[globalisel][irtranslator] Verify that DILocations aren't lost in translation

Summary:
Also fix a couple bugs where DILocations are lost. EntryBuilder wasn't passing
on debug locations for PHI's, constants, GLOBAL_VALUE, etc.

Reviewers: aprantl, vsk, bogner, aditya_nandakumar, volkan, rtereshin, aemerson

Reviewed By: aemerson

Subscribers: aemerson, rovka, kristof.beyls, javed.absar, llvm-commits

Differential Revision: https://reviews.llvm.org/D53740

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@345743 91177308-0d34-0410-b5e6-96231b3b80d8

Author: dsandersllvm

lib/CodeGen/GlobalISel/IRTranslator.cpp

@@ -104,6 +104,36 @@ IRTranslator::IRTranslator() : MachineFunctionPass(ID) {
   initializeIRTranslatorPass(*PassRegistry::getPassRegistry());
 }
 
+#ifndef NDEBUG
+/// Verify that every instruction created has the same DILocation as the
+/// instruction being translated.
+class DILocationVerifier : MachineFunction::Delegate {
+  MachineFunction &MF;
+  const Instruction *CurrInst = nullptr;
+
+public:
+  DILocationVerifier(MachineFunction &MF) : MF(MF) { MF.setDelegate(this); }
+  ~DILocationVerifier() { MF.resetDelegate(this); }
+
+  const Instruction *getCurrentInst() const { return CurrInst; }
+  void setCurrentInst(const Instruction *Inst) { CurrInst = Inst; }
+
+  void MF_HandleInsertion(const MachineInstr &MI) override {
+    assert(getCurrentInst() && "Inserted instruction without a current MI");
+
+    // Only print the check message if we're actually checking it.
+#ifndef NDEBUG
+    LLVM_DEBUG(dbgs() << "Checking DILocation from " << *CurrInst
+                      << " was copied to " << MI);
+#endif
+    assert(CurrInst->getDebugLoc() == MI.getDebugLoc() &&
+           "Line info was not transferred to all instructions");
+  }
+  void MF_HandleRemoval(const MachineInstr &MI) override {}
+};
+#endif // ifndef NDEBUG
+
+
 void IRTranslator::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.addRequired<StackProtector>();
   AU.addRequired<TargetPassConfig>();
@@ -1468,9 +1498,16 @@ bool IRTranslator::translateAtomicRMW(const User &U,
 }
 
 void IRTranslator::finishPendingPhis() {
+#ifndef NDEBUG
+  DILocationVerifier Verifier(*MF);
+#endif // ifndef NDEBUG
   for (auto &Phi : PendingPHIs) {
     const PHINode *PI = Phi.first;
     ArrayRef<MachineInstr *> ComponentPHIs = Phi.second;
+    EntryBuilder.setDebugLoc(PI->getDebugLoc());
+#ifndef NDEBUG
+    Verifier.setCurrentInst(PI);
+#endif // ifndef NDEBUG
 
     // All MachineBasicBlocks exist, add them to the PHI. We assume IRTranslator
     // won't create extra control flow here, otherwise we need to find the
@@ -1509,6 +1546,7 @@ bool IRTranslator::valueIsSplit(const Value &V,
 
 bool IRTranslator::translate(const Instruction &Inst) {
   CurBuilder.setDebugLoc(Inst.getDebugLoc());
+  EntryBuilder.setDebugLoc(Inst.getDebugLoc());
   switch(Inst.getOpcode()) {
 #define HANDLE_INST(NUM, OPCODE, CLASS) \
     case Instruction::OPCODE: return translate##OPCODE(Inst, CurBuilder);
@@ -1684,31 +1722,39 @@ bool IRTranslator::runOnMachineFunction(MachineFunction &CurMF) {
   }
 
   // Need to visit defs before uses when translating instructions.
-  ReversePostOrderTraversal<const Function *> RPOT(&F);
-  for (const BasicBlock *BB : RPOT) {
-    MachineBasicBlock &MBB = getMBB(*BB);
-    // Set the insertion point of all the following translations to
-    // the end of this basic block.
-    CurBuilder.setMBB(MBB);
-
-    for (const Instruction &Inst : *BB) {
-      if (translate(Inst))
-        continue;
-
-      OptimizationRemarkMissed R("gisel-irtranslator", "GISelFailure",
-                                 Inst.getDebugLoc(), BB);
-      R << "unable to translate instruction: " << ore::NV("Opcode", &Inst);
-
-      if (ORE->allowExtraAnalysis("gisel-irtranslator")) {
-        std::string InstStrStorage;
-        raw_string_ostream InstStr(InstStrStorage);
-        InstStr << Inst;
+  {
+    ReversePostOrderTraversal<const Function *> RPOT(&F);
+#ifndef NDEBUG
+    DILocationVerifier Verifier(*MF);
+#endif // ifndef NDEBUG
+    for (const BasicBlock *BB : RPOT) {
+      MachineBasicBlock &MBB = getMBB(*BB);
+      // Set the insertion point of all the following translations to
+      // the end of this basic block.
+      CurBuilder.setMBB(MBB);
+
+      for (const Instruction &Inst : *BB) {
+#ifndef NDEBUG
+        Verifier.setCurrentInst(&Inst);
+#endif // ifndef NDEBUG
+        if (translate(Inst))
+          continue;
+
+        OptimizationRemarkMissed R("gisel-irtranslator", "GISelFailure",
+                                   Inst.getDebugLoc(), BB);
+        R << "unable to translate instruction: " << ore::NV("Opcode", &Inst);
+
+        if (ORE->allowExtraAnalysis("gisel-irtranslator")) {
+          std::string InstStrStorage;
+          raw_string_ostream InstStr(InstStrStorage);
+          InstStr << Inst;
+
+          R << ": '" << InstStr.str() << "'";
+        }
 
-        R << ": '" << InstStr.str() << "'";
+        reportTranslationError(*MF, *TPC, *ORE, R);
+        return false;
       }
-
-      reportTranslationError(*MF, *TPC, *ORE, R);
-      return false;
     }
   }
 

test/CodeGen/AArch64/GlobalISel/irtranslator-dilocation.ll

@@ -0,0 +1,51 @@
+; RUN: llc -O0 -mtriple=aarch64-apple-ios -global-isel -debug-only=irtranslator \
+; RUN:     -stop-after=irtranslator %s -o - 2>&1 | FileCheck %s
+
+; CHECK: Checking DILocation from   %retval = alloca i32, align 4 was copied to G_FRAME_INDEX
+; CHECK: Checking DILocation from   %rv = alloca i32, align 4 was copied to G_FRAME_INDEX
+; CHECK: Checking DILocation from   store i32 0, i32* %retval, align 4 was copied to G_CONSTANT
+; CHECK: Checking DILocation from   store i32 0, i32* %retval, align 4 was copied to G_STORE
+; CHECK: Checking DILocation from   store i32 0, i32* %rv, align 4, !dbg !12 was copied to G_STORE debug-location !12; t.cpp:2:5
+; CHECK: Checking DILocation from   %0 = load i32, i32* %rv, align 4, !dbg !13 was copied to G_LOAD debug-location !13; t.cpp:3:8
+; CHECK: Checking DILocation from   ret i32 %0, !dbg !14 was copied to COPY debug-location !14; t.cpp:3:1
+; CHECK: Checking DILocation from   ret i32 %0, !dbg !14 was copied to RET_ReallyLR implicit $w0, debug-location !14; t.cpp:3:1
+
+source_filename = "t.cpp"
+target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
+target triple = "arm64-unknown-linux-gnu"
+
+; Function Attrs: noinline norecurse nounwind optnone
+define dso_local i32 @main() !dbg !7 {
+entry:
+  %retval = alloca i32, align 4
+  %rv = alloca i32, align 4
+  store i32 0, i32* %retval, align 4
+  call void @llvm.dbg.declare(metadata i32* %rv, metadata !11, metadata !DIExpression()), !dbg !12
+  store i32 0, i32* %rv, align 4, !dbg !12
+  %0 = load i32, i32* %rv, align 4, !dbg !13
+  ret i32 %0, !dbg !14
+}
+
+; Function Attrs: nounwind readnone speculatable
+declare void @llvm.dbg.declare(metadata, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 8.0.0 (trunk) (llvm/trunk 344296)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
+!1 = !DIFile(filename: "t.cpp", directory: "/Volumes/Data/llvm.org/svn/build")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 8.0.0 (trunk) (llvm/trunk 344296)"}
+!7 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 1, type: !8, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: false, unit: !0, retainedNodes: !2)
+!8 = !DISubroutineType(types: !9)
+!9 = !{!10}
+!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!11 = !DILocalVariable(name: "rv", scope: !7, file: !1, line: 2, type: !10)
+!12 = !DILocation(line: 2, column: 5, scope: !7)
+!13 = !DILocation(line: 3, column: 8, scope: !7)
+!14 = !DILocation(line: 3, column: 1, scope: !7)
+