[llvm-exegesis][mips] Add support for memory instructions

Implementing functions used to enable testing of memory instructions.

Differential Revision: https://reviews.llvm.org/D72858

Author: Miloš Stojanović

llvm/tools/llvm-exegesis/lib/Mips/Target.cpp

@@ -7,12 +7,44 @@
 //===----------------------------------------------------------------------===//
 #include "../Target.h"
 #include "../Latency.h"
+#include "MCTargetDesc/MipsBaseInfo.h"
 #include "Mips.h"
 #include "MipsRegisterInfo.h"
 
 namespace llvm {
 namespace exegesis {
 
+// Returns an error if we cannot handle the memory references in this
+// instruction.
+static Error isInvalidMemoryInstr(const Instruction &Instr) {
+  switch (Instr.Description.TSFlags & MipsII::FormMask) {
+  default:
+    return Error::success();
+    llvm_unreachable("Unknown FormMask value");
+  // These have no memory access.
+  case MipsII::Pseudo:
+  case MipsII::FrmR:
+  case MipsII::FrmJ:
+  case MipsII::FrmFR:
+    return Error::success();
+  // These access memory and are handled.
+  case MipsII::FrmI:
+    return Error::success();
+  // These access memory and are not handled yet.
+  case MipsII::FrmFI:
+  case MipsII::FrmOther:
+    return make_error<Failure>("unsupported opcode: non uniform memory access");
+  }
+}
+
+// Helper to fill a memory operand with a value.
+static void setMemOp(InstructionTemplate &IT, int OpIdx,
+                     const MCOperand &OpVal) {
+  const auto Op = IT.getInstr().Operands[OpIdx];
+  assert(Op.isExplicit() && "invalid memory pattern");
+  IT.getValueFor(Op) = OpVal;
+}
+
 #include "MipsGenExegesis.inc"
 
 namespace {
@@ -21,6 +53,11 @@ class ExegesisMipsTarget : public ExegesisTarget {
   ExegesisMipsTarget() : ExegesisTarget(MipsCpuPfmCounters) {}
 
 private:
+  unsigned getScratchMemoryRegister(const llvm::Triple &TT) const override;
+  unsigned getMaxMemoryAccessSize() const override { return 64; }
+  void fillMemoryOperands(InstructionTemplate &IT, unsigned Reg,
+                          unsigned Offset) const override;
+
   std::vector<MCInst> setRegTo(const MCSubtargetInfo &STI, unsigned Reg,
                                const APInt &Value) const override;
   bool matchesArch(Triple::ArchType Arch) const override {
@@ -92,6 +129,20 @@ static std::vector<MCInst> loadImmediate(unsigned Reg, bool IsGPR32,
   llvm_unreachable("Not implemented for values wider than 32 bits");
 }
 
+unsigned ExegesisMipsTarget::getScratchMemoryRegister(const Triple &TT) const {
+  return TT.isArch64Bit() ? Mips::A0_64 : Mips::A0;
+}
+
+void ExegesisMipsTarget::fillMemoryOperands(InstructionTemplate &IT,
+                                            unsigned Reg,
+                                            unsigned Offset) const {
+  assert(!isInvalidMemoryInstr(IT.getInstr()) &&
+         "fillMemoryOperands requires a valid memory instruction");
+  setMemOp(IT, 0, MCOperand::createReg(0));      // IndexReg
+  setMemOp(IT, 1, MCOperand::createReg(Reg));    // BaseReg
+  setMemOp(IT, 2, MCOperand::createImm(Offset)); // Disp
+}
+
 std::vector<MCInst> ExegesisMipsTarget::setRegTo(const MCSubtargetInfo &STI,
                                                  unsigned Reg,
                                                  const APInt &Value) const {

llvm/unittests/tools/llvm-exegesis/Mips/SnippetGeneratorTest.cpp

@@ -13,6 +13,7 @@
 #include "MipsInstrInfo.h"
 #include "RegisterAliasing.h"
 #include "TestBase.h"
+#include "Uops.h"
 
 #include <unordered_set>
 
@@ -22,6 +23,7 @@ namespace {
 
 using testing::AnyOf;
 using testing::ElementsAre;
+using testing::HasSubstr;
 using testing::SizeIs;
 
 MATCHER(IsInvalid, "") { return !arg.isValid(); }
@@ -49,6 +51,8 @@ class SnippetGeneratorTest : public MipsSnippetGeneratorTest {
 using LatencySnippetGeneratorTest =
     SnippetGeneratorTest<LatencySnippetGenerator>;
 
+using UopsSnippetGeneratorTest = SnippetGeneratorTest<UopsSnippetGenerator>;
+
 TEST_F(LatencySnippetGeneratorTest, ImplicitSelfDependencyThroughExplicitRegs) {
   // - ADD
   // - Op0 Explicit Def RegClass(GPR32)
@@ -57,6 +61,7 @@ TEST_F(LatencySnippetGeneratorTest, ImplicitSelfDependencyThroughExplicitRegs) {
   // - Var0 [Op0]
   // - Var1 [Op1]
   // - Var2 [Op2]
+  // - hasAliasingRegisters
   const unsigned Opcode = Mips::ADD;
   const auto CodeTemplates = checkAndGetCodeTemplates(Opcode);
   ASSERT_THAT(CodeTemplates, SizeIs(1));
@@ -81,6 +86,7 @@ TEST_F(LatencySnippetGeneratorTest,
   // - Var0 [Op0]
   // - Var1 [Op1]
   // - Var2 [Op2]
+  // - hasAliasingRegisters
   randomGenerator().seed(0); // Initialize seed.
   const Instruction &Instr = State.getIC().getInstr(Mips::XOR);
   auto AllRegisters = State.getRATC().emptyRegisters();
@@ -90,6 +96,31 @@ TEST_F(LatencySnippetGeneratorTest,
   consumeError(std::move(Error));
 }
 
+TEST_F(UopsSnippetGeneratorTest, MemoryUse) {
+  // LB reads from memory.
+  // - LB
+  // - Op0 Explicit Def RegClass(GPR32)
+  // - Op1 Explicit Use Memory RegClass(MSA128F16)
+  // - Op2 Explicit Use Memory
+  // - Var0 [Op0]
+  // - Var1 [Op1]
+  // - Var2 [Op2]
+  // - hasMemoryOperands
+  const unsigned Opcode = Mips::LB;
+  const auto CodeTemplates = checkAndGetCodeTemplates(Opcode);
+  ASSERT_THAT(CodeTemplates, SizeIs(1));
+  const auto &CT = CodeTemplates[0];
+  EXPECT_THAT(CT.Info, HasSubstr("instruction is parallel, repeating a random one."));
+  EXPECT_THAT(CT.Execution, ExecutionMode::UNKNOWN);
+  ASSERT_THAT(CT.Instructions,
+              SizeIs(UopsSnippetGenerator::kMinNumDifferentAddresses));
+  const InstructionTemplate &IT = CT.Instructions[0];
+  EXPECT_THAT(IT.getOpcode(), Opcode);
+  ASSERT_THAT(IT.getVariableValues(), SizeIs(3));
+  EXPECT_EQ(IT.getVariableValues()[0].getReg(), 0u);
+  EXPECT_EQ(IT.getVariableValues()[2].getImm(), 0);
+}
+
 } // namespace
 } // namespace exegesis
 } // namespace llvm