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| author | Antonio Frighetto <me@antoniofrighetto.com> | 2025-07-02 09:23:22 +0200 |
|---|---|---|
| committer | Antonio Frighetto <me@antoniofrighetto.com> | 2025-07-02 09:29:36 +0200 |
| commit | f1cc0b607b03548028db3ca57bb057b2599b1711 (patch) | |
| tree | bb9c8f0c81f52d3cead1c23ba0a31fde611d697f /llvm/lib/IR/Attributes.cpp | |
| parent | d5608d6751315f2e34a0445ca7f5be44a1520463 (diff) | |
| download | llvm-f1cc0b607b03548028db3ca57bb057b2599b1711.zip llvm-f1cc0b607b03548028db3ca57bb057b2599b1711.tar.gz llvm-f1cc0b607b03548028db3ca57bb057b2599b1711.tar.bz2 | |
[IR] Introduce `dead_on_return` attribute
Add `dead_on_return` attribute, which is meant to be taken advantage
by the frontend, and states that the memory pointed to by the argument
is dead upon function return. As with `byval`, it is supposed to be
used for passing aggregates by value. The difference lies in the ABI:
`byval` implies that the pointer is explicitly passed as argument to
the callee (during codegen the copy is emitted as per byval contract),
whereas a `dead_on_return`-marked argument implies that the copy
already exists in the IR, is located at a specific stack offset within
the caller, and this memory will not be read further by the caller upon
callee return – or otherwise poison, if read before being written.
RFC: https://discourse.llvm.org/t/rfc-add-dead-on-return-attribute/86871.
Diffstat (limited to 'llvm/lib/IR/Attributes.cpp')
| -rw-r--r-- | llvm/lib/IR/Attributes.cpp | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/llvm/lib/IR/Attributes.cpp b/llvm/lib/IR/Attributes.cpp index bfb32ff..d1fbcb9 100644 --- a/llvm/lib/IR/Attributes.cpp +++ b/llvm/lib/IR/Attributes.cpp @@ -2424,7 +2424,8 @@ AttributeMask AttributeFuncs::typeIncompatible(Type *Ty, AttributeSet AS, .addAttribute(Attribute::Writable) .addAttribute(Attribute::DeadOnUnwind) .addAttribute(Attribute::Initializes) - .addAttribute(Attribute::Captures); + .addAttribute(Attribute::Captures) + .addAttribute(Attribute::DeadOnReturn); if (ASK & ASK_UNSAFE_TO_DROP) Incompatible.addAttribute(Attribute::Nest) .addAttribute(Attribute::SwiftError) |