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| author | Björn Gustavsson <[email protected]> | 2015-04-21 15:21:48 +0200 |
|---|---|---|
| committer | Björn Gustavsson <[email protected]> | 2015-04-29 12:23:41 +0200 |
| commit | 61eaa7570811d81e2a91d0126461a2dac22786dc (patch) | |
| tree | ac883c774e6d0d637e848b9cb0f152b35edcde75 | |
| parent | 8c32dda686d2b964b08cc4614ba9c445039b3dd9 (diff) | |
| download | otp-61eaa7570811d81e2a91d0126461a2dac22786dc.tar.gz otp-61eaa7570811d81e2a91d0126461a2dac22786dc.tar.bz2 otp-61eaa7570811d81e2a91d0126461a2dac22786dc.zip | |
beam_utils: Be less conservative about liveness for exit instructions
beam_utils used to be overly conservative about liveness for
exit instructions such as:
call_ext erlang:exit/1
beam_utils would consider all y registers to be used, to avoid
overwriting a catch or try tag. That does not seem to be a real
risk.
However, we miss opportunities for stack trimming if we consider
y registers used by an exit instruction.
| -rw-r--r-- | lib/compiler/src/beam_utils.erl | 12 |
1 files changed, 4 insertions, 8 deletions
diff --git a/lib/compiler/src/beam_utils.erl b/lib/compiler/src/beam_utils.erl index fd666be41e..fca13497ba 100644 --- a/lib/compiler/src/beam_utils.erl +++ b/lib/compiler/src/beam_utils.erl @@ -344,14 +344,10 @@ check_liveness(R, [{call_ext,Live,_}=I|Is], St) -> false -> check_liveness(R, Is, St); true -> - %% We must make sure we don't check beyond this instruction - %% or we will fall through into random unrelated code and - %% get stuck in a loop. - %% - %% We don't want to overwrite a 'catch', so consider this - %% register in use. - %% - {used,St} + %% We must make sure we don't check beyond this + %% instruction or we will fall through into random + %% unrelated code and get stuck in a loop. + {killed,St} end end; check_liveness(R, [{call_fun,Live}|Is], St) -> |