Disable MSVC runtime stack checks in janet_ffi_win64 #1676
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The MSVC /RTCs argument instrument alloca() to prepend stack allocations with metadata used to check for memory corruption during the function prologue. This causes stack-based FFI arguments in janet_ffi_win64 to become mis-aligned, and also for the alloca()-prepended header to be corrupted leading to a fatal exception.
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Apologies for the fix being based on an older tag, I've got 1.38 vendored into another project. The bug and the fix repro correctly on current master. |
Member
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LGTM, thanks for the fix. I was wondering why MSVC was adding extra padding bytes to the stack when using alloca, and this illustrates one use of that extra space. |
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The MSVC /RTCs argument instruments alloca() to prepend stack allocations with metadata used to check for memory corruption during the function prologue. This causes stack-based FFI arguments in janet_ffi_win64 to become mis-aligned, and also for the alloca()-prepended header to be corrupted leading to a fatal exception.
This change fixes the fatal error (#1675) by disabling /RTCs during janet_ffi_win64 codegen.