[Debugify] Support checking Machine IR debug info

Add mir-check-debug pass to check MIR-level debug info.

For IR-level, currently, LLVM have debugify + check-debugify to generate
and check debug IR. Much like the IR-level pass debugify, mir-debugify
inserts sequentially increasing line locations to each MachineInstr in a
Module, But there is no equivalent MIR-level check-debugify pass, So now
we support it at "mir-check-debug".

Reviewed By: djtodoro

Differential Revision: https://reviews.llvm.org/D95195

1 files changed, 126 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/MachineCheckDebugify.cpp b/llvm/lib/CodeGen/MachineCheckDebugify.cpp
new file mode 100644
index 0000000..bd7f0f8
--- /dev/null
+++ b/llvm/lib/CodeGen/MachineCheckDebugify.cpp
@@ -0,0 +1,126 @@
+//===- MachineCheckDebugify.cpp - Check debug info ------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file This checks debug info after mir-debugify (+ pass-to-test). Currently
+/// it simply checks the integrity of line info in DILocation and
+/// DILocalVariable which mir-debugifiy generated before.
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/IR/DebugInfo.h"
+#include "llvm/InitializePasses.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Transforms/Utils/Debugify.h"
+
+#define DEBUG_TYPE "mir-check-debugify"
+
+using namespace llvm;
+
+namespace {
+
+struct CheckDebugMachineModule : public ModulePass {
+  bool runOnModule(Module &M) override {
+    MachineModuleInfo &MMI =
+        getAnalysis<MachineModuleInfoWrapperPass>().getMMI();
+
+    NamedMDNode *NMD = M.getNamedMetadata("llvm.mir.debugify");
+    if (!NMD) {
+      errs() << "WARNING: Please run mir-debugify to generate "
+                "llvm.mir.debugify metadata first.\n";
+      return false;
+    }
+
+    auto getDebugifyOperand = [&](unsigned Idx) -> unsigned {
+      return mdconst::extract<ConstantInt>(NMD->getOperand(Idx)->getOperand(0))
+          ->getZExtValue();
+    };
+    assert(NMD->getNumOperands() == 2 &&
+           "llvm.mir.debugify should have exactly 2 operands!");
+    unsigned NumLines = getDebugifyOperand(0);
+    unsigned NumVars = getDebugifyOperand(1);
+    BitVector MissingLines{NumLines, true};
+    BitVector MissingVars{NumVars, true};
+
+    for (Function &F : M.functions()) {
+      MachineFunction *MF = MMI.getMachineFunction(F);
+      if (!MF)
+        continue;
+      for (MachineBasicBlock &MBB : *MF) {
+        // Find missing lines.
+        // TODO: Avoid meta instructions other than dbg_val.
+        for (MachineInstr &MI : MBB) {
+          if (MI.isDebugValue())
+            continue;
+          const DebugLoc DL = MI.getDebugLoc();
+          if (DL && DL.getLine() != 0) {
+            MissingLines.reset(DL.getLine() - 1);
+            continue;
+          }
+
+          if (!DL) {
+            errs() << "WARNING: Instruction with empty DebugLoc in function ";
+            errs() << F.getName() << " --";
+            MI.print(errs());
+          }
+        }
+
+        // Find missing variables.
+        // TODO: Handle DBG_INSTR_REF which is under an experimental option now.
+        for (MachineInstr &MI : MBB) {
+          if (!MI.isDebugValue())
+            continue;
+          const DILocalVariable *LocalVar = MI.getDebugVariable();
+          unsigned Var = ~0U;
+
+          (void)to_integer(LocalVar->getName(), Var, 10);
+          assert(Var <= NumVars && "Unexpected name for DILocalVariable");
+          MissingVars.reset(Var - 1);
+        }
+      }
+    }
+
+    bool Fail = false;
+    for (unsigned Idx : MissingLines.set_bits()) {
+      errs() << "WARNING: Missing line " << Idx + 1 << "\n";
+      Fail = true;
+    }
+
+    for (unsigned Idx : MissingVars.set_bits()) {
+      errs() << "WARNING: Missing variable " << Idx + 1 << "\n";
+      Fail = true;
+    }
+    errs() << "Machine IR debug info check: ";
+    errs() << (Fail ? "FAIL" : "PASS") << "\n";
+
+    return false;
+  }
+
+  CheckDebugMachineModule() : ModulePass(ID) {}
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.addRequired<MachineModuleInfoWrapperPass>();
+    AU.addPreserved<MachineModuleInfoWrapperPass>();
+    AU.setPreservesCFG();
+  }
+
+  static char ID; // Pass identification.
+};
+char CheckDebugMachineModule::ID = 0;
+
+} // end anonymous namespace
+
+INITIALIZE_PASS_BEGIN(CheckDebugMachineModule, DEBUG_TYPE,
+                      "Machine Check Debug Module", false, false)
+INITIALIZE_PASS_END(CheckDebugMachineModule, DEBUG_TYPE,
+                    "Machine Check Debug Module", false, false)
+
+ModulePass *llvm::createCheckDebugMachineModulePass() {
+  return new CheckDebugMachineModule();
+}