//
//===----------------------------------------------------------------------===//
+#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/CodeMetrics.h"
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/IR/CallSite.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IntrinsicInst.h"
-#include "llvm/Support/CallSite.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+
+#define DEBUG_TYPE "code-metrics"
using namespace llvm;
-/// callIsSmall - If a call is likely to lower to a single target instruction,
-/// or is otherwise deemed small return true.
-/// TODO: Perhaps calls like memcpy, strcpy, etc?
-bool llvm::callIsSmall(ImmutableCallSite CS) {
- if (isa<IntrinsicInst>(CS.getInstruction()))
- return true;
+static void completeEphemeralValues(SmallVector<const Value *, 16> &WorkSet,
+ SmallPtrSetImpl<const Value*> &EphValues) {
+ SmallPtrSet<const Value *, 32> Visited;
- const Function *F = CS.getCalledFunction();
- if (!F) return false;
+ // Make sure that all of the items in WorkSet are in our EphValues set.
+ EphValues.insert(WorkSet.begin(), WorkSet.end());
- if (F->hasLocalLinkage()) return false;
+ // Note: We don't speculate PHIs here, so we'll miss instruction chains kept
+ // alive only by ephemeral values.
- if (!F->hasName()) return false;
+ while (!WorkSet.empty()) {
+ const Value *V = WorkSet.front();
+ WorkSet.erase(WorkSet.begin());
- StringRef Name = F->getName();
+ if (!Visited.insert(V).second)
+ continue;
- // These will all likely lower to a single selection DAG node.
- if (Name == "copysign" || Name == "copysignf" || Name == "copysignl" ||
- Name == "fabs" || Name == "fabsf" || Name == "fabsl" ||
- Name == "sin" || Name == "sinf" || Name == "sinl" ||
- Name == "cos" || Name == "cosf" || Name == "cosl" ||
- Name == "sqrt" || Name == "sqrtf" || Name == "sqrtl" )
- return true;
+ // If all uses of this value are ephemeral, then so is this value.
+ if (!std::all_of(V->user_begin(), V->user_end(),
+ [&](const User *U) { return EphValues.count(U); }))
+ continue;
- // These are all likely to be optimized into something smaller.
- if (Name == "pow" || Name == "powf" || Name == "powl" ||
- Name == "exp2" || Name == "exp2l" || Name == "exp2f" ||
- Name == "floor" || Name == "floorf" || Name == "ceil" ||
- Name == "round" || Name == "ffs" || Name == "ffsl" ||
- Name == "abs" || Name == "labs" || Name == "llabs")
- return true;
+ EphValues.insert(V);
+ DEBUG(dbgs() << "Ephemeral Value: " << *V << "\n");
- return false;
+ if (const User *U = dyn_cast<User>(V))
+ for (const Value *J : U->operands()) {
+ if (isSafeToSpeculativelyExecute(J))
+ WorkSet.push_back(J);
+ }
+ }
}
-bool llvm::isInstructionFree(const Instruction *I, const DataLayout *TD) {
- if (isa<PHINode>(I))
- return true;
-
- // If a GEP has all constant indices, it will probably be folded with
- // a load/store.
- if (const GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(I))
- return GEP->hasAllConstantIndices();
-
- if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
- switch (II->getIntrinsicID()) {
- default:
- return false;
- case Intrinsic::dbg_declare:
- case Intrinsic::dbg_value:
- case Intrinsic::invariant_start:
- case Intrinsic::invariant_end:
- case Intrinsic::lifetime_start:
- case Intrinsic::lifetime_end:
- case Intrinsic::objectsize:
- case Intrinsic::ptr_annotation:
- case Intrinsic::var_annotation:
- // These intrinsics don't count as size.
- return true;
- }
+// Find all ephemeral values.
+void CodeMetrics::collectEphemeralValues(
+ const Loop *L, AssumptionCache *AC,
+ SmallPtrSetImpl<const Value *> &EphValues) {
+ SmallVector<const Value *, 16> WorkSet;
+
+ 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 to 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;
+
+ WorkSet.push_back(I);
}
- if (const CastInst *CI = dyn_cast<CastInst>(I)) {
- // Noop casts, including ptr <-> int, don't count.
- if (CI->isLosslessCast())
- return true;
-
- Value *Op = CI->getOperand(0);
- // An inttoptr cast is free so long as the input is a legal integer type
- // which doesn't contain values outside the range of a pointer.
- if (isa<IntToPtrInst>(CI) && TD &&
- TD->isLegalInteger(Op->getType()->getScalarSizeInBits()) &&
- Op->getType()->getScalarSizeInBits() <= TD->getPointerSizeInBits())
- return true;
-
- // A ptrtoint cast is free so long as the result is large enough to store
- // the pointer, and a legal integer type.
- if (isa<PtrToIntInst>(CI) && TD &&
- TD->isLegalInteger(Op->getType()->getScalarSizeInBits()) &&
- Op->getType()->getScalarSizeInBits() >= TD->getPointerSizeInBits())
- return true;
-
- // trunc to a native type is free (assuming the target has compare and
- // shift-right of the same width).
- if (TD && isa<TruncInst>(CI) &&
- TD->isLegalInteger(TD->getTypeSizeInBits(CI->getType())))
- return true;
- // Result of a cmp instruction is often extended (to be used by other
- // cmp instructions, logical or return instructions). These are usually
- // nop on most sane targets.
- if (isa<CmpInst>(CI->getOperand(0)))
- return true;
+ completeEphemeralValues(WorkSet, EphValues);
+}
+
+void CodeMetrics::collectEphemeralValues(
+ const Function *F, AssumptionCache *AC,
+ SmallPtrSetImpl<const Value *> &EphValues) {
+ SmallVector<const Value *, 16> WorkSet;
+
+ for (auto &AssumeVH : AC->assumptions()) {
+ if (!AssumeVH)
+ continue;
+ Instruction *I = cast<Instruction>(AssumeVH);
+ assert(I->getParent()->getParent() == F &&
+ "Found assumption for the wrong function!");
+ WorkSet.push_back(I);
}
- return false;
+ completeEphemeralValues(WorkSet, EphValues);
}
/// analyzeBasicBlock - Fill in the current structure with information gleaned
/// from the specified block.
void CodeMetrics::analyzeBasicBlock(const BasicBlock *BB,
- const DataLayout *TD) {
+ const TargetTransformInfo &TTI,
+ SmallPtrSetImpl<const Value*> &EphValues) {
++NumBlocks;
unsigned NumInstsBeforeThisBB = NumInsts;
for (BasicBlock::const_iterator II = BB->begin(), E = BB->end();
II != E; ++II) {
- if (isInstructionFree(II, TD))
+ // Skip ephemeral values.
+ if (EphValues.count(&*II))
continue;
// Special handling for calls.
// for that case.
if (F == BB->getParent())
isRecursive = true;
- }
-
- if (!callIsSmall(CS)) {
- // Each argument to a call takes on average one instruction to set up.
- NumInsts += CS.arg_size();
+ if (TTI.isLoweredToCall(F))
+ ++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 (!isa<InlineAsm>(CS.getCalledValue()))
if (isa<ExtractElementInst>(II) || II->getType()->isVectorTy())
++NumVectorInsts;
+ if (II->getType()->isTokenTy() && II->isUsedOutsideOfBlock(BB))
+ notDuplicatable = true;
+
if (const CallInst *CI = dyn_cast<CallInst>(II))
- if (CI->hasFnAttr(Attribute::NoDuplicate))
+ if (CI->cannotDuplicate())
notDuplicatable = true;
if (const InvokeInst *InvI = dyn_cast<InvokeInst>(II))
- if (InvI->hasFnAttr(Attribute::NoDuplicate))
+ if (InvI->cannotDuplicate())
notDuplicatable = true;
- ++NumInsts;
+ NumInsts += TTI.getUserCost(&*II);
}
if (isa<ReturnInst>(BB->getTerminator()))
// Remember NumInsts for this BB.
NumBBInsts[BB] = NumInsts - NumInstsBeforeThisBB;
}
-
-void CodeMetrics::analyzeFunction(Function *F, const DataLayout *TD) {
- // If this function contains a call that "returns twice" (e.g., setjmp or
- // _setjmp) and it isn't marked with "returns twice" itself, never inline it.
- // This is a hack because we depend on the user marking their local variables
- // as volatile if they are live across a setjmp call, and they probably
- // won't do this in callers.
- exposesReturnsTwice = F->callsFunctionThatReturnsTwice() &&
- !F->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
- Attribute::ReturnsTwice);
-
- // Look at the size of the callee.
- for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
- analyzeBasicBlock(&*BB, TD);
-}
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