From 415b2fbef514989d665c40ca4d258e28526deedf Mon Sep 17 00:00:00 2001
From: Guillaume Chatelet <gchatelet@google.com>
Date: Mon, 1 Oct 2018 12:19:10 +0000
Subject: [llvm-exegesis][NFC] Move random functions from CodeTemplate to
 SnippetGenerator.

Summary: Just moving methods around.

Reviewers: courbet

Subscribers: tschuett, llvm-commits

Differential Revision: https://reviews.llvm.org/D52720

llvm-svn: 343461
---
 llvm/tools/llvm-exegesis/lib/SnippetGenerator.cpp | 85 +++++++++++++++++++++++
 1 file changed, 85 insertions(+)

(limited to 'llvm/tools/llvm-exegesis/lib/SnippetGenerator.cpp')

diff --git a/llvm/tools/llvm-exegesis/lib/SnippetGenerator.cpp b/llvm/tools/llvm-exegesis/lib/SnippetGenerator.cpp
index de57bf3fd70..531844cf8c9 100644
--- a/llvm/tools/llvm-exegesis/lib/SnippetGenerator.cpp
+++ b/llvm/tools/llvm-exegesis/lib/SnippetGenerator.cpp
@@ -129,4 +129,89 @@ SnippetGenerator::generateUnconstrainedCodeTemplate(const Instruction &Instr,
   return std::move(CT);
 }
 
+std::mt19937 &randomGenerator() {
+  static std::random_device RandomDevice;
+  static std::mt19937 RandomGenerator(RandomDevice());
+  return RandomGenerator;
+}
+
+static size_t randomIndex(size_t Size) {
+  assert(Size > 0);
+  std::uniform_int_distribution<> Distribution(0, Size - 1);
+  return Distribution(randomGenerator());
+}
+
+template <typename C>
+static auto randomElement(const C &Container) -> decltype(Container[0]) {
+  return Container[randomIndex(Container.size())];
+}
+
+static void randomize(const Instruction &Instr, const Variable &Var,
+                      llvm::MCOperand &AssignedValue,
+                      const llvm::BitVector &ForbiddenRegs) {
+  assert(!Var.TiedOperands.empty());
+  const Operand &Op = Instr.Operands[Var.TiedOperands.front()];
+  assert(Op.Info != nullptr);
+  const auto &OpInfo = *Op.Info;
+  switch (OpInfo.OperandType) {
+  case llvm::MCOI::OperandType::OPERAND_IMMEDIATE:
+    // FIXME: explore immediate values too.
+    AssignedValue = llvm::MCOperand::createImm(1);
+    break;
+  case llvm::MCOI::OperandType::OPERAND_REGISTER: {
+    assert(Op.Tracker);
+    auto AllowedRegs = Op.Tracker->sourceBits();
+    assert(AllowedRegs.size() == ForbiddenRegs.size());
+    for (auto I : ForbiddenRegs.set_bits())
+      AllowedRegs.reset(I);
+    AssignedValue = llvm::MCOperand::createReg(randomBit(AllowedRegs));
+    break;
+  }
+  default:
+    break;
+  }
+}
+
+static void setRegisterOperandValue(const RegisterOperandAssignment &ROV,
+                                    InstructionTemplate &IB) {
+  assert(ROV.Op);
+  if (ROV.Op->IsExplicit) {
+    auto &AssignedValue = IB.getValueFor(*ROV.Op);
+    if (AssignedValue.isValid()) {
+      assert(AssignedValue.isReg() && AssignedValue.getReg() == ROV.Reg);
+      return;
+    }
+    AssignedValue = llvm::MCOperand::createReg(ROV.Reg);
+  } else {
+    assert(ROV.Op->ImplicitReg != nullptr);
+    assert(ROV.Reg == *ROV.Op->ImplicitReg);
+  }
+}
+
+size_t randomBit(const llvm::BitVector &Vector) {
+  assert(Vector.any());
+  auto Itr = Vector.set_bits_begin();
+  for (size_t I = randomIndex(Vector.count()); I != 0; --I)
+    ++Itr;
+  return *Itr;
+}
+
+void setRandomAliasing(const AliasingConfigurations &AliasingConfigurations,
+                       InstructionTemplate &DefIB, InstructionTemplate &UseIB) {
+  assert(!AliasingConfigurations.empty());
+  assert(!AliasingConfigurations.hasImplicitAliasing());
+  const auto &RandomConf = randomElement(AliasingConfigurations.Configurations);
+  setRegisterOperandValue(randomElement(RandomConf.Defs), DefIB);
+  setRegisterOperandValue(randomElement(RandomConf.Uses), UseIB);
+}
+
+void randomizeUnsetVariables(const llvm::BitVector &ForbiddenRegs,
+                             InstructionTemplate &IT) {
+  for (const Variable &Var : IT.Instr.Variables) {
+    llvm::MCOperand &AssignedValue = IT.getValueFor(Var);
+    if (!AssignedValue.isValid())
+      randomize(IT.Instr, Var, AssignedValue, ForbiddenRegs);
+  }
+}
+
 } // namespace exegesis
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