[benchmark][PowerPC] Rename mftbl to mftb

[stevewan]

Summary

mftb and mftbl are equivalent, yet mftbl is not recognized on AIX. Therefore, rename mftbl to only have mftb.

For extra reference: Linux Kernel Mailing List reference for replacing mftbl with mftb, https://lkml.org/lkml/2020/10/1/1048.

[lebedev.ri]

Please can you submit this upstream first, so it doesn't get lost?

[stevewan]

In D89506#2334012, @lebedev.ri wrote:

Please can you submit this upstream first, so it doesn't get lost?

Upstream patch submitted at https://github.com/google/benchmark/pull/1069.
Status: Merged.

[ldionne]

Fine for libc++.

[stevewan]

Kindly ping.

[lebedev.ri]

Thanks.
Please rebase if nessesary.
Please add an entry to llvm/utils/benchmark/README.llvm and to libcxx/utils/google-benchmark/README.llvm which contains information about cherry-picked commits that are applied on top of the local copy.

[stevewan]

Add information about the cherry-picked commit and contributor.

[lebedev.ri]

Thank you, please feel free to land this.
There's another copy in test-suite, which is not in the monorepo, might be good to also update it too.

[stevewan]

Recover overwritten commits.

[stevewan]

In D89506#2374263, @lebedev.ri wrote:

Thank you, please feel free to land this.
There's another copy in test-suite, which is not in the monorepo, might be good to also update it too.

For records, link to the test-suite patch, https://reviews.llvm.org/D90779.

libcxx/utils/google-benchmark/CONTRIBUTORS

 Paul Redmond <[e-mail]>
 Pierre Phaneuf <[e-mail]>
 Radoslav Yovchev <[e-mail]>
 Raul Marin <[e-mail]>
 Ray Glover <[e-mail]>
 Robert Guo <[e-mail]>
 Roman Lebedev <[e-mail]>
 Shuo Chen <[e-mail]>
+Steven Wan <[e-mail]>
 Tobias Ulvgård <[e-mail]>
 Tom Madams <[e-mail]> <[e-mail]>
 Yixuan Qiu <[e-mail]>
 Yusuke Suzuki <[e-mail]>
 Zbigniew Skowron <[e-mail]>
 Min-Yih Hsu <[e-mail]>

libcxx/utils/google-benchmark/README.LLVM

* https://github.com/google/benchmark/commit/a77d5f70efaebe2b7e8c10134526a23a7ce7ef35
   https://github.com/google/benchmark/commit/ecc1685340f58f7fe6b707036bc0bb1fccabb0c1
   are applied on top of
   https://github.com/google/benchmark/commit/8e48105d465c586068dd8e248fe75a8971c6ba3a
   to fix timestamp-related inline asm issues and 32-bit RISC-V build failures.
   The second cherrypicked commit fixes formatting issues introduced by the
   preceding change.
 * https://github.com/google/benchmark/commit/ffe1342eb2faa7d2e7c35b4db2ccf99fab81ec20
   is applied to add the CycleTimer implementation for M680x0
+* https://github.com/google/benchmark/commit/d9abf017632be4a00b92cf4289539b353fcea5d2
+  is applied to rename 'mftbl' to 'mftb'.

libcxx/utils/google-benchmark/src/cycleclock.h

 // data might be inaccurate due to out of order instruction execution.
 // ----------------------------------------------------------------------
 
 #ifndef BENCHMARK_CYCLECLOCK_H_
 #define BENCHMARK_CYCLECLOCK_H_
 
 #include <cstdint>
 
 #include "benchmark/benchmark.h"
 #include "internal_macros.h"
 
 #if defined(BENCHMARK_OS_MACOSX)
 #include <mach/mach_time.h>
 #endif
 // For MSVC, we want to use '_asm rdtsc' when possible (since it works
 // with even ancient MSVC compilers), and when not possible the
 // __rdtsc intrinsic, declared in <intrin.h>.  Unfortunately, in some

 #if defined(__powerpc64__) || defined(__ppc64__)
   int64_t tb;
   asm volatile("mfspr %0, 268" : "=r"(tb));
   return tb;
 #else
   uint32_t tbl, tbu0, tbu1;
   asm volatile(
       "mftbu %0\n"
-      "mftbl %1\n"
+      "mftb %1\n"
       "mftbu %2"
       : "=r"(tbu0), "=r"(tbl), "=r"(tbu1));
   tbl &= -static_cast<int32_t>(tbu0 == tbu1);
   // high 32 bits in tbu1; low 32 bits in tbl  (tbu0 is no longer needed)
   return (static_cast<uint64_t>(tbu1) << 32) | tbl;
 #endif
 #elif defined(__sparc__)
   int64_t tick;

llvm/utils/benchmark/CONTRIBUTORS

 Paul Redmond <[e-mail]>
 Pierre Phaneuf <[e-mail]>
 Radoslav Yovchev <[e-mail]>
 Raul Marin <[e-mail]>
 Ray Glover <[e-mail]>
 Robert Guo <[e-mail]>
 Roman Lebedev <[e-mail]>
 Shuo Chen <[e-mail]>
+Steven Wan <[e-mail]>
 Tobias Ulvgård <[e-mail]>
 Tom Madams <[e-mail]> <[e-mail]>
 Yixuan Qiu <[e-mail]>
 Yusuke Suzuki <[e-mail]>
 Zbigniew Skowron <[e-mail]>
 Min-Yih Hsu <[e-mail]>

llvm/utils/benchmark/README.LLVM

 * https://github.com/google/benchmark/commit/a77d5f70efaebe2b7e8c10134526a23a7ce7ef35
   and
   https://github.com/google/benchmark/commit/ecc1685340f58f7fe6b707036bc0bb1fccabb0c1
   are applied on top of the previous cherrypick to fix timestamp-related inline
   asm issues and 32-bit RISC-V build failures. The second cherrypicked commit
   fixes formatting issues introduced by the preceding change.
 * https://github.com/google/benchmark/commit/ffe1342eb2faa7d2e7c35b4db2ccf99fab81ec20
   is applied to add the CycleTimer implementation for M680x0
+* https://github.com/google/benchmark/commit/d9abf017632be4a00b92cf4289539b353fcea5d2
+  is applied to rename 'mftbl' to 'mftb'.

llvm/utils/benchmark/src/cycleclock.h

 #elif defined(__powerpc__) || defined(__ppc__)
   // This returns a time-base, which is not always precisely a cycle-count.
 #if defined(__powerpc64__) || defined(__ppc64__)
   int64_t tb;
   asm volatile("mfspr %0, 268" : "=r"(tb));
   return tb;
 #else
   uint32_t tbl, tbu0, tbu1;
   asm volatile(
       "mftbu %0\n"
-      "mftbl %1\n"
+      "mftb %1\n"
       "mftbu %2"
       : "=r"(tbu0), "=r"(tbl), "=r"(tbu1));
   tbl &= -static_cast<int32_t>(tbu0 == tbu1);
   // high 32 bits in tbu1; low 32 bits in tbl  (tbu0 is no longer needed)
   return (static_cast<uint64_t>(tbu1) << 32) | tbl;
 #endif
 #elif defined(__sparc__)
   int64_t tick;