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Fix soundness bug by using currying information from typing#850

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lpw25 merged 6 commits intooxcaml:mainfrom
stedolan:fix-nlocal-zero
Sep 28, 2022
Merged

Fix soundness bug by using currying information from typing#850
lpw25 merged 6 commits intooxcaml:mainfrom
stedolan:fix-nlocal-zero

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Previously, transl_curried_function in Translcore redetected function currying, which is difficult with locals as modes may make it invalid to merge two lambdas into a single n-ary function.

The mode logic here was wrong, leading to a soundness bug. Rather than fix it (which would continue the duplication of mode-checking between typing and transl), the fix here is to add the relevant information to Typedtree, so that Translcore follows the decisions made by typing instead of redetecting currying on its own.

This causes a slight change in closure allocation / caml_apply behaviour, as the currying decisions made by Typedtree do not always exactly match those made by Lambda. For instance, the following is now detected as a two-argument function as the typechecker (unlike Lambda) does not see through the unboxed record:

type 'a unbox = A of 'a [@@unboxed]
let f a b = A (fun c -> a+b+c)

@mshinwell mshinwell added bug Something isn't working typing labels Sep 26, 2022
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Mostly looks good. One place that looks suspicious.

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This now looks safe, but I think it's too strict and doesn't always allocate things locally when it could.

Previously, transl_curried_function in Translcore redetected function
currying, which is difficult with locals as modes may make it invalid
to merge two lambdas into a single n-ary function.

The mode logic here was wrong, leading to a soundness bug. Rather than
fix it (which would continue the duplication of mode-checking between
typing and transl), the fix here is to add the relevant information to
Typedtree, so that Translcore follows the decisions made by typing
instead of redetecting currying on its own.
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LGTM

@lpw25 lpw25 merged commit 08424cc into oxcaml:main Sep 28, 2022
mshinwell added a commit to mshinwell/oxcaml that referenced this pull request Oct 24, 2022
25188da flambda-backend: Missed comment from PR802 (oxcaml#887)
9469765 flambda-backend: Improve the semantics of asynchronous exceptions (new simpler version) (oxcaml#802)
d9e4dd0 flambda-backend: Fix `make runtest` on NixOS (oxcaml#874)
4bbde7a flambda-backend: Simpler symbols (oxcaml#753)
ef37262 flambda-backend: Add opaqueness to Obj.magic under Flambda 2 (oxcaml#862)
a9616e9 flambda-backend: Add build system hooks for ocaml-jst (oxcaml#869)
045ef67 flambda-backend: Allow the compiler to build with stock Dune (oxcaml#868)
3cac5be flambda-backend: Simplify Makefile logic for natdynlinkops (oxcaml#866)
c5b12bf flambda-backend: Remove unnecessary install lines (oxcaml#860)
ff12bbe flambda-backend: Fix unused variable warning in st_stubs.c (oxcaml#861)
c84976c flambda-backend: Static check for noalloc: attributes (oxcaml#825)
ca56052 flambda-backend: Build system refactoring for ocaml-jst (oxcaml#857)
39eb7f9 flambda-backend: Remove integer comparison involving nonconstant polymorphic variants (oxcaml#854)
c102688 flambda-backend: Fix soundness bug by using currying information from typing (oxcaml#850)
6a96b61 flambda-backend: Add a primitive to enable/disable the tick thread (oxcaml#852)
f64370b flambda-backend: Make Obj.dup use a new primitive, %obj_dup (oxcaml#843)
9b78eb2 flambda-backend: Add test for oxcaml#820 (include functor soundness bug) (oxcaml#841)
8f24346 flambda-backend: Add `-dtimings-precision` flag (oxcaml#833)
65c2f22 flambda-backend: Add test for oxcaml#829 (oxcaml#831)
7b27a49 flambda-backend: Follow-up PR#829 (comballoc fixes for locals) (oxcaml#830)
ad7ec10 flambda-backend: Use a custom condition variable implementation (oxcaml#787)
3ee650c flambda-backend: Fix soundness bug in include functor (oxcaml#820)
2f57378 flambda-backend: Static check noalloc (oxcaml#778)
aaad625 flambda-backend: Emit begin/end region only when stack allocation is enabled (oxcaml#812)
17c7173 flambda-backend: Fix .cmt for included signatures (oxcaml#803)
e119669 flambda-backend: Increase delays in tests/lib-threads/beat.ml (oxcaml#800)
ccc356d flambda-backend: Prevent dynamic loading of the same .cmxs twice in private mode, etc. (oxcaml#784)
14eb572 flambda-backend: Make local extension point equivalent to local_ expression (oxcaml#790)
487d11b flambda-backend: Fix tast_iterator and tast_mapper for include functor. (oxcaml#795)
a50a818 flambda-backend: Reduce closure allocation in List (oxcaml#792)
96c9c60 flambda-backend: Merge ocaml-jst
a775b88 flambda-backend: Fix ocaml/otherlibs/unix 32-bit build (oxcaml#767)
f7c2679 flambda-backend: Create object files internally to avoid invoking GAS (oxcaml#757)
c7a46bb flambda-backend: Bugfix for Cmmgen.expr_size with locals (oxcaml#756)
b337cb6 flambda-backend: Fix build_upstream for PR749 (oxcaml#750)
8e7e81c flambda-backend: Differentiate is_int primitive between generic and variant-only versions (oxcaml#749)

git-subtree-dir: ocaml
git-subtree-split: 25188da
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