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r300/compiler: Unroll loops that decrement the counter.

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e.g. for(i=10; i>0; i--)
This commit is contained in:
Tom Stellard 2010-06-05 12:59:02 -07:00 • committed by Marek Olšák
parent 0f1109ce36
commit 6f1b6814bc
1 changed files with 87 additions and 53 deletions
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140
src/mesa/drivers/dri/r300/compiler/radeon_emulate_loops.c
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@ -34,6 +34,10 @@
#include "radeon_compiler.h"
#include "radeon_dataflow.h"
#define VERBOSE 0
#define DBG(...) do { if (VERBOSE) fprintf(stderr, __VA_ARGS__); } while(0)
struct emulate_loop_state {
struct radeon_compiler * C;
struct loop_info * Loops;
@ -150,39 +154,54 @@ static void get_incr_amount(void * data, struct rc_instruction * inst,
rc_register_file file, unsigned int index, unsigned int mask)
{
struct count_inst * count_inst = data;
int amnt_src_index;
struct rc_opcode_info * opcode;
float amount;
if(file != RC_FILE_TEMPORARY ||
count_inst->Index != index ||
(1 << GET_SWZ(count_inst->Swz,0) != mask)){
return;
}
switch(inst->U.I.Opcode){
int incr_reg;
case RC_OPCODE_ADD:
{
if(inst->U.I.SrcReg[0].File == RC_FILE_TEMPORARY &&
inst->U.I.SrcReg[0].Index == count_inst->Index &&
inst->U.I.SrcReg[0].Swizzle == count_inst->Swz){
incr_reg = 1;
} else if( inst->U.I.SrcReg[1].File == RC_FILE_TEMPORARY &&
inst->U.I.SrcReg[1].Index == count_inst->Index &&
inst->U.I.SrcReg[1].Swizzle == count_inst->Swz){
incr_reg = 0;
}
else{
count_inst->Unknown = 1;
return;
}
if(src_reg_is_immediate(&inst->U.I.SrcReg[incr_reg],
count_inst->C)){
count_inst->Amount = get_constant_value(count_inst->C,
&inst->U.I.SrcReg[incr_reg], 0);
}
else{
count_inst->Unknown = 1 ;
return;
}
break;
/* Find the index of the counter register. */
opcode = rc_get_opcode_info(inst->U.I.Opcode);
if(opcode->NumSrcRegs != 2){
count_inst->Unknown = 1;
return;
}
if(inst->U.I.SrcReg[0].File == RC_FILE_TEMPORARY &&
inst->U.I.SrcReg[0].Index == count_inst->Index &&
inst->U.I.SrcReg[0].Swizzle == count_inst->Swz){
amnt_src_index = 1;
} else if( inst->U.I.SrcReg[1].File == RC_FILE_TEMPORARY &&
inst->U.I.SrcReg[1].Index == count_inst->Index &&
inst->U.I.SrcReg[1].Swizzle == count_inst->Swz){
amnt_src_index = 0;
}
else{
count_inst->Unknown = 1;
return;
}
if(src_reg_is_immediate(&inst->U.I.SrcReg[amnt_src_index],
count_inst->C)){
amount = get_constant_value(count_inst->C,
&inst->U.I.SrcReg[amnt_src_index], 0);
}
else{
count_inst->Unknown = 1 ;
return;
}
switch(inst->U.I.Opcode){
case RC_OPCODE_ADD:
count_inst->Amount += amount;
break;
case RC_OPCODE_SUB:
if(amnt_src_index == 0){
count_inst->Unknown = 0;
return;
}
count_inst->Amount -= amount;
break;
default:
count_inst->Unknown = 1;
return;
@ -192,7 +211,7 @@ static void get_incr_amount(void * data, struct rc_instruction * inst,
static int transform_const_loop(struct emulate_loop_state * s,
struct loop_info * loop,
struct rc_instruction * slt)
struct rc_instruction * cond)
{
int end_loops = 1;
int iterations;
@ -205,17 +224,16 @@ static int transform_const_loop(struct emulate_loop_state * s,
/* Find the counter and the upper limit */
/* limit < counter */
if(src_reg_is_immediate(&slt->U.I.SrcReg[0], s->C)){
limit = &slt->U.I.SrcReg[0];
counter = &slt->U.I.SrcReg[1];
if(src_reg_is_immediate(&cond->U.I.SrcReg[0], s->C)){
limit = &cond->U.I.SrcReg[0];
counter = &cond->U.I.SrcReg[1];
}
/* counter < limit */
else if(src_reg_is_immediate(&slt->U.I.SrcReg[1], s->C)){
limit = &slt->U.I.SrcReg[1];
counter = &slt->U.I.SrcReg[0];
else if(src_reg_is_immediate(&cond->U.I.SrcReg[1], s->C)){
limit = &cond->U.I.SrcReg[1];
counter = &cond->U.I.SrcReg[0];
}
else{
DBG("No constant limit.\n");
return 0;
}
@ -229,9 +247,10 @@ static int transform_const_loop(struct emulate_loop_state * s,
rc_for_all_writes_mask(inst, update_const_value, &counter_value);
}
if(!counter_value.HasValue){
DBG("Initial counter value cannot be determined.\n");
return 0;
}
DBG("Initial counter value is %f\n", counter_value.Value);
/* Determine how the counter is modified each loop */
count_inst.C = s->C;
count_inst.Index = counter->Index;
@ -249,6 +268,10 @@ static int transform_const_loop(struct emulate_loop_state * s,
loop->EndLoop = inst;
end_loops--;
break;
/* XXX Check if the counter is modified within an if statement.
*/
case RC_OPCODE_IF:
break;
default:
rc_for_all_writes_mask(inst, get_incr_amount, &count_inst);
if(count_inst.Unknown){
@ -257,23 +280,27 @@ static int transform_const_loop(struct emulate_loop_state * s,
break;
}
}
/* Infinite loop */
if(count_inst.Amount == 0.0f){
return 0;
}
/* Calculate the number of iterations of this loop */
DBG("Counter is increased by %f each iteration.\n", count_inst.Amount);
/* Calculate the number of iterations of this loop. Keeping this
* simple, since we only support increment and decrement loops.
*/
limit_value = get_constant_value(s->C, limit, 0);
iterations = (int) ((limit_value - counter_value.Value) /
count_inst.Amount);
DBG("Loop will have %d iterations.\n", iterations);
/* Prepare loop for unrolling */
/* Remove the first 4 instructions inside the loop, which are part
* of the conditional and no longer needed(SGE, IF, BRK, ENDIF).
* of the conditional and no longer needed.
*/
rc_remove_instruction(loop->BeginLoop->Next);
rc_remove_instruction(loop->BeginLoop->Next);
rc_remove_instruction(loop->BeginLoop->Next);
rc_remove_instruction(loop->BeginLoop->Next);
rc_remove_instruction(loop->BeginLoop->Next); /* SLT/SGE */
rc_remove_instruction(loop->BeginLoop->Next); /* IF */
rc_remove_instruction(loop->BeginLoop->Next); /* BRK */
rc_remove_instruction(loop->BeginLoop->Next); /* ENDIF */
loop_unroll(s, loop, iterations);
loop->EndLoop = NULL;
@ -283,13 +310,13 @@ static int transform_const_loop(struct emulate_loop_state * s,
/**
* This function prepares a loop to be unrolled by converting it into an if
* statement. Here is an outline of the conversion process:
* BGNLOOP; -> BGNLOOP;
* SGE temp[0], temp[1], temp[2]; -> SLT temp[0], temp[1], temp[2];
* IF temp[0]; -> IF temp[0];
* BRK; ->
* ENDIF; -> <Loop Body>
* <Loop Body> -> ENDIF;
* ENDLOOP; -> ENDLOOP
* BGNLOOP; -> BGNLOOP;
* SGE/SLT temp[0], temp[1], temp[2]; -> SLT/SGE temp[0], temp[1], temp[2];
* IF temp[0]; -> IF temp[0];
* BRK; ->
* ENDIF; -> <Loop Body>
* <Loop Body> -> ENDIF;
* ENDLOOP; -> ENDLOOP
*
* @param inst A pointer to a BGNLOOP instruction.
* @return A pointer to the ENDLOOP instruction.
@ -307,9 +334,16 @@ static struct rc_instruction * transform_loop(struct emulate_loop_state * s,
memset(loop, 0, sizeof(struct loop_info));
loop->BeginLoop = inst;
/* Reverse the SGE instruction */
/* Reverse the conditional instruction */
ptr = inst->Next;
ptr->U.I.Opcode = RC_OPCODE_SLT;
switch(ptr->U.I.Opcode){
case RC_OPCODE_SGE:
ptr->U.I.Opcode = RC_OPCODE_SLT;
break;
case RC_OPCODE_SLT:
ptr->U.I.Opcode = RC_OPCODE_SGE;
break;
}
/* Check if the number of loops is known at compile time. */
if(transform_const_loop(s, loop, ptr)){