[llvm] r366868 - [RISCV] Implement benchmark::cycleclock::Now

[Roger Ferrer Ibanez via llvm-commits]

Author: rogfer01
Date: Tue Jul 23 22:33:46 2019
New Revision: 366868

URL: http://llvm.org/viewvc/llvm-project?rev=366868&view=rev
Log:
[RISCV] Implement benchmark::cycleclock::Now

This is a cherrypick of D64237 onto llvm/utils/benchmark and
libcxx/utils/google-benchmark.

Differential Revision: https://reviews.llvm.org/D65142

Modified:
    llvm/trunk/utils/benchmark/README.LLVM
    llvm/trunk/utils/benchmark/src/cycleclock.h

Modified: llvm/trunk/utils/benchmark/README.LLVM
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/utils/benchmark/README.LLVM?rev=366868&r1=366867&r2=366868&view=diff
==============================================================================
--- llvm/trunk/utils/benchmark/README.LLVM (original)
+++ llvm/trunk/utils/benchmark/README.LLVM Tue Jul 23 22:33:46 2019
@@ -23,3 +23,5 @@ Changes:
   is applied to disable exceptions in Microsoft STL when exceptions are disabled
 * Disabled CMake get_git_version as it is meaningless for this in-tree build,
   and hardcoded a null version
+* https://github.com/google/benchmark/commit/4abdfbb802d1b514703223f5f852ce4a507d32d2
+  is applied on top of v1.4.1 to add RISC-V timer support.

Modified: llvm/trunk/utils/benchmark/src/cycleclock.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/utils/benchmark/src/cycleclock.h?rev=366868&r1=366867&r2=366868&view=diff
==============================================================================
--- llvm/trunk/utils/benchmark/src/cycleclock.h (original)
+++ llvm/trunk/utils/benchmark/src/cycleclock.h Tue Jul 23 22:33:46 2019
@@ -164,6 +164,21 @@ inline BENCHMARK_ALWAYS_INLINE int64_t N
   uint64_t tsc;
   asm("stck %0" : "=Q" (tsc) : : "cc");
   return tsc;
+#elif defined(__riscv) // RISC-V
+  // Use RDCYCLE (and RDCYCLEH on riscv32)
+#if __riscv_xlen == 32
+  uint64_t cycles_low, cycles_hi0, cycles_hi1;
+  asm("rdcycleh %0" : "=r"(cycles_hi0));
+  asm("rdcycle %0" : "=r"(cycles_lo));
+  asm("rdcycleh %0" : "=r"(cycles_hi1));
+  // This matches the PowerPC overflow detection, above
+  cycles_lo &= -static_cast<int64_t>(cycles_hi0 == cycles_hi1);
+  return (cycles_hi1 << 32) | cycles_lo;
+#else
+  uint64_t cycles;
+  asm("rdcycle %0" : "=r"(cycles));
+  return cycles;
+#endif
 #else
 // The soft failover to a generic implementation is automatic only for ARM.
 // For other platforms the developer is expected to make an attempt to create