[llvm] [KernelInfo] Implement new LLVM IR pass for GPU code analysis (PR #102944)

[Joel E. Denny via llvm-commits]

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+//===- KernelInfo.cpp - Kernel Analysis -----------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the KernelInfo, KernelInfoAnalysis, and KernelInfoPrinter
+// classes used to extract function properties from a kernel.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/KernelInfo.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/Analysis/OptimizationRemarkEmitter.h"
+#include "llvm/IR/DebugInfo.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Metadata.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/PassManager.h"
+#include "llvm/Passes/PassBuilder.h"
+
+using namespace llvm;
+
+#define DEBUG_TYPE "kernel-info"
+
+static bool isKernelFunction(Function &F) {
+  // TODO: Is this general enough?  Consider languages beyond OpenMP.
+  return F.hasFnAttribute("kernel");
+}
+
+static void identifyFunction(OptimizationRemark &R, const Function &F) {
+  if (auto *SubProgram = F.getSubprogram()) {
+    if (SubProgram->isArtificial())
+      R << "artificial ";
+  }
+  R << "function '" << F.getName() << "'";
+}
+
+static void remarkAlloca(OptimizationRemarkEmitter &ORE, const Function &Caller,
+                         const AllocaInst &Alloca,
+                         TypeSize::ScalarTy StaticSize) {
+  ORE.emit([&] {
+    StringRef Name;
+    DebugLoc Loc;
+    bool Artificial = false;
+    auto DVRs = findDVRDeclares(&const_cast<AllocaInst &>(Alloca));
+    if (!DVRs.empty()) {
+      const DbgVariableRecord &DVR = **DVRs.begin();
+      Name = DVR.getVariable()->getName();
+      Loc = DVR.getDebugLoc();
+      Artificial = DVR.Variable->isArtificial();
+    }
+    OptimizationRemark R(DEBUG_TYPE, "Alloca", DiagnosticLocation(Loc),
+                         Alloca.getParent());
+    R << "in ";
+    identifyFunction(R, Caller);
+    R << ", ";
+    if (Artificial)
+      R << "artificial ";
+    if (Name.empty()) {
+      R << "unnamed alloca ";
+      if (DVRs.empty())
+        R << "(missing debug metadata) ";
+    } else {
+      R << "alloca '" << Name << "' ";
+    }
+    R << "with ";
+    if (StaticSize)
+      R << "static size of " << itostr(StaticSize) << " bytes";
+    else
+      R << "dynamic size";
+    return R;
+  });
+}
+
+static void remarkCall(OptimizationRemarkEmitter &ORE, const Function &Caller,
+                       const CallBase &Call, StringRef CallKind,
+                       StringRef RemarkKind) {
+  ORE.emit([&] {
+    OptimizationRemark R(DEBUG_TYPE, RemarkKind, &Call);
+    R << "in ";
+    identifyFunction(R, Caller);
+    R << ", " << CallKind;
+    if (const Function *Callee =
+            dyn_cast_or_null<Function>(Call.getCalledOperand())) {
+      R << ", callee is";
+      StringRef Name = Callee->getName();
+      if (auto *SubProgram = Callee->getSubprogram()) {
+        if (SubProgram->isArtificial())
+          R << " artificial";
+      }
+      if (!Name.empty())
+        R << " '" << Name << "'";
+      else
+        R << " with unknown name";
+    }
+    return R;
+  });
+}
+
+static void remarkFlatAddrspaceAccess(OptimizationRemarkEmitter &ORE,
+                                      const Function &Caller,
+                                      const Instruction &Inst) {
+  ORE.emit([&] {
+    OptimizationRemark R(DEBUG_TYPE, "FlatAddrspaceAccess", &Inst);
+    R << "in ";
+    identifyFunction(R, Caller);
+    if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(&Inst)) {
+      R << ", '" << II->getCalledFunction()->getName() << "' call";
+    } else {
+      R << ", '" << Inst.getOpcodeName() << "' instruction";
+    }
+    if (Inst.hasName())
+      R << " ('%" << Inst.getName() << "')";
+    R << " accesses memory in flat address space";
+    return R;
+  });
+}
+
+void KernelInfo::updateForBB(const BasicBlock &BB, int64_t Direction,
+                             OptimizationRemarkEmitter &ORE) {
+  assert(Direction == 1 || Direction == -1);
+  const Function &F = *BB.getParent();
+  const Module &M = *F.getParent();
+  const DataLayout &DL = M.getDataLayout();
+  for (const Instruction &I : BB.instructionsWithoutDebug()) {
+    if (const AllocaInst *Alloca = dyn_cast<AllocaInst>(&I)) {
+      Allocas += Direction;
+      TypeSize::ScalarTy StaticSize = 0;
+      if (std::optional<TypeSize> Size = Alloca->getAllocationSize(DL)) {
+        StaticSize = Size->getFixedValue();
+        assert(StaticSize <= std::numeric_limits<int64_t>::max());
+        AllocasStaticSizeSum += Direction * StaticSize;
+      } else {
+        AllocasDyn += Direction;
+      }
+      remarkAlloca(ORE, F, *Alloca, StaticSize);
+    } else if (const CallBase *Call = dyn_cast<CallBase>(&I)) {
+      SmallString<40> CallKind;
+      SmallString<40> RemarkKind;
+      if (Call->isIndirectCall()) {
+        IndirectCalls += Direction;
+        CallKind += "indirect";
+        RemarkKind += "Indirect";
+      } else {
+        DirectCalls += Direction;
+        CallKind += "direct";
+        RemarkKind += "Direct";
+      }
+      if (isa<InvokeInst>(Call)) {
+        Invokes += Direction;
+        CallKind += " invoke";
+        RemarkKind += "Invoke";
+      } else {
+        CallKind += " call";
+        RemarkKind += "Call";
+      }
+      if (!Call->isIndirectCall()) {
+        if (const Function *Callee = Call->getCalledFunction()) {
+          if (Callee && !Callee->isIntrinsic() && !Callee->isDeclaration()) {
----------------
jdenny-ornl wrote:

Done.

https://github.com/llvm/llvm-project/pull/102944