Borovkov Sergey. Lab 2. Option 4. (#146)

Added a plugin that changes integer multiplication by bitwise shift if at least one of the operands is power of two.
NN-complr-tech · May 20, 2024 · f36d729 · f36d729
1 parent 794c363
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diff --git a/llvm/labs/lab2/borovkov_sergey/CMakeLists.txt b/llvm/labs/lab2/borovkov_sergey/CMakeLists.txt
@@ -0,0 +1,11 @@
+if (NOT WIN32 AND NOT CYGWIN)
+  set(PluginName MulShiftsBorovkovPlugin)
+
+  file(GLOB_RECURSE ALL_SOURCE_FILES *.cpp *.h)
+  add_llvm_pass_plugin(${PluginName} 
+   ${ALL_SOURCE_FILES} DEPENDS
+    intrinsics_gen
+    BUILDTREE_ONLY )
+
+  set(LLVM_TEST_DEPENDS ${PluginName} ${LLVM_TEST_DEPENDS} PARENT_SCOPE)
+endif()
diff --git a/llvm/labs/lab2/borovkov_sergey/MulWithShift.cpp b/llvm/labs/lab2/borovkov_sergey/MulWithShift.cpp
@@ -0,0 +1,114 @@
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/Pass.h"
+#include "llvm/Passes/PassBuilder.h"
+#include "llvm/Passes/PassPlugin.h"
+#include <optional>
+
+namespace {
+struct MulShifts : llvm::PassInfoMixin<MulShifts> {
+public:
+  llvm::PreservedAnalyses run(llvm::Function &Func,
+                              llvm::FunctionAnalysisManager &FAM) {
+    std::vector<llvm::Instruction *> toRemove;
+
+    for (llvm::BasicBlock &BB : Func) {
+      for (llvm::Instruction &Inst : BB) {
+        if (!llvm::BinaryOperator::classof(&Inst)) {
+          continue;
+        }
+        llvm::BinaryOperator *op = llvm::cast<llvm::BinaryOperator>(&Inst);
+        if (op->getOpcode() != llvm::Instruction::BinaryOps::Mul) {
+          continue;
+        }
+
+        llvm::Value *lhs = op->getOperand(0);
+        llvm::Value *rhs = op->getOperand(1);
+
+        auto lg1 = getLogBase2(lhs);
+        auto lg2 = getLogBase2(rhs);
+        if (!lg1 && !lg2) {
+          continue;
+        }
+        if (lg1 < lg2) {
+          std::swap(lg1, lg2);
+          std::swap(lhs, rhs);
+        }
+
+        if (lg1) {
+          llvm::Value *lg_val = llvm::ConstantInt::get(
+              llvm::IntegerType::get(Func.getContext(), 32),
+              llvm::APInt(32, *lg1));
+
+          llvm::Value *val = llvm::BinaryOperator::Create(
+              llvm::Instruction::Shl, rhs, lg_val, op->getName(), op);
+
+          op->replaceAllUsesWith(val);
+          toRemove.push_back(op);
+        }
+      }
+      for (auto *I : toRemove) {
+        I->eraseFromParent();
+      }
+    }
+
+    auto PA = llvm::PreservedAnalyses::all();
+    return PA;
+  }
+
+private:
+  std::optional<int> getLogBase2(llvm::Value *val) {
+    if (llvm::ConstantInt *CI = llvm::dyn_cast<llvm::ConstantInt>(val)) {
+      if (CI->getValue().isPowerOf2()) {
+        return CI->getValue().exactLogBase2();
+      }
+    }
+    if (auto *LI = llvm::dyn_cast<llvm::LoadInst>(val)) {
+      llvm::Value *Op = LI->getPointerOperand();
+      Op->reverseUseList();
+      llvm::StoreInst *StInst = nullptr;
+      for (auto *Inst : Op->users()) {
+        if (auto *SI = llvm::dyn_cast<llvm::StoreInst>(Inst)) {
+          StInst = SI;
+        }
+        if (Inst == LI) {
+          break;
+        }
+      }
+      Op->reverseUseList();
+      if (!StInst) {
+        return std::nullopt;
+      }
+      if (auto *CI =
+              llvm::dyn_cast<llvm::ConstantInt>(StInst->getValueOperand())) {
+        if (CI->getValue().isPowerOf2()) {
+          return CI->getValue().exactLogBase2();
+        }
+      }
+    }
+    return std::nullopt;
+  }
+};
+} // namespace
+
+bool registerPlugin(llvm::StringRef Name, llvm::FunctionPassManager &FPM,
+                    llvm::ArrayRef<llvm::PassBuilder::PipelineElement>) {
+  if (Name == "borovkovmulshifts") {
+    FPM.addPass(MulShifts());
+    return true;
+  }
+  return false;
+}
+
+llvm::PassPluginLibraryInfo getMulShiftsBorovkovPluginInfo() {
+  return {LLVM_PLUGIN_API_VERSION, "MulShifts", LLVM_VERSION_STRING,
+          [](llvm::PassBuilder &PB) {
+            PB.registerPipelineParsingCallback(registerPlugin);
+          }};
+}
+
+extern "C" LLVM_ATTRIBUTE_WEAK llvm::PassPluginLibraryInfo
+llvmGetPassPluginInfo() {
+  return getMulShiftsBorovkovPluginInfo();
+}
diff --git a/llvm/test/lab2/borovkov_sergey/test.ll b/llvm/test/lab2/borovkov_sergey/test.ll
@@ -0,0 +1,149 @@
+; RUN: opt -load-pass-plugin=%llvmshlibdir/MulShiftsBorovkovPlugin%shlibext -passes=borovkovmulshifts -S %s | FileCheck %s
+
+;int f1(int a){
+;    int c = a + 4;
+;    return c;
+
+define dso_local i32 @f1(i32 noundef %0) #0 {
+  %2 = alloca i32, align 4
+  %3 = alloca i32, align 4
+  store i32 %0, ptr %2, align 4
+  %4 = load i32, ptr %2, align 4
+  %5 = add nsw i32 %4, 4
+  store i32 %5, ptr %3, align 4
+  %6 = load i32, ptr %3, align 4
+  ret i32 %6
+}
+
+; CHECK-LABEL: @f1
+; CHECK: %[[load:[0-9]+]] = load i32, ptr %2, align 4
+; CHECK-NEXT: %5 = add nsw i32 %[[load]], 4
+; CHECK-NEXT: store i32 %5, ptr %3, align 4
+;}
+
+
+;int f2(int a){
+;    int c = a * 4;
+;    return c;
+
+define dso_local i32 @f2(i32 noundef %0) #0 {
+  %2 = alloca i32, align 4
+  %3 = alloca i32, align 4
+  store i32 %0, ptr %2, align 4
+  %4 = load i32, ptr %2, align 4
+  %5 = mul nsw i32 %4, 4
+  store i32 %5, ptr %3, align 4
+  %6 = load i32, ptr %3, align 4
+  ret i32 %6
+}
+
+; CHECK-LABEL: @f2
+; CHECK: %[[load:[0-9]+]] = load i32, ptr %2, align 4
+; CHECK-NEXT: %5 = shl i32 %[[load]], 2
+; CHECK-NEXT: store i32 %5, ptr %3, align 4
+;}
+
+
+;void f3(){
+;    int a = 3;
+;    int c = a * 4;
+
+define dso_local void @f3() #0 {
+  %1 = alloca i32, align 4
+  %2 = alloca i32, align 4
+  store i32 3, ptr %1, align 4
+  %3 = load i32, ptr %1, align 4
+  %4 = mul nsw i32 %3, 4
+  store i32 %4, ptr %2, align 4
+  ret void
+}
+
+; CHECK-LABEL: @f3
+; CHECK: %[[load:[0-9]+]] = load i32, ptr %1, align 4
+; CHECK-NEXT: %4 = shl i32 %[[load]], 2
+; CHECK-NEXT: store i32 %4, ptr %2, align 4
+;}
+
+
+;void f4(){
+;    int a = 3;
+;    int c = 4 * a;
+
+define dso_local void @f4() #0 {
+  %1 = alloca i32, align 4
+  %2 = alloca i32, align 4
+  store i32 3, ptr %1, align 4
+  %3 = load i32, ptr %1, align 4
+  %4 = mul nsw i32 4, %3
+  store i32 %4, ptr %2, align 4
+  ret void
+}
+
+; CHECK-LABEL: @f4
+; CHECK: %[[load:[0-9]+]] = load i32, ptr %1, align 4
+; CHECK-NEXT: %4 = shl i32 %[[load]], 2
+; CHECK-NEXT: store i32 %4, ptr %2, align 4
+;}
+
+
+;void f5(){
+;    int a = 4;
+;    int c = a * 1;
+;}
+
+define dso_local void @f5() #0 {
+  %1 = alloca i32, align 4
+  %2 = alloca i32, align 4
+  store i32 4, ptr %1, align 4
+  %3 = load i32, ptr %1, align 4
+  %4 = mul nsw i32 %3, 1
+  store i32 %4, ptr %2, align 4
+  ret void
+}
+
+; CHECK-LABEL: @f5
+; CHECK: %3 = load i32, ptr %1, align 4
+; CHECK-NEXT: %4 = shl i32 1, 2
+; CHECK-NEXT: store i32 %4, ptr %2, align 4
+
+
+;void f6(){
+;    int a = 3;
+;    int c = 0 * a;
+;}
+
+define dso_local void @f6() #0 {
+  %1 = alloca i32, align 4
+  %2 = alloca i32, align 4
+  store i32 3, ptr %1, align 4
+  %3 = load i32, ptr %1, align 4
+  %4 = mul nsw i32 0, %3
+  store i32 %4, ptr %2, align 4
+  ret void
+}
+
+; CHECK-LABEL: @f6
+; CHECK: %3 = load i32, ptr %1, align 4
+; CHECK-NEXT: %4 = mul nsw i32 0, %3
+; CHECK-NEXT: store i32 %4, ptr %2, align 4
+
+
+;void f7(){
+;    int a = 4;
+;    int c = a * 3;
+;}
+
+define dso_local void @f7() #0 {
+  %1 = alloca i32, align 4
+  %2 = alloca i32, align 4
+  store i32 4, ptr %1, align 4
+  %3 = load i32, ptr %1, align 4
+  %4 = mul nsw i32 %3, 3
+  store i32 %4, ptr %2, align 4
+  ret void
+}
+
+; CHECK-LABEL: @f7
+; CHECK: %3 = load i32, ptr %1, align 4
+; CHECK-NEXT: %4 = shl i32 3, 2
+; CHECK-NEXT: store i32 %4, ptr %2, align 4