Imported Upstream version 5.18.0.246

Former-commit-id: 0c7ce5b1a7851e13f22acfd379b7f9fb304e4833

external/llvm/lib/Target/NVPTX/NVPTXAllocaHoisting.cpp

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+//===-- AllocaHoisting.cpp - Hoist allocas to the entry block --*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Hoist the alloca instructions in the non-entry blocks to the entry blocks.
+//
+//===----------------------------------------------------------------------===//
+
+#include "NVPTXAllocaHoisting.h"
+#include "llvm/CodeGen/StackProtector.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instructions.h"
+using namespace llvm;
+
+namespace {
+// Hoisting the alloca instructions in the non-entry blocks to the entry
+// block.
+class NVPTXAllocaHoisting : public FunctionPass {
+public:
+  static char ID; // Pass ID
+  NVPTXAllocaHoisting() : FunctionPass(ID) {}
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.addPreserved<StackProtector>();
+  }
+
+  StringRef getPassName() const override {
+    return "NVPTX specific alloca hoisting";
+  }
+
+  bool runOnFunction(Function &function) override;
+};
+} // namespace
+
+bool NVPTXAllocaHoisting::runOnFunction(Function &function) {
+  bool functionModified = false;
+  Function::iterator I = function.begin();
+  TerminatorInst *firstTerminatorInst = (I++)->getTerminator();
+
+  for (Function::iterator E = function.end(); I != E; ++I) {
+    for (BasicBlock::iterator BI = I->begin(), BE = I->end(); BI != BE;) {
+      AllocaInst *allocaInst = dyn_cast<AllocaInst>(BI++);
+      if (allocaInst && isa<ConstantInt>(allocaInst->getArraySize())) {
+        allocaInst->moveBefore(firstTerminatorInst);
+        functionModified = true;
+      }
+    }
+  }
+
+  return functionModified;
+}
+
+char NVPTXAllocaHoisting::ID = 0;
+
+namespace llvm {
+void initializeNVPTXAllocaHoistingPass(PassRegistry &);
+}
+
+INITIALIZE_PASS(
+    NVPTXAllocaHoisting, "alloca-hoisting",
+    "Hoisting alloca instructions in non-entry blocks to the entry block",
+    false, false)
+
+FunctionPass *llvm::createAllocaHoisting() { return new NVPTXAllocaHoisting; }