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| author | Björn Gustavsson <[email protected]> | 2018-12-06 13:07:42 +0100 |
|---|---|---|
| committer | Björn Gustavsson <[email protected]> | 2018-12-18 11:40:07 +0100 |
| commit | 1ea57e5498d92b730644cb37b659d16e51f56b4d (patch) | |
| tree | 3464aa1912825e297d0609abe0af8b3eeb1af315 /erts/emulator/beam/ops.tab | |
| parent | 472b0669788e155f28851999b4e60bf8302ca2d5 (diff) | |
| download | otp-1ea57e5498d92b730644cb37b659d16e51f56b4d.tar.gz otp-1ea57e5498d92b730644cb37b659d16e51f56b4d.tar.bz2 otp-1ea57e5498d92b730644cb37b659d16e51f56b4d.zip | |
Make length/1 yielding
The guard BIF `length/1` would calculate the length of the list in one
go without yielding, even if the list was were long. To make it even
worse, the call to `length/1` would only cost a single reduction.
This commit reimplements `length/1` so that it eats a number of
reductions proportional to the length of the list, and yields if the
available reductions run out.
Diffstat (limited to 'erts/emulator/beam/ops.tab')
| -rw-r--r-- | erts/emulator/beam/ops.tab | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/erts/emulator/beam/ops.tab b/erts/emulator/beam/ops.tab index fbed2e56e1..cb414143fc 100644 --- a/erts/emulator/beam/ops.tab +++ b/erts/emulator/beam/ops.tab @@ -1588,6 +1588,17 @@ bif1 Fail u$bif:erlang:round/1 s d => too_old_compiler bif1 Fail u$bif:erlang:trunc/1 s d => too_old_compiler # +# Handle the length/1 guard BIF specially to make it trappable. +# + +gc_bif1 Fail=j Live u$bif:erlang:length/1 Src Dst => \ + i_length_setup Live Src | i_length Fail Live Dst + +i_length_setup t xyc + +i_length j? t d + +# # Guard BIFs. # gc_bif1 p Live Bif Src Dst => i_bif1_body Bif Src Dst |