On Thu, 22 Apr 2021 08:19:53 GMT, Nick Gasson <ngas...@openjdk.org> wrote:
> macOS on Apple silicon uses slightly different ABI conventions to the > standard AArch64 ABI. The differences are outlined in [1]. In > particular in the standard (AAPCS) ABI, variadic arguments may be passed > in either registers or on the stack following the normal calling > convention. To handle this, va_list is a struct containing separate > pointers for arguments located in integer registers, floating point > registers, and on the stack. Apple's ABI simplifies this by passing all > variadic arguments on the stack and the va_list type becomes a simple > char* pointer. > > This patch adds a new MacOsAArch64 CABI type and MacOsAArch64Linker to > represent the new ABI variant on macOS. StackVaList is based on > WinVaList lightly modified to handle the different TypeClasses on > AArch64. The original AArch64Linker is renamed to AapcsLinker and is > currently used for all non-Mac platforms. I think we also need to add a > WinAArch64 CABI but I haven't yet been able to test on a Windows system > so will do that later. > > The macOS ABI also uses a different method of spilling arguments to the > stack (the standard ABI pads each argument to a multiple of 8 byte stack > slots, but the Mac ABI packs arguments according to their natural > alignment). None of the existing tests exercise this so I'll open a new > JBS issue and work on that separately. > > Tested jdk_foreign on macOS AArch64, Linux AArch64, and Linux X86_64. > > [1] > https://developer.apple.com/documentation/xcode/writing_arm64_code_for_apple_platforms I'll leave fine details to @JornVernee - high level bits seem correct. I think we should be more transparent in e.g. enum constant on the fact that AArch64 really means linux - and perhaps use Arm64 instead of AArch64. src/jdk.incubator.foreign/share/classes/jdk/internal/foreign/CABI.java line 35: > 33: SysV, > 34: Win64, > 35: AArch64, This should be Linux AArch64. Btw, should we use Arm64 instead, which seems to be the more common name to refer to the platform? src/jdk.incubator.foreign/share/classes/jdk/internal/foreign/abi/aarch64/aapcs/AapcsLinker.java line 50: > 48: * the ARM 64-bit Architecture". > 49: */ > 50: public class AapcsLinker implements CLinker { I see why it's called like that - but this is really either AArch64Linker or Arm64Linker. E.g. the platform standard one. src/jdk.incubator.foreign/share/classes/jdk/internal/foreign/abi/aarch64/aapcs/AapcsVaList.java line 54: > 52: * Linux. Variadic parameters may be passed in registers or on the stack. > 53: */ > 54: public class AapcsVaList implements VaList { Same here - not sure I like Aapcs much ------------- PR: https://git.openjdk.java.net/jdk/pull/3617
