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Delete the entire "x64 Unwinding of an ARM64EC function" section. #4220

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Oct 14, 2022
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Delete the entire "x64 Unwinding of an ARM64EC function" section. #4220

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6 changes: 0 additions & 6 deletions docs/build/arm64ec-windows-abi-conventions.md
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Expand Up @@ -166,12 +166,6 @@ When the helper then returns to the thunk, the thunk:
1. Pops the ARM64EC `lr` register
1. Executes an ARM64 `ret lr` instruction.

## x64 Unwinding of an ARM64EC function

### Recovering the return address

At the beginning of an x64 function, the stack pointer points to the return address that was pushed onto the stack by the caller's `call` instruction. In contrast, at the beginning of an ARM64EC function, the return address is in the `lr` register, set by the caller's `bl` instruction. Therefore, when unwinding the deepest frame of a stack, if the frame corresponds to an ARM64EC function, the x64 unwinder must recreate the value of ARM64EC `lr` by reading the value stashed in the x87 registers when the exception occurred. In addition, the new x64 unwind code `UWOP_SAVE_RET` handles the prolog saving ARM64EC `lr` to the stack.

## ARM64EC function name decoration

An ARM64EC function name has a secondary decoration applied after any language-specific decoration. For functions with C linkage (whether compiled as C or by using `extern "C"`), a `#` is prepended to the name. For C++ decorated functions, a `$$h` tag is inserted into the name.
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