> Implementation of "Foreign Function & Memory API" for linux on Power (Little > Endian) according to "Power Architecture 64-Bit ELF V2 ABI Specification". > > This PR does not include code for VaList support because it's supposed to get > removed by [JDK-8299736](https://bugs.openjdk.org/browse/JDK-8299736). I've > kept the related tests disabled for this platform and throw an exception > instead. Note that the ABI doesn't precisely specify variable argument lists. > Instead, it refers to `<stdarg.h>` (2.2.4 Variable Argument Lists). > > Big Endian support is implemented to some extend, but not complete. E.g. > structs with size not divisible by 8 are not passed correctly (see `useABIv2` > in CallArranger.java). Big Endian is excluded by selecting > `ARCH.equals("ppc64le")` (CABI.java) only. > > There's another limitation: This PR only accepts structures with size > divisible by 4. (An `IllegalArgumentException` gets thrown otherwise.) I > think arbitrary sizes are not usable on other platforms, either, because > `SharedUtils.primitiveCarrierForSize` only accepts powers of 2. > > The ABI has some tricky corner cases related to HFA (Homogeneous Float > Aggregate). The same argument may need to get passed in both, a FP reg and a > GP reg or stack slot (see "no partial DW rule"). This cases are not covered > by the existing tests. > > I had to make changes to shared code and code for other platforms: > 1. Pass type information when creating `VMStorage` objects from `VMReg`. This > is needed for the following reasons: > - PPC64 ABI requires integer types to get extended to 64 bit (also see > CCallingConventionRequiresIntsAsLongs in existing hotspot code). We need to > know the type or at least the bit width for that. > - Floating point load / store instructions need the correct width to select > between the correct IEEE 754 formats. The register representation in single > FP registers is always IEEE 754 double precision on PPC64. > - Big Endian also needs usage of the precise size. Storing 8 Bytes and > loading 4 Bytes yields different values than on Little Endian! > 2. It happens that a `NativeMemorySegmentImpl` is used as a raw pointer (with > byteSize() == 0) while running TestUpcallScope. Hence, existing size checks > don't work (see MemorySegment.java). As a workaround, I'm just skipping the > check in this particular case. Please check if this makes sense or if there's > a better fix (possibly as separate RFE).
Martin Doerr has updated the pull request incrementally with one additional commit since the last revision: HFA: Add support for nested structures. See JDK-8300294. ------------- Changes: - all: https://git.openjdk.org/jdk/pull/12708/files - new: https://git.openjdk.org/jdk/pull/12708/files/a4d844f7..b461d80c Webrevs: - full: https://webrevs.openjdk.org/?repo=jdk&pr=12708&range=03 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12708&range=02-03 Stats: 37 lines in 2 files changed: 24 ins; 0 del; 13 mod Patch: https://git.openjdk.org/jdk/pull/12708.diff Fetch: git fetch https://git.openjdk.org/jdk pull/12708/head:pull/12708 PR: https://git.openjdk.org/jdk/pull/12708
