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aco: ignore parallelcopies to the same register on jump threading 

The more conservative lowering to CSSA inserts unnecessary parallelcopies
which might get coalesced and can be ignored on jump threading.

v2: outline is_empty_block() check.

Reviewed-by: Rhys Perry <pendingchaos02@gmail.com>
Tested-by: Marge Bot <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3385>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3385>
This commit is contained in:
Daniel Schürmann 2020-01-14 13:14:38 +01:00
parent 427e5eeb02
commit 3bca0af25d
1 changed files with 38 additions and 31 deletions
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69
src/amd/compiler/aco_ssa_elimination.cpp
View File

@ -111,6 +111,35 @@ void insert_parallelcopies(ssa_elimination_ctx& ctx)
}
}
bool is_empty_block(Block* block, bool ignore_exec_writes)
{
/* check if this block is empty and the exec mask is not needed */
for (aco_ptr<Instruction>& instr : block->instructions) {
switch (instr->opcode) {
case aco_opcode::p_linear_phi:
case aco_opcode::p_phi:
case aco_opcode::p_logical_start:
case aco_opcode::p_logical_end:
case aco_opcode::p_branch:
break;
case aco_opcode::p_parallelcopy:
for (unsigned i = 0; i < instr->definitions.size(); i++) {
if (ignore_exec_writes && instr->definitions[i].physReg() == exec)
continue;
if (instr->definitions[i].physReg() != instr->operands[i].physReg())
return false;
}
break;
case aco_opcode::s_andn2_b64:
case aco_opcode::s_andn2_b32:
if (ignore_exec_writes && instr->definitions[0].physReg() == exec)
break;
default:
return false;
}
}
return true;
}
void try_remove_merge_block(ssa_elimination_ctx& ctx, Block* block)
{
@ -120,22 +149,9 @@ void try_remove_merge_block(ssa_elimination_ctx& ctx, Block* block)
!(ctx.program->blocks[block->linear_succs[0]].kind & block_kind_merge))
return;
/* check if this block is empty and the exec mask is not needed */
for (aco_ptr<Instruction>& instr : block->instructions) {
if (instr->opcode == aco_opcode::p_parallelcopy) {
if (instr->definitions[0].physReg() == exec)
continue;
else
return;
}
if (instr->opcode != aco_opcode::p_linear_phi &&
instr->opcode != aco_opcode::p_phi &&
instr->opcode != aco_opcode::p_logical_start &&
instr->opcode != aco_opcode::p_logical_end &&
instr->opcode != aco_opcode::p_branch)
return;
}
/* check if this block is empty */
if (!is_empty_block(block, true))
return;
/* keep the branch instruction and remove the rest */
aco_ptr<Instruction> branch = std::move(block->instructions.back());
@ -146,18 +162,13 @@ void try_remove_merge_block(ssa_elimination_ctx& ctx, Block* block)
void try_remove_invert_block(ssa_elimination_ctx& ctx, Block* block)
{
assert(block->linear_succs.size() == 2);
/* only remove this block if the successor got removed as well */
if (block->linear_succs[0] != block->linear_succs[1])
return;
/* check if we can remove this block */
for (aco_ptr<Instruction>& instr : block->instructions) {
if (instr->opcode != aco_opcode::p_linear_phi &&
instr->opcode != aco_opcode::p_phi &&
(instr->opcode != aco_opcode::s_andn2_b64 || ctx.program->wave_size != 64) &&
(instr->opcode != aco_opcode::s_andn2_b32 || ctx.program->wave_size != 32) &&
instr->opcode != aco_opcode::p_branch)
return;
}
/* check if block is otherwise empty */
if (!is_empty_block(block, true))
return;
unsigned succ_idx = block->linear_succs[0];
assert(block->linear_preds.size() == 2);
@ -179,12 +190,8 @@ void try_remove_invert_block(ssa_elimination_ctx& ctx, Block* block)
void try_remove_simple_block(ssa_elimination_ctx& ctx, Block* block)
{
for (aco_ptr<Instruction>& instr : block->instructions) {
if (instr->opcode != aco_opcode::p_logical_start &&
instr->opcode != aco_opcode::p_logical_end &&
instr->opcode != aco_opcode::p_branch)
return;
}
if (!is_empty_block(block, false))
return;
Block& pred = ctx.program->blocks[block->linear_preds[0]];
Block& succ = ctx.program->blocks[block->linear_succs[0]];