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Simplify RALinScan::DowngradeRegister with TRI::getOverlaps while we are there. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122940 91177308-0d34-0410-b5e6-96231b3b80d8
161 lines
5.4 KiB
C++
161 lines
5.4 KiB
C++
//===- SimplifyHalfPowrLibCalls.cpp - Optimize specific half_powr calls ---===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements a simple pass that applies an experimental
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// transformation on calls to specific functions.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "simplify-libcalls-halfpowr"
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Instructions.h"
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#include "llvm/Intrinsics.h"
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#include "llvm/Module.h"
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#include "llvm/Pass.h"
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#include "llvm/Transforms/Utils/BasicBlockUtils.h"
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#include "llvm/Transforms/Utils/Cloning.h"
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#include "llvm/Target/TargetData.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/Support/Debug.h"
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using namespace llvm;
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namespace {
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/// This pass optimizes well half_powr function calls.
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///
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class SimplifyHalfPowrLibCalls : public FunctionPass {
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const TargetData *TD;
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public:
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static char ID; // Pass identification
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SimplifyHalfPowrLibCalls() : FunctionPass(ID) {
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initializeSimplifyHalfPowrLibCallsPass(*PassRegistry::getPassRegistry());
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}
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bool runOnFunction(Function &F);
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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}
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Instruction *
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InlineHalfPowrs(const std::vector<Instruction *> &HalfPowrs,
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Instruction *InsertPt);
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};
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char SimplifyHalfPowrLibCalls::ID = 0;
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} // end anonymous namespace.
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INITIALIZE_PASS(SimplifyHalfPowrLibCalls, "simplify-libcalls-halfpowr",
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"Simplify half_powr library calls", false, false)
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// Public interface to the Simplify HalfPowr LibCalls pass.
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FunctionPass *llvm::createSimplifyHalfPowrLibCallsPass() {
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return new SimplifyHalfPowrLibCalls();
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}
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/// InlineHalfPowrs - Inline a sequence of adjacent half_powr calls, rearranging
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/// their control flow to better facilitate subsequent optimization.
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Instruction *
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SimplifyHalfPowrLibCalls::
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InlineHalfPowrs(const std::vector<Instruction *> &HalfPowrs,
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Instruction *InsertPt) {
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std::vector<BasicBlock *> Bodies;
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BasicBlock *NewBlock = 0;
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for (unsigned i = 0, e = HalfPowrs.size(); i != e; ++i) {
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CallInst *Call = cast<CallInst>(HalfPowrs[i]);
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Function *Callee = Call->getCalledFunction();
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// Minimally sanity-check the CFG of half_powr to ensure that it contains
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// the kind of code we expect. If we're running this pass, we have
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// reason to believe it will be what we expect.
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Function::iterator I = Callee->begin();
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BasicBlock *Prologue = I++;
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if (I == Callee->end()) break;
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BasicBlock *SubnormalHandling = I++;
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if (I == Callee->end()) break;
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BasicBlock *Body = I++;
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if (I != Callee->end()) break;
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if (SubnormalHandling->getSinglePredecessor() != Prologue)
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break;
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BranchInst *PBI = dyn_cast<BranchInst>(Prologue->getTerminator());
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if (!PBI || !PBI->isConditional())
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break;
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BranchInst *SNBI = dyn_cast<BranchInst>(SubnormalHandling->getTerminator());
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if (!SNBI || SNBI->isConditional())
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break;
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if (!isa<ReturnInst>(Body->getTerminator()))
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break;
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Instruction *NextInst = llvm::next(BasicBlock::iterator(Call));
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// Inline the call, taking care of what code ends up where.
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NewBlock = SplitBlock(NextInst->getParent(), NextInst, this);
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InlineFunctionInfo IFI(0, TD);
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bool B = InlineFunction(Call, IFI);
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assert(B && "half_powr didn't inline?");
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(void)B;
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BasicBlock *NewBody = NewBlock->getSinglePredecessor();
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assert(NewBody);
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Bodies.push_back(NewBody);
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}
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if (!NewBlock)
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return InsertPt;
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// Put the code for all the bodies into one block, to facilitate
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// subsequent optimization.
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(void)SplitEdge(NewBlock->getSinglePredecessor(), NewBlock, this);
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for (unsigned i = 0, e = Bodies.size(); i != e; ++i) {
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BasicBlock *Body = Bodies[i];
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Instruction *FNP = Body->getFirstNonPHI();
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// Splice the insts from body into NewBlock.
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NewBlock->getInstList().splice(NewBlock->begin(), Body->getInstList(),
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FNP, Body->getTerminator());
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}
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return NewBlock->begin();
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}
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/// runOnFunction - Top level algorithm.
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///
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bool SimplifyHalfPowrLibCalls::runOnFunction(Function &F) {
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TD = getAnalysisIfAvailable<TargetData>();
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bool Changed = false;
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std::vector<Instruction *> HalfPowrs;
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for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
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for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
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// Look for calls.
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bool IsHalfPowr = false;
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if (CallInst *CI = dyn_cast<CallInst>(I)) {
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// Look for direct calls and calls to non-external functions.
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Function *Callee = CI->getCalledFunction();
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if (Callee && Callee->hasExternalLinkage()) {
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// Look for calls with well-known names.
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if (Callee->getName() == "__half_powrf4")
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IsHalfPowr = true;
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}
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}
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if (IsHalfPowr)
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HalfPowrs.push_back(I);
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// We're looking for sequences of up to three such calls, which we'll
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// simplify as a group.
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if ((!IsHalfPowr && !HalfPowrs.empty()) || HalfPowrs.size() == 3) {
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I = InlineHalfPowrs(HalfPowrs, I);
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E = I->getParent()->end();
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HalfPowrs.clear();
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Changed = true;
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}
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}
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assert(HalfPowrs.empty() && "Block had no terminator!");
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}
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return Changed;
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}
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