vendor/llvm/llvm-trunk-r154661

1 files changed, 184 insertions, 0 deletions

diff --git a/lib/Analysis/CodeMetrics.cpp b/lib/Analysis/CodeMetrics.cpp
new file mode 100644
index 000000000000..316e7bc9349a
--- /dev/null
+++ b/lib/Analysis/CodeMetrics.cpp
@@ -0,0 +1,184 @@
+//===- CodeMetrics.cpp - Code cost measurements ---------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements code cost measurement utilities.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/CodeMetrics.h"
+#include "llvm/Function.h"
+#include "llvm/Support/CallSite.h"
+#include "llvm/IntrinsicInst.h"
+#include "llvm/Target/TargetData.h"
+
+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(const Function *F) {
+  if (!F) return false;
+
+  if (F->hasLocalLinkage()) return false;
+
+  if (!F->hasName()) return false;
+
+  StringRef Name = F->getName();
+
+  // 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;
+
+  // 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;
+
+  return false;
+}
+
+bool llvm::isInstructionFree(const Instruction *I, const TargetData *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;
+    }
+  }
+
+  if (const CastInst *CI = dyn_cast<CastInst>(I)) {
+    // Noop casts, including ptr <-> int,  don't count.
+    if (CI->isLosslessCast() || isa<IntToPtrInst>(CI) || isa<PtrToIntInst>(CI))
+      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;
+  }
+
+  return false;
+}
+
+/// analyzeBasicBlock - Fill in the current structure with information gleaned
+/// from the specified block.
+void CodeMetrics::analyzeBasicBlock(const BasicBlock *BB,
+                                    const TargetData *TD) {
+  ++NumBlocks;
+  unsigned NumInstsBeforeThisBB = NumInsts;
+  for (BasicBlock::const_iterator II = BB->begin(), E = BB->end();
+       II != E; ++II) {
+    if (isInstructionFree(II, TD))
+      continue;
+
+    // Special handling for calls.
+    if (isa<CallInst>(II) || isa<InvokeInst>(II)) {
+      ImmutableCallSite CS(cast<Instruction>(II));
+
+      if (const Function *F = CS.getCalledFunction()) {
+        // 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).
+        if (!CS.isNoInline() && F->hasInternalLinkage() && F->hasOneUse())
+          ++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 (!isa<IntrinsicInst>(II) && !callIsSmall(CS.getCalledFunction())) {
+        // Each argument to a call takes on average one instruction to set up.
+        NumInsts += CS.arg_size();
+
+        // 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()))
+          ++NumCalls;
+      }
+    }
+
+    if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
+      if (!AI->isStaticAlloca())
+        this->usesDynamicAlloca = true;
+    }
+
+    if (isa<ExtractElementInst>(II) || II->getType()->isVectorTy())
+      ++NumVectorInsts;
+
+    ++NumInsts;
+  }
+
+  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.
+  if (isa<IndirectBrInst>(BB->getTerminator()))
+    containsIndirectBr = true;
+
+  // Remember NumInsts for this BB.
+  NumBBInsts[BB] = NumInsts - NumInstsBeforeThisBB;
+}
+
+void CodeMetrics::analyzeFunction(Function *F, const TargetData *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->hasFnAttr(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);
+}