Fix: write barrier bypass in setv()/copyv() for STRSXP/VECSXP targets - #877
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setcopyv() wrote element pointers directly into STRSXP/VECSXP backing arrays, skipping R's generational write barrier. On an old-generation target this can leave an unrecorded reference to a younger CHARSXP/list element, which a subsequent young-generation GC may free while still referenced, causing memory corruption, cryptic CHAR()/SET_STRING_ELT() errors, or segfaults. Use SET_STRING_ELT()/SET_VECTOR_ELT() for the boxed-type write loops so the reference is properly recorded, while leaving the numeric/raw branches unchanged. Also drops the omp simd pragma from the boxed write paths, since the barriered setters are function calls and are not safely vectorizable. Co-authored-by: Sebastian Krantz <48053842+SebKrantz@users.noreply.github.com>
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Summary
Fixes #876:
setv()/copyv()wrote element pointers directly into the backing array ofSTRSXP/VECSXPtargets insetcopyv()(src/programming.c), bypassing R's generational write barrier. On an old-generation target this can leave an unrecorded reference to a youngerCHARSXP/list element, which a subsequent young-generation GC may free while still referenced, causing memory corruption, crypticCHAR()/SET_STRING_ELT()errors, or segfaults.SET_STRING_ELT()/SET_VECTOR_ELT()in theSTRSXP/VECSXPwrite loops instead of raw pointer assignment, so the old-to-new reference is properly recorded.omp simdpragma on the boxed-type write path, since the barriered setters are function calls and not safely vectorizable.NEWS.mdentry.Test plan
devtools::test())R CMD checksetv()/copyv()on character and list vectors, including thevind1=TRUEindex-vector pathNote: this PR was authored in a sandbox without an R toolchain, so the change has not been compiled or test-run here.
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