Pull the implementation of the code metrics out of the inline cost

analysis implementation. The header was already separated. Also cleanup
all the comments in the header to follow a nice modern doxygen form.

There is still plenty of cruft here, but some of that will fall out in
subsequent refactorings and this was an easy step in the right
direction. No functionality changed here.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@152898 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 176 insertions, 0 deletions

diff --git a/lib/Analysis/CodeMetrics.cpp b/lib/Analysis/CodeMetrics.cpp
new file mode 100644
index 0000000000..6c93f78629
--- /dev/null
+++ b/lib/Analysis/CodeMetrics.cpp
@@ -0,0 +1,176 @@
+//===- 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;
+}
+
+/// 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 (isa<PHINode>(II)) continue;           // PHI nodes don't count.
+
+    // Special handling for calls.
+    if (isa<CallInst>(II) || isa<InvokeInst>(II)) {
+      if (const IntrinsicInst *IntrinsicI = dyn_cast<IntrinsicInst>(II)) {
+        switch (IntrinsicI->getIntrinsicID()) {
+        default: break;
+        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.
+          continue;
+        }
+      }
+
+      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;
+
+    if (const CastInst *CI = dyn_cast<CastInst>(II)) {
+      // Noop casts, including ptr <-> int,  don't count.
+      if (CI->isLosslessCast() || isa<IntToPtrInst>(CI) ||
+          isa<PtrToIntInst>(CI))
+        continue;
+      // trunc to a native type is free (assuming the target has compare and
+      // shift-right of the same width).
+      if (isa<TruncInst>(CI) && TD &&
+          TD->isLegalInteger(TD->getTypeSizeInBits(CI->getType())))
+        continue;
+      // 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)))
+        continue;
+    } else if (const GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(II)){
+      // If a GEP has all constant indices, it will probably be folded with
+      // a load/store.
+      if (GEPI->hasAllConstantIndices())
+        continue;
+    }
+
+    ++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);
+}