Imported Upstream version 5.18.0.205

Former-commit-id: 7f59f7e792705db773f1caecdaa823092f4e2927

external/llvm/lib/Transforms/Scalar/PartiallyInlineLibCalls.cpp

@@ -0,0 +1,180 @@
+//===--- PartiallyInlineLibCalls.cpp - Partially inline libcalls ----------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass tries to partially inline the fast path of well-known library
+// functions, such as using square-root instructions for cases where sqrt()
+// does not need to set errno.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Scalar/PartiallyInlineLibCalls.h"
+#include "llvm/Analysis/TargetLibraryInfo.h"
+#include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+
+using namespace llvm;
+
+#define DEBUG_TYPE "partially-inline-libcalls"
+
+
+static bool optimizeSQRT(CallInst *Call, Function *CalledFunc,
+                         BasicBlock &CurrBB, Function::iterator &BB,
+                         const TargetTransformInfo *TTI) {
+  // There is no need to change the IR, since backend will emit sqrt
+  // instruction if the call has already been marked read-only.
+  if (Call->onlyReadsMemory())
+    return false;
+
+  // Do the following transformation:
+  //
+  // (before)
+  // dst = sqrt(src)
+  //
+  // (after)
+  // v0 = sqrt_noreadmem(src) # native sqrt instruction.
+  // [if (v0 is a NaN) || if (src < 0)]
+  //   v1 = sqrt(src)         # library call.
+  // dst = phi(v0, v1)
+  //
+
+  // Move all instructions following Call to newly created block JoinBB.
+  // Create phi and replace all uses.
+  BasicBlock *JoinBB = llvm::SplitBlock(&CurrBB, Call->getNextNode());
+  IRBuilder<> Builder(JoinBB, JoinBB->begin());
+  Type *Ty = Call->getType();
+  PHINode *Phi = Builder.CreatePHI(Ty, 2);
+  Call->replaceAllUsesWith(Phi);
+
+  // Create basic block LibCallBB and insert a call to library function sqrt.
+  BasicBlock *LibCallBB = BasicBlock::Create(CurrBB.getContext(), "call.sqrt",
+                                             CurrBB.getParent(), JoinBB);
+  Builder.SetInsertPoint(LibCallBB);
+  Instruction *LibCall = Call->clone();
+  Builder.Insert(LibCall);
+  Builder.CreateBr(JoinBB);
+
+  // Add attribute "readnone" so that backend can use a native sqrt instruction
+  // for this call. Insert a FP compare instruction and a conditional branch
+  // at the end of CurrBB.
+  Call->addAttribute(AttributeList::FunctionIndex, Attribute::ReadNone);
+  CurrBB.getTerminator()->eraseFromParent();
+  Builder.SetInsertPoint(&CurrBB);
+  Value *FCmp = TTI->isFCmpOrdCheaperThanFCmpZero(Ty)
+                    ? Builder.CreateFCmpORD(Call, Call)
+                    : Builder.CreateFCmpOGE(Call->getOperand(0),
+                                            ConstantFP::get(Ty, 0.0));
+  Builder.CreateCondBr(FCmp, JoinBB, LibCallBB);
+
+  // Add phi operands.
+  Phi->addIncoming(Call, &CurrBB);
+  Phi->addIncoming(LibCall, LibCallBB);
+
+  BB = JoinBB->getIterator();
+  return true;
+}
+
+static bool runPartiallyInlineLibCalls(Function &F, TargetLibraryInfo *TLI,
+                                       const TargetTransformInfo *TTI) {
+  bool Changed = false;
+
+  Function::iterator CurrBB;
+  for (Function::iterator BB = F.begin(), BE = F.end(); BB != BE;) {
+    CurrBB = BB++;
+
+    for (BasicBlock::iterator II = CurrBB->begin(), IE = CurrBB->end();
+         II != IE; ++II) {
+      CallInst *Call = dyn_cast<CallInst>(&*II);
+      Function *CalledFunc;
+
+      if (!Call || !(CalledFunc = Call->getCalledFunction()))
+        continue;
+
+      if (Call->isNoBuiltin())
+        continue;
+
+      // Skip if function either has local linkage or is not a known library
+      // function.
+      LibFunc LF;
+      if (CalledFunc->hasLocalLinkage() ||
+          !TLI->getLibFunc(*CalledFunc, LF) || !TLI->has(LF))
+        continue;
+
+      switch (LF) {
+      case LibFunc_sqrtf:
+      case LibFunc_sqrt:
+        if (TTI->haveFastSqrt(Call->getType()) &&
+            optimizeSQRT(Call, CalledFunc, *CurrBB, BB, TTI))
+          break;
+        continue;
+      default:
+        continue;
+      }
+
+      Changed = true;
+      break;
+    }
+  }
+
+  return Changed;
+}
+
+PreservedAnalyses
+PartiallyInlineLibCallsPass::run(Function &F, FunctionAnalysisManager &AM) {
+  auto &TLI = AM.getResult<TargetLibraryAnalysis>(F);
+  auto &TTI = AM.getResult<TargetIRAnalysis>(F);
+  if (!runPartiallyInlineLibCalls(F, &TLI, &TTI))
+    return PreservedAnalyses::all();
+  return PreservedAnalyses::none();
+}
+
+namespace {
+class PartiallyInlineLibCallsLegacyPass : public FunctionPass {
+public:
+  static char ID;
+
+  PartiallyInlineLibCallsLegacyPass() : FunctionPass(ID) {
+    initializePartiallyInlineLibCallsLegacyPassPass(
+        *PassRegistry::getPassRegistry());
+  }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.addRequired<TargetLibraryInfoWrapperPass>();
+    AU.addRequired<TargetTransformInfoWrapperPass>();
+    FunctionPass::getAnalysisUsage(AU);
+  }
+
+  bool runOnFunction(Function &F) override {
+    if (skipFunction(F))
+      return false;
+
+    TargetLibraryInfo *TLI =
+        &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
+    const TargetTransformInfo *TTI =
+        &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
+    return runPartiallyInlineLibCalls(F, TLI, TTI);
+  }
+};
+}
+
+char PartiallyInlineLibCallsLegacyPass::ID = 0;
+INITIALIZE_PASS_BEGIN(PartiallyInlineLibCallsLegacyPass,
+                      "partially-inline-libcalls",
+                      "Partially inline calls to library functions", false,
+                      false)
+INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
+INITIALIZE_PASS_END(PartiallyInlineLibCallsLegacyPass,
+                    "partially-inline-libcalls",
+                    "Partially inline calls to library functions", false, false)
+
+FunctionPass *llvm::createPartiallyInlineLibCallsPass() {
+  return new PartiallyInlineLibCallsLegacyPass();
+}