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aco/spill: Create linear VGPRs for spilling ABI-preserved SGPRs

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Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/38281>
This commit is contained in:
Natalie Vock 2025-02-17 23:56:30 +01:00 • committed by Marge Bot
parent 6b2e766617
commit 6616f25e43
1 changed files with 58 additions and 1 deletions
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59
src/amd/compiler/aco_spill.cpp
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@ -1727,6 +1727,64 @@ spill(Program* program)
program->progress = CompilationProgress::after_spilling;
const RegisterDemand limit = get_addr_regs_from_waves(program, program->min_waves);
if (program->is_callee) {
BITSET_DECLARE(preserved_regs, 512);
RegisterDemand callee_limit = RegisterDemand();
program->callee_abi.preservedRegisters(preserved_regs);
for (int16_t i = 0; i < 512; ++i) {
if (i < 256 && i >= limit.sgpr)
i = 256;
if (i >= 256 + limit.vgpr)
break;
if (BITSET_TEST(preserved_regs, i))
continue;
if (i < 256)
++callee_limit.sgpr;
else
++callee_limit.vgpr;
}
auto return_it = std::find_if(
program->blocks.back().instructions.rbegin(), program->blocks.back().instructions.rend(),
[](const auto& instruction) { return instruction->opcode == aco_opcode::p_return; });
if (limit.sgpr > callee_limit.sgpr && return_it != program->blocks.back().instructions.rend()) {
aco_ptr<Instruction>& old_startpgm = program->blocks.front().instructions.front();
Instruction* new_startpgm = create_instruction(aco_opcode::p_startpgm, Format::PSEUDO, 0,
old_startpgm->definitions.size() + 1);
for (unsigned i = 0; i < old_startpgm->definitions.size(); ++i)
new_startpgm->definitions[i] = old_startpgm->definitions[i];
unsigned abi_sgpr_spills = limit.sgpr - callee_limit.sgpr;
Temp abi_sgpr_spill_space = program->allocateTmp(
RegClass(RegType::vgpr, DIV_ROUND_UP(abi_sgpr_spills, program->wave_size)).as_linear());
new_startpgm->definitions.back() = Definition(abi_sgpr_spill_space);
old_startpgm = aco_ptr<Instruction>(new_startpgm);
for (auto& block : program->blocks) {
auto reload = std::find_if(block.instructions.rbegin(), block.instructions.rend(),
[](const auto& instr)
{
return instr->opcode == aco_opcode::p_return ||
instr->opcode == aco_opcode::p_reload_preserved ||
instr->opcode == aco_opcode::p_logical_end;
});
/* If we encounter p_logical_end, we know there is no reload in the block so we can
* skip searching the other instructions.
*/
if (reload == block.instructions.rend() ||
(*reload)->opcode == aco_opcode::p_logical_end)
continue;
(*reload)->operands[0] = Operand(abi_sgpr_spill_space);
}
/* TODO: update live var analysis in-place */
live_var_analysis(program);
}
}
/* no spilling when register pressure is low enough */
if (program->num_waves > 0)
return;
@ -1736,7 +1794,6 @@ spill(Program* program)
/* calculate target register demand */
const RegisterDemand demand = program->max_reg_demand; /* current max */
const RegisterDemand limit = get_addr_regs_from_waves(program, program->min_waves);
uint16_t extra_vgprs = 0;
uint16_t extra_sgprs = 0;