YIELD is ARM's equivalent of x86's PAUSE, available since ARMv6k, which should be old enough that we can use it unconditionally. The ARM manual[1] defines the __yield() intrinsic for this, however: - Clang has __builtin_arm_yield, the naming is compatible with what GCC would use, so we use that if available, to avoid having to include even more headers. - GCC (incl. 12) doesn't have __yield() in arm_acle.h or anywhere else, and it doesn't seem to have the builtin (yet, one can always hope), so we use asm() there. - Windows doesn't have an arm_acle.h header, but the docs[2] say it should have __yield(). Unfortunately, the docs don't say where the intrinsic is hiding, but we already include <intrin.h>, and godbolt[3] confirms that's sufficient to use __yield(). We could use YieldProcessor(), but we'd need to include qt_windows.h, I guess, which I'd rather not. - Integrity doesn't have the arm_acle.h header, we use asm(), here, too. [1] https://developer.arm.com/documentation/dui0472/k/Compiler-specific-Features/--yield-intrinsic [2] https://docs.microsoft.com/en-us/cpp/intrinsics/arm-intrinsics?view=msvc-140 [3] https://godbolt.org/z/Evfe79xhE Pick-to: 6.3 Fixes: QTBUG-103011 Change-Id: Ibf496dfe9949f9a3d24c0dcf75a703c5fdbbb4b8 Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org> Reviewed-by: Sona Kurazyan <sona.kurazyan@qt.io> Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>