[llvm-exegesis][NFC] Split BenchmarkRunner class
Summary:
The snippet-generation part goes to the SnippetGenerator class.
This will allow benchmarking arbitrary code (see PR38437).
Reviewers: gchatelet
Subscribers: mgorny, tschuett, llvm-commits
Differential Revision: https://reviews.llvm.org/D51979
llvm-svn: 342117
diff --git a/llvm/tools/llvm-exegesis/lib/SnippetGenerator.cpp b/llvm/tools/llvm-exegesis/lib/SnippetGenerator.cpp
new file mode 100644
index 0000000..5b51a09
--- /dev/null
+++ b/llvm/tools/llvm-exegesis/lib/SnippetGenerator.cpp
@@ -0,0 +1,130 @@
+//===-- SnippetGenerator.cpp ------------------------------------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include <array>
+#include <string>
+
+#include "Assembler.h"
+#include "MCInstrDescView.h"
+#include "SnippetGenerator.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/Twine.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/FormatVariadic.h"
+#include "llvm/Support/Program.h"
+
+namespace exegesis {
+
+SnippetGeneratorFailure::SnippetGeneratorFailure(const llvm::Twine &S)
+ : llvm::StringError(S, llvm::inconvertibleErrorCode()) {}
+
+SnippetGenerator::SnippetGenerator(const LLVMState &State)
+ : State(State), RATC(State.getRegInfo(),
+ getFunctionReservedRegs(State.getTargetMachine())) {}
+
+SnippetGenerator::~SnippetGenerator() = default;
+
+llvm::Expected<std::vector<BenchmarkCode>>
+SnippetGenerator::generateConfigurations(unsigned Opcode) const {
+ if (auto E = generateCodeTemplate(Opcode)) {
+ CodeTemplate &CT = E.get();
+ std::vector<BenchmarkCode> Output;
+ // TODO: Generate as many BenchmarkCode as needed.
+ {
+ BenchmarkCode BC;
+ BC.Info = CT.Info;
+ for (InstructionBuilder &IB : CT.Instructions) {
+ IB.randomizeUnsetVariables(
+ CT.ScratchSpacePointerInReg
+ ? RATC.getRegister(CT.ScratchSpacePointerInReg).aliasedBits()
+ : RATC.emptyRegisters());
+ BC.Instructions.push_back(IB.build());
+ }
+ if (CT.ScratchSpacePointerInReg)
+ BC.LiveIns.push_back(CT.ScratchSpacePointerInReg);
+ BC.RegsToDef = computeRegsToDef(CT.Instructions);
+ Output.push_back(std::move(BC));
+ }
+ return Output;
+ } else
+ return E.takeError();
+}
+
+std::vector<unsigned> SnippetGenerator::computeRegsToDef(
+ const std::vector<InstructionBuilder> &Instructions) const {
+ // Collect all register uses and create an assignment for each of them.
+ // Ignore memory operands which are handled separately.
+ // Loop invariant: DefinedRegs[i] is true iif it has been set at least once
+ // before the current instruction.
+ llvm::BitVector DefinedRegs = RATC.emptyRegisters();
+ std::vector<unsigned> RegsToDef;
+ for (const InstructionBuilder &IB : Instructions) {
+ // Returns the register that this Operand sets or uses, or 0 if this is not
+ // a register.
+ const auto GetOpReg = [&IB](const Operand &Op) -> unsigned {
+ if (Op.IsMem)
+ return 0;
+ if (Op.ImplicitReg)
+ return *Op.ImplicitReg;
+ if (Op.IsExplicit && IB.getValueFor(Op).isReg())
+ return IB.getValueFor(Op).getReg();
+ return 0;
+ };
+ // Collect used registers that have never been def'ed.
+ for (const Operand &Op : IB.Instr.Operands) {
+ if (!Op.IsDef) {
+ const unsigned Reg = GetOpReg(Op);
+ if (Reg > 0 && !DefinedRegs.test(Reg)) {
+ RegsToDef.push_back(Reg);
+ DefinedRegs.set(Reg);
+ }
+ }
+ }
+ // Mark defs as having been def'ed.
+ for (const Operand &Op : IB.Instr.Operands) {
+ if (Op.IsDef) {
+ const unsigned Reg = GetOpReg(Op);
+ if (Reg > 0)
+ DefinedRegs.set(Reg);
+ }
+ }
+ }
+ return RegsToDef;
+}
+
+llvm::Expected<CodeTemplate> SnippetGenerator::generateSelfAliasingCodeTemplate(
+ const Instruction &Instr) const {
+ const AliasingConfigurations SelfAliasing(Instr, Instr);
+ if (SelfAliasing.empty()) {
+ return llvm::make_error<SnippetGeneratorFailure>("empty self aliasing");
+ }
+ CodeTemplate CT;
+ InstructionBuilder IB(Instr);
+ if (SelfAliasing.hasImplicitAliasing()) {
+ CT.Info = "implicit Self cycles, picking random values.";
+ } else {
+ CT.Info = "explicit self cycles, selecting one aliasing Conf.";
+ // This is a self aliasing instruction so defs and uses are from the same
+ // instance, hence twice IB in the following call.
+ setRandomAliasing(SelfAliasing, IB, IB);
+ }
+ CT.Instructions.push_back(std::move(IB));
+ return std::move(CT);
+}
+
+llvm::Expected<CodeTemplate>
+SnippetGenerator::generateUnconstrainedCodeTemplate(const Instruction &Instr,
+ llvm::StringRef Msg) const {
+ CodeTemplate CT;
+ CT.Info = llvm::formatv("{0}, repeating an unconstrained assignment", Msg);
+ CT.Instructions.emplace_back(Instr);
+ return std::move(CT);
+}
+} // namespace exegesis