jimzah/zig
1
0
Fork 0
mirror of https://github.com/ziglang/zig.git synced 2024-11-27 07:32:44 +00:00
Code Issues Actions 1 Packages Projects Releases Wiki Activity

Sema: fix performance regression

Browse Source 
LLVM fails to notice that in release builds, `logFn` ignores its
arguments, so their computation can be elided. So, LLVM fails to elide
this hashmap lookup. Its cost isn't too significant, but doing it in the
hottest loop in Sema adds up!

Technically, we could do the lookup a single time, before the loop, but
it was cleanest (and a little faster) to just disable this log call at
comptime when debug logging is disabled.
This commit is contained in:
mlugg 2024-06-20 08:38:23 +01:00
parent 6a8cf25a8a
commit 2b677d1660
No known key found for this signature in database
GPG Key ID: 3F5B7DCCBF4AF02E
1 changed files with 10 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
src/Sema.zig
View File

@ -992,11 +992,16 @@ fn analyzeBodyInner(
while (true) { while (true) {
crash_info.setBodyIndex(i); crash_info.setBodyIndex(i);
const inst = body[i]; const inst = body[i];
std.log.scoped(.sema_zir).debug("sema ZIR {s} %{d}", .{ sub_file_path: {
const path_digest = block.src_base_inst.resolveFull(&mod.intern_pool).path_digest; // The hashmap lookup in here is a little expensive, and LLVM fails to optimize it away.
const index = mod.path_digest_map.getIndex(path_digest).?; if (build_options.enable_logging) {
break :sub_file_path mod.import_table.values()[index].sub_file_path; std.log.scoped(.sema_zir).debug("sema ZIR {s} %{d}", .{ sub_file_path: {
}, inst }); const path_digest = block.src_base_inst.resolveFull(&mod.intern_pool).path_digest;
const index = mod.path_digest_map.getIndex(path_digest).?;
break :sub_file_path mod.import_table.values()[index].sub_file_path;
}, inst });
}
const air_inst: Air.Inst.Ref = switch (tags[@intFromEnum(inst)]) { const air_inst: Air.Inst.Ref = switch (tags[@intFromEnum(inst)]) {
// zig fmt: off // zig fmt: off
.alloc => try sema.zirAlloc(block, inst), .alloc => try sema.zirAlloc(block, inst),