DebugInfo: Emit ranges for functions with DISubprograms but lacking locations on any instructions

This seems more consistent, and helps tidy up/simplify some other code
in this change.

llvm-svn: 289889

llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp

@@ -568,25 +568,24 @@ DIE *DwarfCompileUnit::createScopeChildrenDIE(LexicalScope *Scope,
   return ObjectPointer;
 }
 
-void DwarfCompileUnit::constructSubprogramScopeDIE(LexicalScope *Scope) {
-  assert(Scope && Scope->getScopeNode());
-  assert(!Scope->getInlinedAt());
-  assert(!Scope->isAbstractScope());
-  auto *Sub = cast<DISubprogram>(Scope->getScopeNode());
-
+void DwarfCompileUnit::constructSubprogramScopeDIE(const DISubprogram *Sub, LexicalScope *Scope) {
   DD->getProcessedSPNodes().insert(Sub);
 
   DIE &ScopeDIE = updateSubprogramScopeDIE(Sub);
 
+  if (Scope) {
+    assert(!Scope->getInlinedAt());
+    assert(!Scope->isAbstractScope());
+    // Collect lexical scope children first.
+    // ObjectPointer might be a local (non-argument) local variable if it's a
+    // block's synthetic this pointer.
+    if (DIE *ObjectPointer = createAndAddScopeChildren(Scope, ScopeDIE))
+      addDIEEntry(ScopeDIE, dwarf::DW_AT_object_pointer, *ObjectPointer);
+  }
+
   // If this is a variadic function, add an unspecified parameter.
   DITypeRefArray FnArgs = Sub->getType()->getTypeArray();
 
-  // Collect lexical scope children first.
-  // ObjectPointer might be a local (non-argument) local variable if it's a
-  // block's synthetic this pointer.
-  if (DIE *ObjectPointer = createAndAddScopeChildren(Scope, ScopeDIE))
-    addDIEEntry(ScopeDIE, dwarf::DW_AT_object_pointer, *ObjectPointer);
-
   // If we have a single element of null, it is a function that returns void.
   // If we have more than one elements and the last one is null, it is a
   // variadic function.
@@ -678,11 +677,7 @@ void DwarfCompileUnit::finishSubprogramDefinition(const DISubprogram *SP) {
       // If this subprogram has an abstract definition, reference that
       addDIEEntry(*D, dwarf::DW_AT_abstract_origin, *AbsSPDIE);
   } else {
-    if (!D && !includeMinimalInlineScopes())
-      // Lazily construct the subprogram if we didn't see either concrete or
-      // inlined versions during codegen. (except in -gmlt ^ where we want
-      // to omit these entirely)
-      D = getOrCreateSubprogramDIE(SP);
+    assert(D || includeMinimalInlineScopes());
     if (D)
       // And attach the attributes
       applySubprogramAttributesToDefinition(SP, *D);

llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h

@@ -172,7 +172,7 @@ public:
                               unsigned *ChildScopeCount = nullptr);
 
   /// \brief Construct a DIE for this subprogram scope.
-  void constructSubprogramScopeDIE(LexicalScope *Scope);
+  void constructSubprogramScopeDIE(const DISubprogram *Sub, LexicalScope *Scope);
 
   DIE *createAndAddScopeChildren(LexicalScope *Scope, DIE &ScopeDIE);
 

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -1155,18 +1155,14 @@ void DwarfDebug::endFunction(const MachineFunction *MF) {
       "endFunction should be called with the same function as beginFunction");
 
   const DISubprogram *SP = MF->getFunction()->getSubprogram();
-  if (!MMI->hasDebugInfo() || LScopes.empty() || !SP ||
+  if (!MMI->hasDebugInfo() || !SP ||
       SP->getUnit()->getEmissionKind() == DICompileUnit::NoDebug) {
-    // If we don't have a lexical scope for this function then there will
-    // be a hole in the range information. Keep note of this by setting the
-    // previously used section to nullptr.
+    // If we don't have a subprogram for this function then there will be a hole
+    // in the range information. Keep note of this by setting the previously
+    // used section to nullptr.
     PrevCU = nullptr;
     CurFn = nullptr;
     DebugHandlerBase::endFunction(MF);
-    // Mark functions with no debug info on any instructions, but a
-    // valid DISubprogram as processed.
-    if (SP)
-      ProcessedSPNodes.insert(SP);
     return;
   }
 
@@ -1174,7 +1170,7 @@ void DwarfDebug::endFunction(const MachineFunction *MF) {
   Asm->OutStreamer->getContext().setDwarfCompileUnitID(0);
 
   LexicalScope *FnScope = LScopes.getCurrentFunctionScope();
-  SP = cast<DISubprogram>(FnScope->getScopeNode());
+  assert(!FnScope || SP == FnScope->getScopeNode());
   DwarfCompileUnit &TheCU = *CUMap.lookup(SP->getUnit());
 
   DenseSet<InlinedVariable> ProcessedVars;
@@ -1216,11 +1212,11 @@ void DwarfDebug::endFunction(const MachineFunction *MF) {
     constructAbstractSubprogramScopeDIE(AScope);
   }
 
-  TheCU.constructSubprogramScopeDIE(FnScope);
+  TheCU.constructSubprogramScopeDIE(SP, FnScope);
   if (auto *SkelCU = TheCU.getSkeleton())
     if (!LScopes.getAbstractScopesList().empty() &&
         TheCU.getCUNode()->getSplitDebugInlining())
-      SkelCU->constructSubprogramScopeDIE(FnScope);
+      SkelCU->constructSubprogramScopeDIE(SP, FnScope);
 
   // Clear debug info
   // Ownership of DbgVariables is a bit subtle - ScopeVariables owns all the

llvm/test/DebugInfo/Generic/2010-10-01-crash.ll

@@ -13,7 +13,7 @@ declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture, i32, i32,
 
 !llvm.dbg.cu = !{!2}
 !llvm.module.flags = !{!27}
-!0 = distinct !DISubprogram(name: "CGRectStandardize", linkageName: "CGRectStandardize", line: 54, isLocal: false, isDefinition: true, virtualIndex: 6, isOptimized: false, unit: !2, file: !1, scope: null)
+!0 = distinct !DISubprogram(name: "CGRectStandardize", linkageName: "CGRectStandardize", line: 54, isLocal: false, isDefinition: true, virtualIndex: 6, isOptimized: false, unit: !2, file: !1, scope: null, type: !28)
 !1 = !DIFile(filename: "GSFusedSilica.m", directory: "/Volumes/Data/Users/sabre/Desktop")
 !2 = distinct !DICompileUnit(language: DW_LANG_ObjC, producer: "clang version 2.9 (trunk 115292)", isOptimized: true, runtimeVersion: 1, emissionKind: FullDebug, file: !25, enums: !26, retainedTypes: !26)
 !5 = !DIDerivedType(tag: DW_TAG_typedef, name: "CGRect", line: 49, file: !25, baseType: null)
@@ -22,3 +22,5 @@ declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture, i32, i32,
 !25 = !DIFile(filename: "GSFusedSilica.m", directory: "/Volumes/Data/Users/sabre/Desktop")
 !26 = !{}
 !27 = !{i32 1, !"Debug Info Version", i32 3}
+!28 = !DISubroutineType(types: !29)
+!29 = !{null}

llvm/test/DebugInfo/Generic/noscopes.ll

@@ -0,0 +1,40 @@
+; REQUIRES: object-emission
+
+; RUN: %llc_dwarf -O0 -filetype=obj < %s | llvm-dwarfdump - | FileCheck %s
+
+; Just because there are no scopes/locations on any instructions in the
+; function doesn't mean we can't describe the address range of the function.
+; Check that we do that
+
+; CHECK: DW_TAG_subprogram
+; CHECK-NOT: TAG
+; CHECK:   DW_AT_low_pc
+
+; ModuleID = 'noscopes.c'
+source_filename = "noscopes.c"
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Function Attrs: nounwind uwtable
+define void @f() #0 !dbg !6 {
+entry:
+  ret void
+}
+
+attributes #0 = { nounwind uwtable "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+!llvm.ident = !{!5}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 4.0.0 (trunk 289692) (llvm/trunk 289697)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
+!1 = !DIFile(filename: "noscopes.c", directory: "/tmp/dbginfo")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{!"clang version 4.0.0 (trunk 289692) (llvm/trunk 289697)"}
+!6 = distinct !DISubprogram(name: "f", scope: !1, file: !1, line: 1, type: !7, isLocal: false, isDefinition: true, scopeLine: 1, isOptimized: false, unit: !0, variables: !2)
+!7 = !DISubroutineType(types: !8)
+!8 = !{null}
+!9 = !DILocation(line: 2, column: 1, scope: !6)
+