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/*
* Copyright (C) 2009 Nicolai Haehnle.
*
* All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice (including the
* next paragraph) shall be included in all copies or substantial
* portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE COPYRIGHT OWNER(S) AND/OR ITS SUPPLIERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
*/
#include "radeon_dataflow.h"
#include "radeon_compiler.h"
#define DEALIAS_LIST_SIZE 128
struct dealias_state {
struct radeon_compiler * C;
unsigned int OldIndex:RC_REGISTER_INDEX_BITS;
unsigned int NewIndex:RC_REGISTER_INDEX_BITS;
unsigned int DealiasFail:1;
struct rc_dataflow_vector * List[DEALIAS_LIST_SIZE];
unsigned int Length;
};
static void push_dealias_vector(struct dealias_state * s, struct rc_dataflow_vector * vec)
{
if (s->Length >= DEALIAS_LIST_SIZE) {
rc_debug(s->C, "%s: list size exceeded\n", __FUNCTION__);
s->DealiasFail = 1;
return;
}
if (rc_assert(s->C, vec->File == RC_FILE_TEMPORARY && vec->Index == s->OldIndex))
return;
s->List[s->Length++] = vec;
}
static void run_dealias(struct dealias_state * s)
{
unsigned int i;
for(i = 0; i < s->Length && !s->DealiasFail; ++i) {
struct rc_dataflow_vector * vec = s->List[i];
struct rc_dataflow_ref * ref;
for(ref = vec->Refs.Next; ref != &vec->Refs; ref = ref->Next) {
if (ref->ReadInstruction->Dataflow.DstRegPrev == ref)
push_dealias_vector(s, ref->ReadInstruction->Dataflow.DstReg);
}
}
if (s->DealiasFail)
return;
for(i = 0; i < s->Length; ++i) {
struct rc_dataflow_vector * vec = s->List[i];
struct rc_dataflow_ref * ref;
vec->Index = s->NewIndex;
vec->WriteInstruction->I.DstReg.Index = s->NewIndex;
for(ref = vec->Refs.Next; ref != &vec->Refs; ref = ref->Next) {
struct rc_instruction * inst = ref->ReadInstruction;
unsigned int i;
for(i = 0; i < 3; ++i) {
if (inst->Dataflow.SrcReg[i] == ref) {
if (rc_assert(s->C, inst->I.SrcReg[i].File == RC_FILE_TEMPORARY &&
inst->I.SrcReg[i].Index == s->OldIndex))
return;
inst->I.SrcReg[i].Index = s->NewIndex;
}
}
}
}
}
/**
* Breaks register aliasing to reduce multiple assignments to a single register.
*
* This affects sequences like:
* MUL r0, ...;
* MAD r0, r1, r2, r0;
* In this example, a new register will be used for the destination of the
* second MAD.
*
* The purpose of this dealiasing is to make the resulting code more SSA-like
* and therefore make it easier to move instructions around.
* This is of crucial importance for R300 fragment programs, where de-aliasing
* can help to reduce texture indirections, but other targets can benefit from
* it as well.
*
* \note When compiling GLSL, there may be some benefit gained from breaking
* up vectors whose components are unrelated. This is not done yet and should
* be investigated at some point (of course, a matching pass to re-merge
* components would be required).
*/
void rc_dataflow_dealias(struct radeon_compiler * c)
{
struct dealias_state s;
memset(&s, 0, sizeof(s));
s.C = c;
struct rc_instruction * inst;
for(inst = c->Program.Instructions.Prev; inst != &c->Program.Instructions; inst = inst->Prev) {
if (!inst->Dataflow.DstRegAliased || inst->Dataflow.DstReg->File != RC_FILE_TEMPORARY)
continue;
if (inst->Dataflow.DstReg->UseMask & ~inst->I.DstReg.WriteMask)
continue;
s.OldIndex = inst->I.DstReg.Index;
s.NewIndex = rc_find_free_temporary(c);
s.DealiasFail = 0;
s.Length = 0;
inst->Dataflow.DstRegAliased = 0;
if (inst->Dataflow.DstRegPrev) {
rc_dataflow_remove_ref(inst->Dataflow.DstRegPrev);
inst->Dataflow.DstRegPrev = 0;
}
push_dealias_vector(&s, inst->Dataflow.DstReg);
run_dealias(&s);
}
}
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