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bug#42360: [feature/native-comp] miscompilation(?) of functions with non
From: |
Andrea Corallo |
Subject: |
bug#42360: [feature/native-comp] miscompilation(?) of functions with non local exits |
Date: |
Wed, 15 Jul 2020 08:24:00 +0000 |
Due to a recent modification native-comp is (probably?) miscompiling
lexical scope functions with non local exits if they involve code with
side effect on local variables. Before fixing I prefer to double check
the correct behavior we want.
Considering the following piece of (lexical scoped) code:
===
(let (x)
(ignore-errors
(setq x t)
(error "foo"))
x)
===
Three options:
1- Because setq is evaluated the expression should always evaluate to
t.
2- Unwinding the original state of the stack is restored, when it was
saved 'x' was nil so the expression should evaluate to nil.
3- This is unspecified.
The current stock implementaion does always 1 so I'm prone to just go
for it but I wanted to double check to be on the safe side.
FYI 1 implies C register variables cannot be used to implement Lisp
local variable if non local exits are present.
Thanks
Andrea
--
akrl@sdf.org
- bug#42360: [feature/native-comp] miscompilation(?) of functions with non local exits,
Andrea Corallo <=