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r300: merge simple movs with constant swizzles together

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This pass will merge instructions like these

MOV output[0].x, temp[5].x___;
MOV output[0].yzw, none._001;

into

MOV output[0].xyzw, temp[5].x001;

It is currently very careful with control flow and dependency
tracking, so there is still room for improvements.

Shader-db stats with RV530:
total instructions in shared programs: 132486 -> 132256 (-0.17%)
instructions in affected programs: 6186 -> 5956 (-3.72%)
helped: 65
HURT: 0
total temps in shared programs: 18035 -> 18014 (-0.12%)
temps in affected programs: 295 -> 274 (-7.12%)
helped: 22
HURT: 1

Signed-off-by: Pavel Ondračka <pavel.ondracka@gmail.com>
Reviewed-by: Filip Gawin <filip@gawin.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16657>
This commit is contained in:
Pavel Ondračka 2022-05-20 11:11:07 +02:00 • committed by Marge Bot
parent 0fcd423a6a
commit 6c2959c025
1 changed files with 82 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

82
src/gallium/drivers/r300/compiler/radeon_optimize.c
View file

@ -887,6 +887,86 @@ static int peephole(struct radeon_compiler * c, struct rc_instruction * inst)
return 0;
}
static unsigned int merge_swizzles(unsigned int swz1, unsigned int swz2) {
unsigned int new_swz = rc_init_swizzle(RC_SWIZZLE_UNUSED, 0);
for (unsigned int chan = 0; chan < 4; chan++) {
unsigned int swz = GET_SWZ(swz1, chan);
if (swz != RC_SWIZZLE_UNUSED) {
SET_SWZ(new_swz, chan, swz);
continue;
}
swz = GET_SWZ(swz2, chan);
SET_SWZ(new_swz, chan, swz);
}
return new_swz;
}
static int merge_movs(struct radeon_compiler * c, struct rc_instruction * inst)
{
unsigned int orig_dst_reg = inst->U.I.DstReg.Index;
unsigned int orig_dst_file = inst->U.I.DstReg.File;
unsigned int orig_dst_wmask = inst->U.I.DstReg.WriteMask;
unsigned int orig_src_reg = inst->U.I.SrcReg[0].Index;
unsigned int orig_src_file = inst->U.I.SrcReg[0].File;
struct rc_instruction * cur = inst;
while (cur!= &c->Program.Instructions) {
cur = cur->Next;
const struct rc_opcode_info * opcode = rc_get_opcode_info(cur->U.I.Opcode);
/* Keep it simple for now and stop when encountering any
* control flow.
*/
if (opcode->IsFlowControl)
return 0;
/* Stop when the original destination is overwritten */
if (orig_dst_reg == cur->U.I.DstReg.Index &&
orig_dst_file == cur->U.I.DstReg.File &&
(orig_dst_wmask & cur->U.I.DstReg.WriteMask) != 0)
return 0;
/* Stop the search when the original instruction destination
* is used as a source for anything.
*/
for (unsigned i = 0; i < opcode->NumSrcRegs; i++) {
if (cur->U.I.SrcReg[i].File == orig_dst_file &&
cur->U.I.SrcReg[i].Index == orig_dst_reg)
return 0;
}
if (cur->U.I.Opcode == RC_OPCODE_MOV &&
cur->U.I.DstReg.File == orig_dst_file &&
cur->U.I.DstReg.Index == orig_dst_reg &&
(cur->U.I.DstReg.WriteMask & orig_dst_wmask) == 0) {
/* We can merge the movs if one of them is from inline constant */
if (cur->U.I.SrcReg[0].File == RC_FILE_NONE ||
orig_src_file == RC_FILE_NONE) {
cur->U.I.DstReg.WriteMask |= orig_dst_wmask;
if (cur->U.I.SrcReg[0].File == RC_FILE_NONE) {
cur->U.I.SrcReg[0].File = orig_src_file;
cur->U.I.SrcReg[0].Index = orig_src_reg;
cur->U.I.SrcReg[0].Abs = inst->U.I.SrcReg[0].Abs;
cur->U.I.SrcReg[0].RelAddr = inst->U.I.SrcReg[0].RelAddr;
}
cur->U.I.SrcReg[0].Swizzle =
merge_swizzles(cur->U.I.SrcReg[0].Swizzle,
inst->U.I.SrcReg[0].Swizzle);
cur->U.I.SrcReg[0].Negate |= inst->U.I.SrcReg[0].Negate;
/* finally delete the original mov */
rc_remove_instruction(inst);
return 1;
}
}
}
return 0;
}
void rc_optimize(struct radeon_compiler * c, void *user)
{
struct rc_instruction * inst = c->Program.Instructions.Next;
@ -900,6 +980,8 @@ void rc_optimize(struct radeon_compiler * c, void *user)
continue;
if (cur->U.I.Opcode == RC_OPCODE_MOV) {
if (merge_movs(c,cur))
continue;
copy_propagate(c, cur);
/* cur may no longer be part of the program */
}