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Merge commit 221c5af4e from llvm git (by Nico Weber):

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Fix a -Wbitwise-conditional-parentheses warning in
  _LIBUNWIND_ARM_EHABI libunwind builds

  ```
  src/UnwindCursor.hpp:1344:51: error: operator '?:' has lower precedence than '|'; '|' will be evaluated first [-Werror,-Wbitwise-conditional-parentheses]
    _info.flags = isSingleWordEHT ? 1 : 0 | scope32 ? 0x2 : 0;  // Use enum?
					~~~~~~~~~~~ ^
  src/UnwindCursor.hpp:1344:51: note: place parentheses around the '|' expression to silence this warning
    _info.flags = isSingleWordEHT ? 1 : 0 | scope32 ? 0x2 : 0;  // Use enum?
						    ^
					(          )
  src/UnwindCursor.hpp:1344:51: note: place parentheses around the '?:' expression to evaluate it first
    _info.flags = isSingleWordEHT ? 1 : 0 | scope32 ? 0x2 : 0;  // Use enum?
						    ^
					    (                )
  ```

  But `0 |` is a no-op for either of those two interpretations, so I
  think what was meant here was

  ```
    _info.flags = (isSingleWordEHT ? 1 : 0) | (scope32 ? 0x2 : 0);  // Use enum?
  ```

  Previously, if `isSingleWordEHT` was set, bit 2 would never be set.
  Now it is. From what I can tell, the only thing that checks these
  bitmask is ProcessDescriptors in Unwind-EHABI.cpp, and that only
  cares about bit 1, so in practice this shouldn't have much of an
  effect.

  Differential Revision: https://reviews.llvm.org/D73890

This fixes the above errors when building libunwind for arm variants.
This commit is contained in:
Dimitry Andric 2020-02-15 15:03:26 +00:00
parent 13138422bc
commit 473b61d31e
1 changed files with 3 additions and 2 deletions
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5
contrib/llvm-project/libunwind/src/UnwindCursor.hpp
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@ -1353,7 +1353,8 @@ bool UnwindCursor<A, R>::getInfoFromEHABISection(
// If the high bit is set, the exception handling table entry is inline inside
// the index table entry on the second word (aka |indexDataAddr|). Otherwise,
// the table points at an offset in the exception handling table (section 5 EHABI).
// the table points at an offset in the exception handling table (section 5
// EHABI).
pint_t exceptionTableAddr;
uint32_t exceptionTableData;
bool isSingleWordEHT;
@ -1452,7 +1453,7 @@ bool UnwindCursor<A, R>::getInfoFromEHABISection(
_info.unwind_info = exceptionTableAddr;
_info.lsda = lsda;
// flags is pr_cache.additional. See EHABI #7.2 for definition of bit 0.
_info.flags = isSingleWordEHT ? 1 : 0 | scope32 ? 0x2 : 0; // Use enum?
_info.flags = (isSingleWordEHT ? 1 : 0) | (scope32 ? 0x2 : 0); // Use enum?
return true;
}