From 74ca6191fa0dbbe8cee3dc53741b8d59fbf16b09 Mon Sep 17 00:00:00 2001 From: normalcoder <normalcoder@gmail.com> Date: Sun, 19 Dec 2021 00:12:08 +0300 Subject: [PATCH] ncg/aarch64: Don't use x18 register on AArch64/Darwin MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Apple's ABI documentation [1] says: "The platforms reserve register x18. Don’t use this register." While this wasn't problematic in previous Darwin releases, macOS 13 appears to start zeroing this register periodically. See #21964. [1] https://developer.apple.com/documentation/xcode/writing-arm64-code-for-apple-platforms (cherry picked from commit 67575f2004340564d6e52af055ed6fb43d3f9711) --- docs/users_guide/9.2.5-notes.rst | 2 ++ includes/CodeGen.Platform.hs | 8 ++++++++ 2 files changed, 10 insertions(+) diff --git a/docs/users_guide/9.2.5-notes.rst b/docs/users_guide/9.2.5-notes.rst index fca1f59d1747..54e5a1a2c656 100644 --- a/docs/users_guide/9.2.5-notes.rst +++ b/docs/users_guide/9.2.5-notes.rst @@ -21,6 +21,8 @@ Compiler - Fix a code generation panic when using SIMD types with unboxed sums (:ghc-ticket:`22187`). +- Fix a code generation bug with the native code generator on aarch64 darwin leading to runtime segmentation faults due to an incorrect ABI (:ghc-ticket:`21964`) + Runtime system -------------- diff --git a/includes/CodeGen.Platform.hs b/includes/CodeGen.Platform.hs index 0dfac62a3f12..ebec0212bd0f 100644 --- a/includes/CodeGen.Platform.hs +++ b/includes/CodeGen.Platform.hs @@ -1028,6 +1028,14 @@ freeReg 29 = False -- ip0 -- used for spill offset computations freeReg 16 = False +#if defined(darwin_HOST_OS) || defined(ios_HOST_OS) +-- x18 is reserved by the platform on Darwin/iOS, and can not be used +-- More about ARM64 ABI that Apple platforms support: +-- https://developer.apple.com/documentation/xcode/writing-arm64-code-for-apple-platforms +-- https://github.com/Siguza/ios-resources/blob/master/bits/arm64.md +freeReg 18 = False +#endif + # if defined(REG_Base) freeReg REG_Base = False # endif -- GitLab