Fix Enzyme autodiff ICE by anchoring metadata markers in core#155059
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purahan wants to merge 1 commit intorust-lang:mainfrom
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Fix Enzyme autodiff ICE by anchoring metadata markers in core#155059purahan wants to merge 1 commit intorust-lang:mainfrom
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Fixes a crash where Enzyme fails to compute derivatives when compiling with LTO. Previously, global metadata markers (like `enzyme_dup`) were declared in the LLVM backend (`rustc_codegen_llvm`). However, LLVM's Link-Time Optimization aggressively stripped their initializers, causing Enzyme to misinterpret them as active external variables rather than constant structural markers. This fix resolves the issue by defining these structural anchors directly within the `core` library as `#[no_mangle]` statics. By anchoring them in the standard library, they are natively protected from LTO stripping, ensuring Enzyme correctly parses them as constant metadata during derivative generation.
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Fixes a crash where Enzyme fails to compute derivatives when compiling with LTO. Previously, global metadata markers (like
enzyme_dup) were declared in the LLVM backend (rustc_codegen_llvm). However, LLVM's Link-Time Optimization aggressively stripped their initializers, causing Enzyme to misinterpret them as active external variables rather than constant structural markers.This fix resolves the issue by defining these structural anchors directly within the
corelibrary as#[no_mangle]statics. By anchoring them in the standard library, they are natively protected from LTO stripping, ensuring Enzyme correctly parses them as constant metadata during derivative generation.