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Introduce CONSTEXPR_UNREACHABLE

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g++ versions <= 8 cannot use UNREACHABLE() in a
constexpr function. As a workaround a new macro is defined to
instead use `abort` if this feature is not properly handled by the
compiler.

Change-Id: Id6daf02b86c38daa12b7e6f42629091c9833f6fe
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3988005
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Commit-Queue: Milad Farazmand <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/main@{#83985}
This commit is contained in:
Milad Fa 2022-10-28 11:14:02 -04:00 committed by V8 LUCI CQ
parent 45427e4d77
commit 708d75cd4c
2 changed files with 9 additions and 2 deletions
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7
src/base/logging.h
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@ -48,6 +48,13 @@ V8_BASE_EXPORT V8_NOINLINE void V8_Dcheck(const char* file, int line,
#define UNIMPLEMENTED() FATAL("unimplemented code")
#define UNREACHABLE() FATAL("unreachable code")
// g++ versions <= 8 cannot use UNREACHABLE() in a constexpr function.
// TODO(miladfarca): Remove once all compilers handle this properly.
#if defined(__GNUC__) && !defined(__clang__) && (__GNUC__ <= 8)
#define CONSTEXPR_UNREACHABLE() abort()
#else
#define CONSTEXPR_UNREACHABLE() UNREACHABLE()
#endif
namespace v8 {
namespace base {

4
src/objects/elements-kind.h
View File

@ -220,9 +220,9 @@ inline constexpr int ElementsKindToShiftSize(ElementsKind elements_kind) {
return kTaggedSizeLog2;
case WASM_ARRAY_ELEMENTS:
case NO_ELEMENTS:
UNREACHABLE();
CONSTEXPR_UNREACHABLE();
}
UNREACHABLE();
CONSTEXPR_UNREACHABLE();
}
inline constexpr int ElementsKindToByteSize(ElementsKind elements_kind) {
return 1 << ElementsKindToShiftSize(elements_kind);