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unwind: use a more portable endianness check in EHABI

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The ARM specific code was trying to determine endianness using the
`__LITTLE_ENDIAN__` macro which is not guaranteed to be defined.
When not defined, it makes libunwind to build the big-endian code even
when the compiler builds for a little-endian target.

This change allows building libunwind with the `musl-gcc` toolchain
which does not define `__LITTLE_ENDIAN__`.  Use `__BYTE_ORDER__`
instead.

Patch by Idan Freiberg!
This commit is contained in:
Saleem Abdulrasool
2020-05-29 08:25:35 -07:00
parent 747c574b94
commit 68c50708d1
1 changed files with 8 additions and 4 deletions
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12
libunwind/src/Unwind-EHABI.cpp
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@@ -31,10 +31,12 @@ namespace {
// signinficant byte.
uint8_t getByte(const uint32_t* data, size_t offset) {
const uint8_t* byteData = reinterpret_cast<const uint8_t*>(data);
#ifdef __LITTLE_ENDIAN__
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
return byteData[(offset & ~(size_t)0x03) + (3 - (offset & (size_t)0x03))];
#else
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
return byteData[offset];
#else
#error "Unable to determine endianess"
#endif
}
@@ -943,10 +945,12 @@ _Unwind_VRS_Pop(_Unwind_Context *context, _Unwind_VRS_RegClass regclass,
// SP is only 32-bit aligned so don't copy 64-bit at a time.
uint64_t w0 = *sp++;
uint64_t w1 = *sp++;
#ifdef __LITTLE_ENDIAN__
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
uint64_t value = (w1 << 32) | w0;
#else
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
uint64_t value = (w0 << 32) | w1;
#else
#error "Unable to determine endianess"
#endif
if (_Unwind_VRS_Set(context, regclass, i, representation, &value) !=
_UVRSR_OK)