RFR: 8291649: multiple tests failing with -Xcomp after JDK-8290034

[David Schlosnagle]

On Tue, 23 Aug 2022 17:58:39 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

> Hi,
> 
> This bug fix patch fixes the incorrect computation during constant folding of Reverse[IL] IR node.
> A new utility class has been added to optimize computation of reverse_bit operation using GCC built-ins.
> 
> Kindly review and share your feedback.
> 
> Best Regards,
> Jatin

src/hotspot/share/utilities/moveBits.hpp line 31:

> 29: #include "utilities/globalDefinitions.hpp"
> 30: 
> 31: inline uint64_t bit_reverse(uint64_t x) {

Should this still credit Hacker's Delight?

Suggestion:

inline uint64_t bit_reverse(uint64_t x) {
  // Hacker's Delight, Figure 7-1

src/hotspot/share/utilities/moveBits.hpp line 47:

> 45:       x = (x & 0x00FF00FF00FF00FFL) << 8 | (x & 0xFF00FF00FF00FF00L) >> 8;
> 46:     default:
> 47:       break;

Should this assert not reachable?

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PR: https://git.openjdk.org/jdk/pull/9987