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Also override the global new operators to assert unconditionally, to catch this common pitfall proactively.
Ideally that would be a compile time diagnostic, but I could not figure out how to make that happen.

Fix #120285

Also override the global new operators to assert unconditionally, to
catch this common pitfall proactively.
@github-actions github-actions bot added the area-CodeGen-coreclr CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI label Oct 1, 2025
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In the single-file host, the Jit is going to be linked statically with the rest of the native code. Is the fact this override is not causing problems in that case by construction or accidental?

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In the single-file host, the Jit is going to be linked statically with the rest of the native code. Is the fact this override is not causing problems in that case by construction or accidental?

Accidental. Let me hide it under a define set for the standalone jits.

@jakobbotsch jakobbotsch marked this pull request as ready for review October 1, 2025 15:01
Copilot AI review requested due to automatic review settings October 1, 2025 15:01
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PTAL @dotnet/jit-contrib. I want to backport this to GA, but might not backport the "diagnostic" new override.

@jakobbotsch jakobbotsch requested a review from a team October 1, 2025 15:02
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Pull Request Overview

This PR aims to eliminate unintended heap allocations in the JIT by routing allocations through the JIT's custom allocators and by asserting on any accidental use of the global operator new in standalone builds.

  • Replaces raw global new usages with allocator-aware placement new for LSRA structures.
  • Introduces overridden global operator new/delete (guarded by JIT_STANDALONE_BUILD) that assert to catch unintended allocations.
  • Adds a build define to enable the new checks.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 6 comments.

File Description
src/coreclr/jit/lsra.cpp Switches allocations to use compiler memory kinds via placement new.
src/coreclr/jit/alloc.cpp Adds global operator new/delete overrides to assert on unintended allocations.
src/coreclr/jit/CMakeLists.txt Defines JIT_STANDALONE_BUILD to enable the new allocation assertions.

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
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LGTM assuming CI passes

@jakobbotsch jakobbotsch merged commit 77fe5dc into dotnet:main Oct 2, 2025
117 checks passed
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/backport to release/10.0

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github-actions bot commented Oct 2, 2025

Started backporting to release/10.0: https://github.com/dotnet/runtime/actions/runs/18188174550

@jakobbotsch jakobbotsch deleted the fix-120285 branch October 2, 2025 08:54
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Unmanaged memory leak in clrjit (amd64) in .NET 10 RC1

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