[DEBUG_INFO, NVPTX] Fix relocation info.

Summary: Initial function labels must follow the debug location for the correct relocation info generation.

Reviewers: tra, jlebar, echristo

Subscribers: jholewinski, llvm-commits

Differential Revision: https://reviews.llvm.org/D45784

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@351843 91177308-0d34-0410-b5e6-96231b3b80d8

Author: alexey-bataev

include/llvm/CodeGen/AsmPrinter.h

@@ -226,6 +226,9 @@ class AsmPrinter : public MachineFunctionPass {
 
   void EmitToStreamer(MCStreamer &S, const MCInst &Inst);
 
+  /// Emits inital debug location directive.
+  void emitInitialRawDwarfLocDirective(const MachineFunction &MF);
+
   /// Return the current section we are emitting to.
   const MCSection *getCurrentSection() const;
 

lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -231,6 +231,12 @@ void AsmPrinter::EmitToStreamer(MCStreamer &S, const MCInst &Inst) {
   S.EmitInstruction(Inst, getSubtargetInfo());
 }
 
+void AsmPrinter::emitInitialRawDwarfLocDirective(const MachineFunction &MF) {
+  assert(DD && "Dwarf debug file is not defined.");
+  assert(OutStreamer->hasRawTextSupport() && "Expected assembly output mode.");
+  (void)DD->emitInitialLocDirective(MF, /*CUID=*/0);
+}
+
 /// getCurrentSection() - Return the current section we are emitting to.
 const MCSection *AsmPrinter::getCurrentSection() const {
   return OutStreamer->getCurrentSectionOnly();

lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -1520,6 +1520,46 @@ static DebugLoc findPrologueEndLoc(const MachineFunction *MF) {
   return DebugLoc();
 }
 
+/// Register a source line with debug info. Returns the  unique label that was
+/// emitted and which provides correspondence to the source line list.
+static void recordSourceLine(AsmPrinter &Asm, unsigned Line, unsigned Col,
+                             const MDNode *S, unsigned Flags, unsigned CUID,
+                             uint16_t DwarfVersion,
+                             ArrayRef<std::unique_ptr<DwarfCompileUnit>> DCUs) {
+  StringRef Fn;
+  unsigned FileNo = 1;
+  unsigned Discriminator = 0;
+  if (auto *Scope = cast_or_null<DIScope>(S)) {
+    Fn = Scope->getFilename();
+    if (Line != 0 && DwarfVersion >= 4)
+      if (auto *LBF = dyn_cast<DILexicalBlockFile>(Scope))
+        Discriminator = LBF->getDiscriminator();
+
+    FileNo = static_cast<DwarfCompileUnit &>(*DCUs[CUID])
+                 .getOrCreateSourceID(Scope->getFile());
+  }
+  Asm.OutStreamer->EmitDwarfLocDirective(FileNo, Line, Col, Flags, 0,
+                                         Discriminator, Fn);
+}
+
+DebugLoc DwarfDebug::emitInitialLocDirective(const MachineFunction &MF,
+                                             unsigned CUID) {
+  // Get beginning of function.
+  if (DebugLoc PrologEndLoc = findPrologueEndLoc(&MF)) {
+    // Ensure the compile unit is created if the function is called before
+    // beginFunction().
+    (void)getOrCreateDwarfCompileUnit(
+        MF.getFunction().getSubprogram()->getUnit());
+    // We'd like to list the prologue as "not statements" but GDB behaves
+    // poorly if we do that. Revisit this with caution/GDB (7.5+) testing.
+    const DISubprogram *SP = PrologEndLoc->getInlinedAtScope()->getSubprogram();
+    ::recordSourceLine(*Asm, SP->getScopeLine(), 0, SP, DWARF2_FLAG_IS_STMT,
+                       CUID, getDwarfVersion(), getUnits());
+    return PrologEndLoc;
+  }
+  return DebugLoc();
+}
+
 // Gather pre-function debug information.  Assumes being called immediately
 // after the function entry point has been emitted.
 void DwarfDebug::beginFunctionImpl(const MachineFunction *MF) {
@@ -1542,13 +1582,8 @@ void DwarfDebug::beginFunctionImpl(const MachineFunction *MF) {
     Asm->OutStreamer->getContext().setDwarfCompileUnitID(CU.getUniqueID());
 
   // Record beginning of function.
-  PrologEndLoc = findPrologueEndLoc(MF);
-  if (PrologEndLoc) {
-    // We'd like to list the prologue as "not statements" but GDB behaves
-    // poorly if we do that. Revisit this with caution/GDB (7.5+) testing.
-    auto *SP = PrologEndLoc->getInlinedAtScope()->getSubprogram();
-    recordSourceLine(SP->getScopeLine(), 0, SP, DWARF2_FLAG_IS_STMT);
-  }
+  PrologEndLoc = emitInitialLocDirective(
+      *MF, Asm->OutStreamer->getContext().getDwarfCompileUnitID());
 }
 
 void DwarfDebug::skippedNonDebugFunction() {
@@ -1646,21 +1681,9 @@ void DwarfDebug::endFunctionImpl(const MachineFunction *MF) {
 // emitted and which provides correspondence to the source line list.
 void DwarfDebug::recordSourceLine(unsigned Line, unsigned Col, const MDNode *S,
                                   unsigned Flags) {
-  StringRef Fn;
-  unsigned FileNo = 1;
-  unsigned Discriminator = 0;
-  if (auto *Scope = cast_or_null<DIScope>(S)) {
-    Fn = Scope->getFilename();
-    if (Line != 0 && getDwarfVersion() >= 4)
-      if (auto *LBF = dyn_cast<DILexicalBlockFile>(Scope))
-        Discriminator = LBF->getDiscriminator();
-
-    unsigned CUID = Asm->OutStreamer->getContext().getDwarfCompileUnitID();
-    FileNo = static_cast<DwarfCompileUnit &>(*InfoHolder.getUnits()[CUID])
-              .getOrCreateSourceID(Scope->getFile());
-  }
-  Asm->OutStreamer->EmitDwarfLocDirective(FileNo, Line, Col, Flags, 0,
-                                          Discriminator, Fn);
+  ::recordSourceLine(*Asm, Line, Col, S, Flags,
+                     Asm->OutStreamer->getContext().getDwarfCompileUnitID(),
+                     getDwarfVersion(), getUnits());
 }
 
 //===----------------------------------------------------------------------===//

lib/CodeGen/AsmPrinter/DwarfDebug.h

@@ -592,6 +592,9 @@ class DwarfDebug : public DebugHandlerBase {
   /// Emit all Dwarf sections that should come after the content.
   void endModule() override;
 
+  /// Emits inital debug location directive.
+  DebugLoc emitInitialLocDirective(const MachineFunction &MF, unsigned CUID);
+
   /// Process beginning of an instruction.
   void beginInstruction(const MachineInstr *MI) override;
 

lib/Target/NVPTX/NVPTXAsmPrinter.cpp

@@ -472,6 +472,9 @@ void NVPTXAsmPrinter::EmitFunctionEntryLabel() {
   // Emit open brace for function body.
   OutStreamer->EmitRawText(StringRef("{\n"));
   setAndEmitFunctionVirtualRegisters(*MF);
+  // Emit initial .loc debug directive for correct relocation symbol data.
+  if (MMI && MMI->hasDebugInfo())
+    emitInitialRawDwarfLocDirective(*MF);
 }
 
 bool NVPTXAsmPrinter::runOnMachineFunction(MachineFunction &F) {

test/DebugInfo/NVPTX/cu-range-hole.ll

@@ -6,6 +6,7 @@
 ; CHECK: .param .b32 b_param_0
 ; CHECK: )
 ; CHECK: {
+; CHECK: .loc 1 1 0
 ; CHECK: Lfunc_begin0:
 ; CHECK: .loc 1 1 0
 ; CHECK: .loc 1 1 0
@@ -27,6 +28,7 @@
 ; CHECK: .param .b32 d_param_0
 ; CHECK: )
 ; CHECK: {
+; CHECK: .loc 1 3 0
 ; CHECK: Lfunc_begin2:
 ; CHECK: .loc 1 3 0
 ; CHECK: ret;

test/DebugInfo/NVPTX/debug-loc-offset.ll

@@ -11,8 +11,9 @@
 
 ; CHECK: .visible .func  (.param .b32 func_retval0) _Z3bari(
 ; CHECK: {
-; CHECK: Lfunc_begin0:
 ; CHECK: .loc [[CU1:[0-9]+]] 1 0
+; CHECK: Lfunc_begin0:
+; CHECK: .loc [[CU1]] 1 0
 
 ; CHECK: //DEBUG_VALUE: bar:b <- {{[0-9]+}}
 ; CHECK: //DEBUG_VALUE: bar:b <- {{[0-9]+}}
@@ -39,8 +40,9 @@ declare void @llvm.dbg.value(metadata, metadata, metadata) #1
 
 ; CHECK: .visible .func _Z3baz1A(
 ; CHECK: {
-; CHECK: Lfunc_begin1:
 ; CHECK: .loc [[CU2:[0-9]+]] 6 0
+; CHECK: Lfunc_begin1:
+; CHECK: .loc [[CU2]] 6 0
 ; CHECK: //DEBUG_VALUE: baz:z <- {{[0-9]+}}
 ; CHECK: //DEBUG_VALUE: baz:z <- {{[0-9]+}}
 ; CHECK: .loc [[CU2]] 10 0