Imported Upstream version 6.0.0.172

Former-commit-id: f3cc9b82f3e5bd8f0fd3ebc098f789556b44e9cd

external/llvm/lib/Target/AMDGPU/SIDebuggerInsertNops.cpp

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+//===--- SIDebuggerInsertNops.cpp - Inserts nops for debugger usage -------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+/// \file
+/// \brief Inserts one nop instruction for each high level source statement for
+/// debugger usage.
+///
+/// Tools, such as a debugger, need to pause execution based on user input (i.e.
+/// breakpoint). In order to do this, one nop instruction is inserted before the
+/// first isa instruction of each high level source statement. Further, the
+/// debugger may replace nop instructions with trap instructions based on user
+/// input.
+//
+//===----------------------------------------------------------------------===//
+
+#include "AMDGPUSubtarget.h"
+#include "SIInstrInfo.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "si-debugger-insert-nops"
+#define PASS_NAME "SI Debugger Insert Nops"
+
+namespace {
+
+class SIDebuggerInsertNops : public MachineFunctionPass {
+public:
+  static char ID;
+
+  SIDebuggerInsertNops() : MachineFunctionPass(ID) { }
+  StringRef getPassName() const override { return PASS_NAME; }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.setPreservesCFG();
+    MachineFunctionPass::getAnalysisUsage(AU);
+  }
+
+  bool runOnMachineFunction(MachineFunction &MF) override;
+};
+
+} // anonymous namespace
+
+INITIALIZE_PASS(SIDebuggerInsertNops, DEBUG_TYPE, PASS_NAME, false, false)
+
+char SIDebuggerInsertNops::ID = 0;
+char &llvm::SIDebuggerInsertNopsID = SIDebuggerInsertNops::ID;
+
+FunctionPass *llvm::createSIDebuggerInsertNopsPass() {
+  return new SIDebuggerInsertNops();
+}
+
+bool SIDebuggerInsertNops::runOnMachineFunction(MachineFunction &MF) {
+  // Skip this pass if "amdgpu-debugger-insert-nops" attribute was not
+  // specified.
+  const SISubtarget &ST = MF.getSubtarget<SISubtarget>();
+  if (!ST.debuggerInsertNops())
+    return false;
+
+  // Skip machine functions without debug info.
+  if (!MF.getMMI().hasDebugInfo())
+    return false;
+
+  // Target instruction info.
+  const SIInstrInfo *TII = ST.getInstrInfo();
+
+  // Set containing line numbers that have nop inserted.
+  DenseSet<unsigned> NopInserted;
+
+  for (auto &MBB : MF) {
+    for (auto MI = MBB.begin(); MI != MBB.end(); ++MI) {
+      // Skip DBG_VALUE instructions and instructions without location.
+      if (MI->isDebugValue() || !MI->getDebugLoc())
+        continue;
+
+      // Insert nop instruction if line number does not have nop inserted.
+      auto DL = MI->getDebugLoc();
+      if (NopInserted.find(DL.getLine()) == NopInserted.end()) {
+        BuildMI(MBB, *MI, DL, TII->get(AMDGPU::S_NOP))
+          .addImm(0);
+        NopInserted.insert(DL.getLine());
+      }
+    }
+  }
+
+  return true;
+}