Kostin Artem. Lab #3. Var 1. (#119)

An optimization pass that replaces multiplication and addition operation with muladd instruction.

Author: aartyomm

llvm/lib/Target/X86/lab3/kostin_artem/CMakeLists.txt

@@ -0,0 +1,12 @@
+set(PluginName X86KostinPass)
+file(GLOB_RECURSE ALL_SOURCE_FILES *.cpp *.h)
+add_llvm_pass_plugin(${PluginName}
+        ${ALL_SOURCE_FILES}
+        DEPENDS
+        intrinsics_gen
+        X86
+        BUILDTREE_ONLY)
+
+target_include_directories(${PluginName} PUBLIC ${PATH_TO_X86})
+
+set(LLVM_TEST_DEPENDS ${PluginName} ${LLVM_TEST_DEPENDS} PARENT_SCOPE)

llvm/lib/Target/X86/lab3/kostin_artem/X86KostinPass.cpp

@@ -0,0 +1,84 @@
+#include "X86.h"
+#include "X86InstrInfo.h"
+#include "X86Subtarget.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include <utility>
+#include <vector>
+
+using namespace llvm;
+
+namespace {
+class X86KostinPass : public MachineFunctionPass {
+public:
+  static char ID;
+  X86KostinPass() : MachineFunctionPass(ID) {}
+  bool runOnMachineFunction(MachineFunction &MF) override;
+};
+
+char X86KostinPass::ID = 0;
+
+bool X86KostinPass::runOnMachineFunction(MachineFunction &pFunction) {
+  const TargetInstrInfo *instrInfo = pFunction.getSubtarget().getInstrInfo();
+  bool isModified = false;
+  bool isOp = false;
+  std::vector<std::pair<MachineInstr *, MachineInstr *>> toDelete;
+
+  for (auto &basicBlock : pFunction) {
+    MachineInstr *mulInstruction = nullptr;
+    MachineInstr *addInstruction = nullptr;
+    isOp = false;
+
+    for (auto &instr : basicBlock) {
+      if (instr.getOpcode() == X86::MULPDrr) {
+        mulInstruction = &instr;
+
+        for (auto next = std::next(instr.getIterator());
+             next != basicBlock.end(); ++next) {
+          if (next->getOpcode() == X86::ADDPDrr) {
+            addInstruction = &*next;
+            if (mulInstruction->getOperand(0).getReg() ==
+                    addInstruction->getOperand(2).getReg() ||
+                mulInstruction->getOperand(0).getReg() ==
+                    addInstruction->getOperand(1).getReg()) {
+              toDelete.emplace_back(mulInstruction, addInstruction);
+              isModified = true;
+              if (mulInstruction->getOperand(0).getReg() ==
+                  addInstruction->getOperand(2).getReg()) {
+                isOp = true;
+              } else {
+                isOp = false;
+              }
+              break;
+            }
+          } else if (next->definesRegister(
+                         mulInstruction->getOperand(0).getReg())) {
+            break;
+          }
+        }
+      }
+    }
+  }
+
+  for (const auto &[mulInstr, addInstr] : toDelete) {
+    MachineInstrBuilder builder =
+        BuildMI(*mulInstr->getParent(), *mulInstr, mulInstr->getDebugLoc(),
+                instrInfo->get(X86::VFMADD213PDZ128r));
+    builder.addReg(addInstr->getOperand(0).getReg(), RegState::Define);
+    builder.addReg(mulInstr->getOperand(1).getReg());
+    builder.addReg(mulInstr->getOperand(2).getReg());
+    if (isOp) {
+      builder.addReg(addInstr->getOperand(1).getReg());
+    } else {
+      builder.addReg(addInstr->getOperand(2).getReg());
+    }
+    mulInstr->eraseFromParent();
+    addInstr->eraseFromParent();
+  }
+
+  return isModified;
+}
+} // namespace
+
+static RegisterPass<X86KostinPass> X("x86-kostin-pass", "X86 Kostin Pass",
+                                     false, false);