vendor/llvm/llvm-trunk-r351319

1 files changed, 94 insertions, 0 deletions

diff --git a/lib/MCA/Support.cpp b/lib/MCA/Support.cpp
new file mode 100644
index 000000000000..335953e10481
--- /dev/null
+++ b/lib/MCA/Support.cpp
@@ -0,0 +1,94 @@
+//===--------------------- Support.cpp --------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+/// \file
+///
+/// This file implements a few helper functions used by various pipeline
+/// components.
+///
+//===----------------------------------------------------------------------===//
+
+#include "llvm/MCA/Support.h"
+#include "llvm/MC/MCSchedule.h"
+
+namespace llvm {
+namespace mca {
+
+#define DEBUG_TYPE "llvm-mca"
+
+void computeProcResourceMasks(const MCSchedModel &SM,
+                              MutableArrayRef<uint64_t> Masks) {
+  unsigned ProcResourceID = 0;
+
+  assert(Masks.size() == SM.getNumProcResourceKinds() &&
+         "Invalid number of elements");
+  // Resource at index 0 is the 'InvalidUnit'. Set an invalid mask for it.
+  Masks[0] = 0;
+
+  // Create a unique bitmask for every processor resource unit.
+  for (unsigned I = 1, E = SM.getNumProcResourceKinds(); I < E; ++I) {
+    const MCProcResourceDesc &Desc = *SM.getProcResource(I);
+    if (Desc.SubUnitsIdxBegin)
+      continue;
+    Masks[I] = 1ULL << ProcResourceID;
+    ProcResourceID++;
+  }
+
+  // Create a unique bitmask for every processor resource group.
+  for (unsigned I = 1, E = SM.getNumProcResourceKinds(); I < E; ++I) {
+    const MCProcResourceDesc &Desc = *SM.getProcResource(I);
+    if (!Desc.SubUnitsIdxBegin)
+      continue;
+    Masks[I] = 1ULL << ProcResourceID;
+    for (unsigned U = 0; U < Desc.NumUnits; ++U) {
+      uint64_t OtherMask = Masks[Desc.SubUnitsIdxBegin[U]];
+      Masks[I] |= OtherMask;
+    }
+    ProcResourceID++;
+  }
+
+#ifndef NDEBUG
+  LLVM_DEBUG(dbgs() << "\nProcessor resource masks:"
+                    << "\n");
+  for (unsigned I = 0, E = SM.getNumProcResourceKinds(); I < E; ++I) {
+    const MCProcResourceDesc &Desc = *SM.getProcResource(I);
+    LLVM_DEBUG(dbgs() << '[' << I << "] " << Desc.Name << " - " << Masks[I]
+                      << '\n');
+  }
+#endif
+}
+
+double computeBlockRThroughput(const MCSchedModel &SM, unsigned DispatchWidth,
+                               unsigned NumMicroOps,
+                               ArrayRef<unsigned> ProcResourceUsage) {
+  // The block throughput is bounded from above by the hardware dispatch
+  // throughput. That is because the DispatchWidth is an upper bound on the
+  // number of opcodes that can be part of a single dispatch group.
+  double Max = static_cast<double>(NumMicroOps) / DispatchWidth;
+
+  // The block throughput is also limited by the amount of hardware parallelism.
+  // The number of available resource units affects the resource pressure
+  // distribution, as well as how many blocks can be executed every cycle.
+  for (unsigned I = 0, E = SM.getNumProcResourceKinds(); I < E; ++I) {
+    unsigned ResourceCycles = ProcResourceUsage[I];
+    if (!ResourceCycles)
+      continue;
+
+    const MCProcResourceDesc &MCDesc = *SM.getProcResource(I);
+    double Throughput = static_cast<double>(ResourceCycles) / MCDesc.NumUnits;
+    Max = std::max(Max, Throughput);
+  }
+
+  // The block reciprocal throughput is computed as the MAX of:
+  //  - (NumMicroOps / DispatchWidth)
+  //  - (NumUnits / ResourceCycles)   for every consumed processor resource.
+  return Max;
+}
+
+} // namespace mca
+} // namespace llvm