1 files changed, 202 insertions, 0 deletions
diff --git a/contrib/llvm-project/llvm/lib/Analysis/CodeMetrics.cpp b/contrib/llvm-project/llvm/lib/Analysis/CodeMetrics.cpp
new file mode 100644
index 000000000000..2637e2f97dbb
--- /dev/null
+++ b/contrib/llvm-project/llvm/lib/Analysis/CodeMetrics.cpp
@@ -0,0 +1,202 @@
+//===- CodeMetrics.cpp - Code cost measurements ---------------------------===//
+//
+// 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 implements code cost measurement utilities.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/CodeMetrics.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/Analysis/AssumptionCache.h"
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/IR/Function.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/InstructionCost.h"
+
+#define DEBUG_TYPE "code-metrics"
+
+using namespace llvm;
+
+static void
+appendSpeculatableOperands(const Value *V,
+                           SmallPtrSetImpl<const Value *> &Visited,
+                           SmallVectorImpl<const Value *> &Worklist) {
+  const User *U = dyn_cast<User>(V);
+  if (!U)
+    return;
+
+  for (const Value *Operand : U->operands())
+    if (Visited.insert(Operand).second)
+      if (const auto *I = dyn_cast<Instruction>(Operand))
+        if (!I->mayHaveSideEffects() && !I->isTerminator())
+          Worklist.push_back(I);
+}
+
+static void completeEphemeralValues(SmallPtrSetImpl<const Value *> &Visited,
+                                    SmallVectorImpl<const Value *> &Worklist,
+                                    SmallPtrSetImpl<const Value *> &EphValues) {
+  // Note: We don't speculate PHIs here, so we'll miss instruction chains kept
+  // alive only by ephemeral values.
+
+  // Walk the worklist using an index but without caching the size so we can
+  // append more entries as we process the worklist. This forms a queue without
+  // quadratic behavior by just leaving processed nodes at the head of the
+  // worklist forever.
+  for (int i = 0; i < (int)Worklist.size(); ++i) {
+    const Value *V = Worklist[i];
+
+    assert(Visited.count(V) &&
+           "Failed to add a worklist entry to our visited set!");
+
+    // If all uses of this value are ephemeral, then so is this value.
+    if (!all_of(V->users(), [&](const User *U) { return EphValues.count(U); }))
+      continue;
+
+    EphValues.insert(V);
+    LLVM_DEBUG(dbgs() << "Ephemeral Value: " << *V << "\n");
+
+    // Append any more operands to consider.
+    appendSpeculatableOperands(V, Visited, Worklist);
+  }
+}
+
+// Find all ephemeral values.
+void CodeMetrics::collectEphemeralValues(
+    const Loop *L, AssumptionCache *AC,
+    SmallPtrSetImpl<const Value *> &EphValues) {
+  SmallPtrSet<const Value *, 32> Visited;
+  SmallVector<const Value *, 16> Worklist;
+
+  for (auto &AssumeVH : AC->assumptions()) {
+    if (!AssumeVH)
+      continue;
+    Instruction *I = cast<Instruction>(AssumeVH);
+
+    // Filter out call sites outside of the loop so we don't do a function's
+    // worth of work for each of its loops (and, in the common case, ephemeral
+    // values in the loop are likely due to @llvm.assume calls in the loop).
+    if (!L->contains(I->getParent()))
+      continue;
+
+    if (EphValues.insert(I).second)
+      appendSpeculatableOperands(I, Visited, Worklist);
+  }
+
+  completeEphemeralValues(Visited, Worklist, EphValues);
+}
+
+void CodeMetrics::collectEphemeralValues(
+    const Function *F, AssumptionCache *AC,
+    SmallPtrSetImpl<const Value *> &EphValues) {
+  SmallPtrSet<const Value *, 32> Visited;
+  SmallVector<const Value *, 16> Worklist;
+
+  for (auto &AssumeVH : AC->assumptions()) {
+    if (!AssumeVH)
+      continue;
+    Instruction *I = cast<Instruction>(AssumeVH);
+    assert(I->getParent()->getParent() == F &&
+           "Found assumption for the wrong function!");
+
+    if (EphValues.insert(I).second)
+      appendSpeculatableOperands(I, Visited, Worklist);
+  }
+
+  completeEphemeralValues(Visited, Worklist, EphValues);
+}
+
+/// Fill in the current structure with information gleaned from the specified
+/// block.
+void CodeMetrics::analyzeBasicBlock(
+    const BasicBlock *BB, const TargetTransformInfo &TTI,
+    const SmallPtrSetImpl<const Value *> &EphValues, bool PrepareForLTO) {
+  ++NumBlocks;
+  InstructionCost NumInstsBeforeThisBB = NumInsts;
+  for (const Instruction &I : *BB) {
+    // Skip ephemeral values.
+    if (EphValues.count(&I))
+      continue;
+
+    // Special handling for calls.
+    if (const auto *Call = dyn_cast<CallBase>(&I)) {
+      if (const Function *F = Call->getCalledFunction()) {
+        bool IsLoweredToCall = TTI.isLoweredToCall(F);
+        // If a function is both internal and has a single use, then it is
+        // extremely likely to get inlined in the future (it was probably
+        // exposed by an interleaved devirtualization pass).
+        // When preparing for LTO, liberally consider calls as inline
+        // candidates.
+        if (!Call->isNoInline() && IsLoweredToCall &&
+            ((F->hasInternalLinkage() && F->hasOneLiveUse()) ||
+             PrepareForLTO)) {
+          ++NumInlineCandidates;
+        }
+
+        // If this call is to function itself, then the function is recursive.
+        // Inlining it into other functions is a bad idea, because this is
+        // basically just a form of loop peeling, and our metrics aren't useful
+        // for that case.
+        if (F == BB->getParent())
+          isRecursive = true;
+
+        if (IsLoweredToCall)
+          ++NumCalls;
+      } else {
+        // We don't want inline asm to count as a call - that would prevent loop
+        // unrolling. The argument setup cost is still real, though.
+        if (!Call->isInlineAsm())
+          ++NumCalls;
+      }
+    }
+
+    if (const AllocaInst *AI = dyn_cast<AllocaInst>(&I)) {
+      if (!AI->isStaticAlloca())
+        this->usesDynamicAlloca = true;
+    }
+
+    if (isa<ExtractElementInst>(I) || I.getType()->isVectorTy())
+      ++NumVectorInsts;
+
+    if (I.getType()->isTokenTy() && I.isUsedOutsideOfBlock(BB))
+      notDuplicatable = true;
+
+    if (const CallInst *CI = dyn_cast<CallInst>(&I)) {
+      if (CI->cannotDuplicate())
+        notDuplicatable = true;
+      if (CI->isConvergent())
+        convergent = true;
+    }
+
+    if (const InvokeInst *InvI = dyn_cast<InvokeInst>(&I))
+      if (InvI->cannotDuplicate())
+        notDuplicatable = true;
+
+    NumInsts += TTI.getInstructionCost(&I, TargetTransformInfo::TCK_CodeSize);
+  }
+
+  if (isa<ReturnInst>(BB->getTerminator()))
+    ++NumRets;
+
+  // We never want to inline functions that contain an indirectbr.  This is
+  // incorrect because all the blockaddress's (in static global initializers
+  // for example) would be referring to the original function, and this indirect
+  // jump would jump from the inlined copy of the function into the original
+  // function which is extremely undefined behavior.
+  // FIXME: This logic isn't really right; we can safely inline functions
+  // with indirectbr's as long as no other function or global references the
+  // blockaddress of a block within the current function.  And as a QOI issue,
+  // if someone is using a blockaddress without an indirectbr, and that
+  // reference somehow ends up in another function or global, we probably
+  // don't want to inline this function.
+  notDuplicatable |= isa<IndirectBrInst>(BB->getTerminator());
+
+  // Remember NumInsts for this BB.
+  InstructionCost NumInstsThisBB = NumInsts - NumInstsBeforeThisBB;
+  NumBBInsts[BB] = NumInstsThisBB;
+}