| author |  Matthew Lugg <mlugg@mlugg.co.uk> 2025-02-05 20:33:39+00:00 |
| committer | Matthew Lugg <mlugg@mlugg.co.uk> 2025-02-05 21:17:40+00:00 |
| log | fbbf34e563a376ea1654dce827b9194ba7211b3a |
| tree | dc95e30f87d14c2ff3b3784df76ed10327f4425a |
| parent | cac814cf58ca65ffd8081dca6f2f5b26d822ef5d |
| signature |  Commit is signed but in an unrecognized format. |
Sema: disable runtime safety checks in comptime blocks
Sometimes we emit runtime instructions in comptime scopes. These
instructions will be discarded, but they allow comptime blocks to
contain intermediate runtime-known values, which is necessary for
expressions like `runtime_array.len` to work.
Since we will always throw away these runtime instructions, including
safety checks is a time waste at best and trips an assertion at worst!
Resolves: #200642 files changed, 24 insertions(+), 3 deletions(-)
src/Sema.zig+13-3
| ... | ... | @@ -504,7 +504,17 @@ pub const Block = struct { |
| 504 | 504 | }; |
| 505 | 505 | } |
| 506 | 506 | |
| 507 | pub fn wantSafety(block: *const Block) bool { | |
| 507 | fn wantSafeTypes(block: *const Block) bool { | |
| 508 | return block.want_safety orelse switch (block.sema.pt.zcu.optimizeMode()) { | |
| 509 | .Debug => true, | |
| 510 | .ReleaseSafe => true, | |
| 511 | .ReleaseFast => false, | |
| 512 | .ReleaseSmall => false, | |
| 513 | }; | |
| 514 | } | |
| 515 | ||
| 516 | fn wantSafety(block: *const Block) bool { | |
| 517 | if (block.isComptime()) return false; // runtime safety checks are pointless in comptime blocks | |
| 508 | 518 | return block.want_safety orelse switch (block.sema.pt.zcu.optimizeMode()) { |
| 509 | 519 | .Debug => true, |
| 510 | 520 | .ReleaseSafe => true, |
| ... | ... | @@ -3294,7 +3304,7 @@ fn zirUnionDecl( |
| 3294 | 3304 | .tagged |
| 3295 | 3305 | else if (small.layout != .auto) |
| 3296 | 3306 | .none |
| 3297 | else switch (block.wantSafety()) { | |
| 3307 | else switch (block.wantSafeTypes()) { | |
| 3298 | 3308 | true => .safety, |
| 3299 | 3309 | false => .none, |
| 3300 | 3310 | }, |
| ... | ... | @@ -22219,7 +22229,7 @@ fn reifyUnion( |
| 22219 | 22229 | .tagged |
| 22220 | 22230 | else if (layout != .auto) |
| 22221 | 22231 | .none |
| 22222 | else switch (block.wantSafety()) { | |
| 22232 | else switch (block.wantSafeTypes()) { | |
| 22223 | 22233 | true => .safety, |
| 22224 | 22234 | false => .none, |
| 22225 | 22235 | }, |
test/behavior/eval.zig+11
| ... | ... | @@ -1751,3 +1751,14 @@ test "comptime labeled block implicit exit" { |
| 1751 | 1751 | }; |
| 1752 | 1752 | comptime assert(result == {}); |
| 1753 | 1753 | } |
| 1754 | ||
| 1755 | test "comptime block has intermediate runtime-known values" { | |
| 1756 | const arr: [2]u8 = .{ 1, 2 }; | |
| 1757 | ||
| 1758 | var idx: usize = undefined; | |
| 1759 | idx = 0; | |
| 1760 | ||
| 1761 | comptime { | |
| 1762 | _ = arr[idx]; | |
| 1763 | } | |
| 1764 | } |