arg_0, ..., arg_n).

The mapping is only done, if the modes of all arguments matches the modes of rt's argument. Further, if op has a memory input, the generated Call uses it, else it gets a NoMem. The pinned state of the Call will be set to the pinned state of op.

Note that i_mapper_RuntimeCall() must be used with a i_instr_record.

Returns:

1 if an op was mapped, 0 else

Some examples:

• Maps signed Div nodes to calls to rt_Div():

    runtime_rt rt_Div = {
      ent("int rt_Div(int, int)"),
      mode_T,
      mode_Is,
      pn_Div_M,
      pn_Div_X_regular,
      pn_Div_X_except,
      pn_Div_M,
      pn_Div_res
    };
    i_instr_record map_Div = {
      INTRINSIC_INSTR,
      op_Div,
      i_mapper_RuntimeCall,
      &rt_Div,
      NULL
    };
  

• Maps ConvD(F) to calls to rt_Float2Div():

    runtime_rt rt_Float2Double = {
      ent("double rt_Float2Div(float)"),
      get_type_mode("double"),
      NULL,
      -1,
      -1,
      -1,
      -1,
      -1
    };
    i_instr_record map_Float2Double = {
      INTRINSIC_INSTR,
      op_Conv,
      i_mapper_RuntimeCall,
      &rt_Float2Double,
      NULL
    };
  

int i_mapper_sin	(	ir_node *	call,
		void *	ctx
	)

A mapper for the floating point sin(a): floattype sin(floattype a);.

Returns:

1 if the sin call was removed, 0 else.

int i_mapper_sinh	(	ir_node *	call,
		void *	ctx
	)

A mapper for the floating point sinh(a): floattype sinh(floattype a);.

Returns:

1 if the sinh call was removed, 0 else.

int i_mapper_sqrt	(	ir_node *	call,
		void *	ctx
	)

A mapper for the floating point sqrt(v): floattype sqrt(floattype v);.

Returns:

1 if the sqrt call was removed, 0 else.

int i_mapper_strcmp	(	ir_node *	call,
		void *	ctx
	)

A mapper for the strcmp-Function: inttype strcmp(char pointer a, char pointer b);.

Returns:

1 if the strcmp call was removed, 0 else.

int i_mapper_strcpy	(	ir_node *	call,
		void *	ctx
	)

A mapper for the strcpy-Function: char pointer strcpy(char pointer a, char pointer b);.

Returns:

1 if the strcpy call was removed, 0 else.

int i_mapper_strlen	(	ir_node *	call,
		void *	ctx
	)

A mapper for the strlen-Function: inttype strlen(char pointer a);.

Returns:

1 if the strlen call was removed, 0 else.

int i_mapper_strncmp	(	ir_node *	call,
		void *	ctx
	)

A mapper for the strncmp-Function: inttype strncmp(char pointer a, char pointer b, inttype len);.

Returns:

1 if the strncmp call was removed, 0 else.

int i_mapper_tan	(	ir_node *	call,
		void *	ctx
	)

A mapper for the floating point tan(a): floattype tan(floattype a);.

Returns:

1 if the tan call was removed, 0 else.

int i_mapper_tanh	(	ir_node *	call,
		void *	ctx
	)

A mapper for the floating point tanh(a): floattype tanh(floattype a);.

Returns:

1 if the tanh call was removed, 0 else.

void lower_const_code

(

void

)

does the same as lower_highlevel for all nodes on the const code irg

ir_prog_pass_t* lower_const_code_pass

(

const char *

name

)

Creates an ir_prog pass for lower_const_code().

Parameters:

name	the name of this pass or NULL

Returns:

the newly created ir_prog pass

void lower_CopyB	(	ir_graph *	irg,
		unsigned	max_small_size,
		unsigned	min_large_size,
		int	allow_misalignments
	)

Lower small CopyB nodes to Load/Store nodes, preserve medium-sized CopyB nodes and replace large CopyBs by a call to memcpy, depending on the given parameters.

Small CopyB nodes (size <= max_small_size) are turned into a series of loads and stores. Medium-sized CopyB nodes (max_small_size < size < min_large_size) are left untouched. Large CopyB nodes (size >= min_large_size) are turned into a memcpy call.

Parameters:

irg	The graph to be lowered.
max_small_size	The maximum number of bytes for a CopyB node so that it is still considered 'small'.
min_large_size	The minimum number of bytes for a CopyB node so that it is regarded as 'large'.
allow_misalignments	Backend can handle misaligned loads and stores.

void lower_highlevel

(

void

)

Replaces SymConsts by a real constant if possible.

Replaces Sel nodes by address computation. Also resolves array access. Handle bit fields by added And/Or calculations. Lowers all graphs.

Note:

There is NO lowering of objects oriented types. This is highly compiler and ABI specific and should be placed directly in the compiler.

void lower_highlevel_graph

(

ir_graph *

irg

)

Replaces SymConsts by a real constant if possible.

Replaces Sel nodes by address computation. Also resolves array access. Handle bit fields by added And/Or calculations.

Parameters:

irg	the graph to lower

Note:

: There is NO lowering ob objects oriented types. This is highly compiler and ABI specific and should be placed directly in the compiler.

ir_graph_pass_t* lower_highlevel_graph_pass

(

const char *

name

)

Creates an ir_graph pass for lower_highlevel_graph().

Parameters:

name	the name of this pass or NULL

Returns:

the newly created ir_graph pass

size_t lower_intrinsics	(	i_record *	list,
		size_t	length,
		int	part_block_used
	)

Go through all graphs and map calls to intrinsic functions and instructions.

Every call or instruction is reported to its mapper function, which is responsible for rebuilding the graph.

current_ir_graph is always set.

Parameters:

list	an array of intrinsic map records
length	the length of the array
part_block_used	set to true if part_block() must be using during lowering

Returns:

number of found intrinsics.

ir_prog_pass_t* lower_intrinsics_pass	(	const char *	name,
		i_record *	list,
		size_t	length,
		int	part_block_used
	)

Creates an irprog pass for lower_intrinsics.

Parameters:

name	the name of this pass or NULL
list	an array of intrinsic map records
length	the length of the array
part_block_used	set to true if part_block() must be using during lowering

void lower_mux	(	ir_graph *	irg,
		lower_mux_callback *	cb_func
	)

Lowers all mux nodes in the given graph.

A callback function may be given, to select the mux nodes to lower.

Parameters:

irg	The graph to lower mux nodes in.
cb_func	The callback function for mux selection. Can be NULL, to lower all mux nodes.

ir_graph_pass_t* lower_mux_pass	(	const char *	name,
		lower_mux_callback *	cb_func
	)

Creates an ir_graph pass for lower_mux().

Parameters:

name	the name of this pass or NULL
cb_func	The callback function for mux selection. Can be NULL, to lower all mux nodes.

Returns:

the newly created ir_graph pass

void lower_switch	(	ir_graph *	irg,
		unsigned	small_switch,
		unsigned	spare_size,
		int	allow_out_of_bounds
	)

Lowers all Switches (Cond nodes with non-boolean mode) depending on spare_size.

They will either remain the same or be converted into if-cascades.

Parameters:

irg	The ir graph to be lowered.
small_switch	If switch has <= cases then change it to an if-cascade.
spare_size	Allowed spare size for table switches in machine words. (Default in edgfe: 128)
allow_out_of_bounds	backend can handle out-of-bounds values (values bigger than minimum and maximum proj number)