[llvm-exegesis] Generate snippet setup code.

Summary:
This ensures that the snippet always sees the same values for registers,
making measurements reproducible.
This will also allow exploring different values.

Reviewers: gchatelet

Subscribers: tschuett, llvm-commits

Differential Revision: https://reviews.llvm.org/D48542

llvm-svn: 335465

1 files changed, 15 insertions, 1 deletions

diff --git a/llvm/tools/llvm-exegesis/lib/MCInstrDescView.cpp b/llvm/tools/llvm-exegesis/lib/MCInstrDescView.cpp
index 5678fcea94d..fc0d5b327b8 100644
--- a/llvm/tools/llvm-exegesis/lib/MCInstrDescView.cpp
+++ b/llvm/tools/llvm-exegesis/lib/MCInstrDescView.cpp
@@ -99,11 +99,22 @@ llvm::MCOperand &InstructionInstance::getValueFor(const Variable &Var) {
   return VariableValues[Var.Index];
 }
 
+const llvm::MCOperand &
+InstructionInstance::getValueFor(const Variable &Var) const {
+  return VariableValues[Var.Index];
+}
+
 llvm::MCOperand &InstructionInstance::getValueFor(const Operand &Op) {
   assert(Op.VariableIndex >= 0);
   return getValueFor(Instr.Variables[Op.VariableIndex]);
 }
 
+const llvm::MCOperand &
+InstructionInstance::getValueFor(const Operand &Op) const {
+  assert(Op.VariableIndex >= 0);
+  return getValueFor(Instr.Variables[Op.VariableIndex]);
+}
+
 // forward declaration.
 static void randomize(const Instruction &Instr, const Variable &Var,
                       llvm::MCOperand &AssignedValue);
@@ -118,12 +129,15 @@ bool InstructionInstance::hasImmediateVariables() const {
   });
 }
 
-llvm::MCInst InstructionInstance::randomizeUnsetVariablesAndBuild() {
+void InstructionInstance::randomizeUnsetVariables() {
   for (const Variable &Var : Instr.Variables) {
     llvm::MCOperand &AssignedValue = getValueFor(Var);
     if (!AssignedValue.isValid())
       randomize(Instr, Var, AssignedValue);
   }
+}
+
+llvm::MCInst InstructionInstance::build() const {
   llvm::MCInst Result;
   Result.setOpcode(Instr.Description->Opcode);
   for (const auto &Op : Instr.Operands)