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aco/assembler: align loops if it reduces the number of cache lines

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This is especially beneficial on GFX6-9.

Totals from 11229 (8.46% of 132726) affected shaders: GFX11

CodeSize: 109608640 -> 109840916 (+0.21%)
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/23748>
This commit is contained in:
Daniel Schürmann 2023-06-20 19:03:35 +02:00 • committed by Marge Bot
parent de8ecc127e
commit b9c5b273b0
1 changed files with 30 additions and 0 deletions
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30
src/amd/compiler/aco_assembler.cpp
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@ -48,6 +48,7 @@ struct asm_context {
std::map<unsigned, constaddr_info> constaddrs;
std::map<unsigned, constaddr_info> resumeaddrs;
std::vector<struct aco_symbol>* symbols;
Block* loop_header;
const int16_t* opcode;
// TODO: keep track of branch instructions referring blocks
// and, when emitting the block, correct the offset in instr
@ -1220,6 +1221,35 @@ fix_constaddrs(asm_context& ctx, std::vector<uint32_t>& out)
void
align_block(asm_context& ctx, std::vector<uint32_t>& code, Block& block)
{
if (block.kind & block_kind_loop_exit && ctx.loop_header) {
Block* loop_header = ctx.loop_header;
ctx.loop_header = NULL;
std::vector<uint32_t> nops;
const unsigned loop_num_cl = DIV_ROUND_UP(block.offset - loop_header->offset, 16);
const unsigned loop_start_cl = loop_header->offset >> 4;
const unsigned loop_end_cl = (block.offset - 1) >> 4;
/* Align the loop if it fits into a single cache line or if we can
* reduce the number of cache lines with less than 8 NOPs.
*/
const bool align_loop = loop_end_cl - loop_start_cl >= loop_num_cl &&
(loop_num_cl == 1 || loop_header->offset % 16 > 8);
if (align_loop) {
nops.resize(16 - (loop_header->offset % 16), 0xbf800000u);
insert_code(ctx, code, loop_header->offset, nops.size(), nops.data());
}
}
if (block.kind & block_kind_loop_header) {
/* In case of nested loops, only handle the inner-most loops in order
* to not break the alignment of inner loops by handling outer loops.
* Also ignore loops without back-edge.
*/
ctx.loop_header = block.linear_preds.size() > 1 ? &block : NULL;
}
/* align resume shaders with cache line */
if (block.kind & block_kind_resume) {
size_t cache_aligned = align(code.size(), 16);