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Diffstat (limited to 'contrib/llvm/lib/Analysis/CodeMetrics.cpp')
-rw-r--r-- | contrib/llvm/lib/Analysis/CodeMetrics.cpp | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Analysis/CodeMetrics.cpp b/contrib/llvm/lib/Analysis/CodeMetrics.cpp new file mode 100644 index 0000000..316e7bc9 --- /dev/null +++ b/contrib/llvm/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); +} |