Avoid pointer offsets for JIT relocation targets#13772
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Signed-off-by: Hugh Ryan <197298026+HueCodes@users.noreply.github.com>
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| let mut next_veneer_idx = 0; | ||
| let relocation_target_addr = |name: &ModuleRelocTarget, addend: Addend| { | ||
| let addend = isize::try_from(addend).unwrap(); | ||
| get_address(name).addr().checked_add_signed(addend).unwrap() |
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This should have used expose_provenance, not addr. addr() doesn't allow dereferencing the address after turning it back into a pointer, yet that is exactly what the JITed code will likely do.
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Thanks for the feedback. This is good learning for me. That makes sense: these relocation values are not just opaque integers for comparison or range math. They can become addresses that JITed code later uses as pointers, so using I prepared a follow-up that switches this helper to |
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Fixes #7588.
CompiledBlob::perform_relocations` computed relocation targets with unsafe pointer offsets, then cast those pointers back to integers for relocation math.
This computes checked numeric target addresses up front with
ptr.addr().checked_add_signed(...). The relocation math stays the same and unlike #8041 this does not usewrapping_offset.Tested with
cargo test -p cranelift-jit,cargo clippy -p cranelift-jit --all-targets --all-features -- -D warnings, and Cranelift filetests.