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- From 903a79a1efff18fc7cc50db09a3fe5d768adc9a8 Mon 19 Mar 2018 09:58:06 +0100
- From: Lars T Hansen <lhansen@mozilla.com>
- Date: Fri, 23 Mar 2018 22:01:33 +0000
- Subject: [PATCH] save and restore non-volatile x28 on ARM64 for generated unboxed object constructor
- Fixes: https://bugzilla.mozilla.org/show_bug.cgi?id=1375074
- Upsream-status: Applied
- See: https://hg.mozilla.org/mozilla-central/rev/800abe66894d
- Signed-off-by: Lars T Hansen <lhansen@mozilla.com>
- Signed-off-by: Adam Duskett <aduskett@gmail.com>
- ---
- js/src/vm/UnboxedObject.cpp | 30 ++++++++++++++++++++++++++----
- 1 file changed, 26 insertions(+), 4 deletions(-)
- diff --git a/js/src/vm/UnboxedObject.cpp b/js/src/vm/UnboxedObject.cpp
- index 35ca20d7405f..1c20a1093d13 100644
- --- a/js/src/vm/UnboxedObject.cpp
- +++ b/js/src/vm/UnboxedObject.cpp
- @@ -86,9 +86,16 @@ static const uintptr_t CLEAR_CONSTRUCTOR_CODE_TOKEN = 0x1;
- #endif
- #ifdef JS_CODEGEN_ARM64
- - // ARM64 communicates stack address via sp, but uses a pseudo-sp for
- - // addressing.
- - masm.initStackPtr();
- + // ARM64 communicates stack address via sp, but uses a pseudo-sp (PSP) for
- + // addressing. The register we use for PSP may however also be used by
- + // calling code, and it is nonvolatile, so save it. Do this as a special
- + // case first because the generic save/restore code needs the PSP to be
- + // initialized already.
- + MOZ_ASSERT(PseudoStackPointer64.Is(masm.GetStackPointer64()));
- + masm.Str(PseudoStackPointer64, vixl::MemOperand(sp, -16, vixl::PreIndex));
- +
- + // Initialize the PSP from the SP.
- + masm.initStackPtr();
- #endif
- MOZ_ASSERT(propertiesReg.volatile_());
- @@ -239,7 +246,22 @@ static const uintptr_t CLEAR_CONSTRUCTOR_CODE_TOKEN = 0x1;
- if (ScratchDoubleReg.volatile_()) masm.pop(ScratchDoubleReg);
- masm.PopRegsInMask(savedNonVolatileRegisters);
- - masm.abiret();
- +#ifdef JS_CODEGEN_ARM64
- + // Now restore the value that was in the PSP register on entry, and return.
- +
- + // Obtain the correct SP from the PSP.
- + masm.Mov(sp, PseudoStackPointer64);
- +
- + // Restore the saved value of the PSP register, this value is whatever the
- + // caller had saved in it, not any actual SP value, and it must not be
- + // overwritten subsequently.
- + masm.Ldr(PseudoStackPointer64, vixl::MemOperand(sp, 16, vixl::PostIndex));
- +
- + // Perform a plain Ret(), as abiret() will move SP <- PSP and that is wrong.
- + masm.Ret(vixl::lr);
- +#else
- + masm.abiret();
- +#endif
- masm.bind(&failureStoreOther);
- --
- 2.23.0
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