Author: Jason Molenda Date: 2019-12-11T12:00:16-08:00 New Revision: 6d64162a2d0df2230faf02ff7ee677c448faf4af
URL: https://github.com/llvm/llvm-project/commit/6d64162a2d0df2230faf02ff7ee677c448faf4af DIFF: https://github.com/llvm/llvm-project/commit/6d64162a2d0df2230faf02ff7ee677c448faf4af.diff LOG: return-object-by-reference ("non trivial") xfail on arm64 in TestTrivialABI.py I don't think this test case can be handled correctly on AAPCS64. The ABI says that the caller passes the address of the return object in x8. x8 is a caller-spilled (aka "volatile") register, and the function is not required to preserve x8 or to copy the address back into x8 on function exit like the SysV x86_64 ABI does with rax. (from aapcs64: "there is no requirement for the callee to preserve the value stored in x8") From my quick reading of ABISysV_arm64, I worry that it may actually be using the value in x8 at function exit, assuming it still has the address of the return object - if (is_return_value) { // We are assuming we are decoding this immediately after returning from // a function call and that the address of the structure is in x8 reg_info = reg_ctx->GetRegisterInfoByName("x8", 0); This will work on trivial test programs / examples, but if the function does another function call, or overwrites x8 as a scratch register, lldb will provide incorrect values to the user. ABIMacOSX_arm64 doesn't do this, but it also doesn't flag the value as unavailable so we're providing incorrect values to the user all the time. I expect my fix will be to make ABIMacOSX_arm64 flag the return value as unretrievable, unless I've misread the ABI. Added: Modified: lldb/packages/Python/lldbsuite/test/lang/cpp/trivial_abi/TestTrivialABI.py lldb/packages/Python/lldbsuite/test/lang/cpp/trivial_abi/main.cpp lldb/source/Plugins/ABI/MacOSX-arm64/ABIMacOSX_arm64.cpp Removed: ################################################################################ diff --git a/lldb/packages/Python/lldbsuite/test/lang/cpp/trivial_abi/TestTrivialABI.py b/lldb/packages/Python/lldbsuite/test/lang/cpp/trivial_abi/TestTrivialABI.py index 78f7fa3afd73..27cf324baeca 100644 --- a/lldb/packages/Python/lldbsuite/test/lang/cpp/trivial_abi/TestTrivialABI.py +++ b/lldb/packages/Python/lldbsuite/test/lang/cpp/trivial_abi/TestTrivialABI.py @@ -31,6 +31,7 @@ def test_call_trivial(self): @expectedFailureAll(oslist=["windows"], bugnumber="llvm.org/pr36870") @expectedFailureAll(archs=["aarch64"], oslist=["linux"], bugnumber="llvm.org/pr44161") + @expectedFailureAll(archs=["arm64", "arm64e"], bugnumber="<rdar://problem/57844240>") def test_call_nontrivial(self): """Test that we can print a variable & call a function on the same class w/o the trivial ABI marker.""" self.build() diff --git a/lldb/packages/Python/lldbsuite/test/lang/cpp/trivial_abi/main.cpp b/lldb/packages/Python/lldbsuite/test/lang/cpp/trivial_abi/main.cpp index cdf593e8b403..b1f50159692a 100644 --- a/lldb/packages/Python/lldbsuite/test/lang/cpp/trivial_abi/main.cpp +++ b/lldb/packages/Python/lldbsuite/test/lang/cpp/trivial_abi/main.cpp @@ -29,7 +29,7 @@ main() outVal = takeTrivial(inVal); S_NotTrivial inNotVal, outNotVal; - outNotVal = takeNotTrivial(outNotVal); + outNotVal = takeNotTrivial(inNotVal); return 0; // Set another for return value } diff --git a/lldb/source/Plugins/ABI/MacOSX-arm64/ABIMacOSX_arm64.cpp b/lldb/source/Plugins/ABI/MacOSX-arm64/ABIMacOSX_arm64.cpp index 6473ccf9a19a..ec7588dfb50c 100644 --- a/lldb/source/Plugins/ABI/MacOSX-arm64/ABIMacOSX_arm64.cpp +++ b/lldb/source/Plugins/ABI/MacOSX-arm64/ABIMacOSX_arm64.cpp @@ -2020,6 +2020,8 @@ bool ABIMacOSX_arm64::CreateDefaultUnwindPlan(UnwindPlan &unwind_plan) { // registers x19 through x28 and sp are callee preserved. v8-v15 are non- // volatile (and specifically only the lower 8 bytes of these regs), the rest // of the fp/SIMD registers are volatile. +// +// v. https://github.com/ARM-software/software-standards/blob/master/abi/aapcs64/ // We treat x29 as callee preserved also, else the unwinder won't try to // retrieve fp saves. _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits