DebugInfo: Use the SPMap to find the parent CU of inlined functions as they may not be in the current CU

Committed in r209178 then reverted in r209251 due to LTO breakage,
here's a proper fix for the case of the missing subprogram DIE. The DIEs
were there, just in other compile units. Using the SPMap we can find the
right compile unit to search for and produce cross-unit references to
describe this kind of inlining.

One existing test case needed to be updated because it had a function
that wasn't in the CU's subprogram list, so it didn't appear in the
SPMap.

llvm-svn: 209335

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -431,14 +431,10 @@ DwarfDebug::constructInlinedScopeDIE(DwarfCompileUnit &TheCU,
   assert(Scope->getScopeNode());
   DIScope DS(Scope->getScopeNode());
   DISubprogram InlinedSP = getDISubprogram(DS);
-  DIE *OriginDIE = TheCU.getDIE(InlinedSP);
+  // Find the subprogram's DwarfCompileUnit in the SPMap in case the subprogram
-  // FIXME: This should be an assert (or possibly a
+  // was inlined from another compile unit.
-  // getOrCreateSubprogram(InlinedSP)) otherwise we're just failing to emit
+  DIE *OriginDIE = SPMap[InlinedSP]->getDIE(InlinedSP);
-  // inlining information.
+  assert(OriginDIE && "Unable to find original DIE for an inlined subprogram.");
-  if (!OriginDIE) {
-    DEBUG(dbgs() << "Unable to find original DIE for an inlined subprogram.");
-    return nullptr;
-  }
 
   auto ScopeDIE = make_unique<DIE>(dwarf::DW_TAG_inlined_subroutine);
   TheCU.addDIEEntry(*ScopeDIE, dwarf::DW_AT_abstract_origin, *OriginDIE);
@@ -530,12 +526,14 @@ void DwarfDebug::constructAbstractSubprogramScopeDIE(DwarfCompileUnit &TheCU,
   if (!ProcessedSPNodes.insert(Sub))
     return;
 
-  if (DIE *ScopeDIE = TheCU.getDIE(Sub)) {
+  // Find the subprogram's DwarfCompileUnit in the SPMap in case the subprogram
+  // was inlined from another compile unit.
+  DIE *ScopeDIE = SPMap[Sub]->getDIE(Sub);
+  assert(ScopeDIE);
   AbstractSPDies.insert(std::make_pair(Sub, ScopeDIE));
   TheCU.addUInt(*ScopeDIE, dwarf::DW_AT_inline, None, dwarf::DW_INL_inlined);
   createAndAddScopeChildren(TheCU, Scope, *ScopeDIE);
 }
-}
 
 DIE &DwarfDebug::constructSubprogramScopeDIE(DwarfCompileUnit &TheCU,
                                              LexicalScope *Scope) {

llvm/test/CodeGen/Thumb/2010-07-15-debugOrdering.ll

@@ -151,5 +151,5 @@ declare void @llvm.dbg.value(metadata, i64, metadata) nounwind readnone
 !98 = metadata !{i32 52, i32 0, metadata !1, null}
 !101 = metadata !{metadata !"ggEdgeDiscrepancy.cc", metadata !"/Volumes/Home/grosbaj/sources/llvm-externals/speccpu2000/benchspec/CINT2000/252.eon/src"}
 !102 = metadata !{i32 0}
-!103 = metadata !{metadata !3}
+!103 = metadata !{metadata !3, metadata !77}
 !104 = metadata !{i32 1, metadata !"Debug Info Version", i32 1}

llvm/test/DebugInfo/cross-cu-inlining.ll

@@ -0,0 +1,124 @@
+; REQUIRES: object-emission
+
+; RUN: %llc_dwarf -O0 -filetype=obj < %s | llvm-dwarfdump -debug-dump=info - | FileCheck %s
+
+; Build from source:
+; $ clang++ a.cpp b.cpp -g -c -emit-llvm
+; $ llvm-link a.bc b.bc -o ab.bc
+; $ opt -inline ab.bc -o ab-opt.bc
+; $ cat a.cpp
+; extern int i;
+; int func(int);
+; int main() {
+;   return func(i);
+; }
+; $ cat b.cpp
+; int __attribute__((always_inline)) func(int x) {
+;   return x * 2;
+; }
+
+; Ensure that func inlined into main is described and references the abstract
+; definition in b.cpp's CU.
+
+; CHECK: DW_TAG_compile_unit
+; CHECK:   DW_AT_name {{.*}} "a.cpp"
+; CHECK:   DW_TAG_subprogram
+; CHECK:     DW_TAG_inlined_subroutine
+; CHECK-NEXT:       DW_AT_abstract_origin {{.*}}[[ABS_FUNC:........]])
+; CHECK:       DW_TAG_formal_parameter
+; CHECK-NEXT:         DW_AT_abstract_origin {{.*}}[[ABS_VAR:........]])
+
+; Check the abstract definition is in the 'b.cpp' CU and doesn't contain any
+; concrete information (address range or variable location)
+; CHECK: DW_TAG_compile_unit
+; CHECK:   DW_AT_name {{.*}} "b.cpp"
+; CHECK: 0x[[ABS_FUNC]]: DW_TAG_subprogram
+; CHECK-NOT: DW_AT_low_pc
+; CHECK: 0x[[ABS_VAR]]: DW_TAG_formal_parameter
+; CHECK-NOT: DW_AT_location
+
+; Check the concrete out of line definition references the abstract and
+; provides the address range and variable location
+; CHECK: DW_TAG_subprogram
+; CHECK-NEXT:   DW_AT_abstract_origin {{.*}} {0x[[ABS_FUNC]]}
+; CHECK:   DW_AT_low_pc
+; CHECK:   DW_TAG_formal_parameter
+; CHECK-NEXT:     DW_AT_abstract_origin {{.*}} {0x[[ABS_VAR]]}
+; CHECK:     DW_AT_location
+
+
+@i = external global i32
+
+; Function Attrs: uwtable
+define i32 @main() #0 {
+entry:
+  %x.addr.i = alloca i32, align 4
+  %retval = alloca i32, align 4
+  store i32 0, i32* %retval
+  %0 = load i32* @i, align 4, !dbg !19
+  %1 = bitcast i32* %x.addr.i to i8*
+  call void @llvm.lifetime.start(i64 4, i8* %1)
+  store i32 %0, i32* %x.addr.i, align 4
+  call void @llvm.dbg.declare(metadata !{i32* %x.addr.i}, metadata !20), !dbg !21
+  %2 = load i32* %x.addr.i, align 4, !dbg !22
+  %mul.i = mul nsw i32 %2, 2, !dbg !22
+  %3 = bitcast i32* %x.addr.i to i8*, !dbg !22
+  call void @llvm.lifetime.end(i64 4, i8* %3), !dbg !22
+  ret i32 %mul.i, !dbg !19
+}
+
+; Function Attrs: alwaysinline nounwind uwtable
+define i32 @_Z4funci(i32 %x) #1 {
+entry:
+  %x.addr = alloca i32, align 4
+  store i32 %x, i32* %x.addr, align 4
+  call void @llvm.dbg.declare(metadata !{i32* %x.addr}, metadata !20), !dbg !23
+  %0 = load i32* %x.addr, align 4, !dbg !24
+  %mul = mul nsw i32 %0, 2, !dbg !24
+  ret i32 %mul, !dbg !24
+}
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata) #2
+
+; Function Attrs: nounwind
+declare void @llvm.lifetime.start(i64, i8* nocapture) #3
+
+; Function Attrs: nounwind
+declare void @llvm.lifetime.end(i64, i8* nocapture) #3
+
+attributes #0 = { uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { alwaysinline nounwind uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #2 = { nounwind readnone }
+attributes #3 = { nounwind }
+
+!llvm.dbg.cu = !{!0, !9}
+!llvm.module.flags = !{!16, !17}
+!llvm.ident = !{!18, !18}
+
+!0 = metadata !{i32 786449, metadata !1, i32 4, metadata !"clang version 3.5.0 ", i1 false, metadata !"", i32 0, metadata !2, metadata !2, metadata !3, metadata !2, metadata !2, metadata !"", i32 1} ; [ DW_TAG_compile_unit ] [/tmp/dbginfo/a.cpp] [DW_LANG_C_plus_plus]
+!1 = metadata !{metadata !"a.cpp", metadata !"/tmp/dbginfo"}
+!2 = metadata !{}
+!3 = metadata !{metadata !4}
+!4 = metadata !{i32 786478, metadata !1, metadata !5, metadata !"main", metadata !"main", metadata !"", i32 3, metadata !6, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 false, i32 ()* @main, null, null, metadata !2, i32 3} ; [ DW_TAG_subprogram ] [line 3] [def] [main]
+!5 = metadata !{i32 786473, metadata !1}          ; [ DW_TAG_file_type ] [/tmp/dbginfo/a.cpp]
+!6 = metadata !{i32 786453, i32 0, null, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !7, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!7 = metadata !{metadata !8}
+!8 = metadata !{i32 786468, null, null, metadata !"int", i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ] [int] [line 0, size 32, align 32, offset 0, enc DW_ATE_signed]
+!9 = metadata !{i32 786449, metadata !10, i32 4, metadata !"clang version 3.5.0 ", i1 false, metadata !"", i32 0, metadata !2, metadata !2, metadata !11, metadata !2, metadata !2, metadata !"", i32 1} ; [ DW_TAG_compile_unit ] [/tmp/dbginfo/b.cpp] [DW_LANG_C_plus_plus]
+!10 = metadata !{metadata !"b.cpp", metadata !"/tmp/dbginfo"}
+!11 = metadata !{metadata !12}
+!12 = metadata !{i32 786478, metadata !10, metadata !13, metadata !"func", metadata !"func", metadata !"_Z4funci", i32 1, metadata !14, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 false, i32 (i32)* @_Z4funci, null, null, metadata !2, i32 1} ; [ DW_TAG_subprogram ] [line 1] [def] [func]
+!13 = metadata !{i32 786473, metadata !10}        ; [ DW_TAG_file_type ] [/tmp/dbginfo/b.cpp]
+!14 = metadata !{i32 786453, i32 0, null, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !15, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!15 = metadata !{metadata !8, metadata !8}
+!16 = metadata !{i32 2, metadata !"Dwarf Version", i32 4}
+!17 = metadata !{i32 2, metadata !"Debug Info Version", i32 1}
+!18 = metadata !{metadata !"clang version 3.5.0 "}
+!19 = metadata !{i32 4, i32 0, metadata !4, null}
+!20 = metadata !{i32 786689, metadata !12, metadata !"x", metadata !13, i32 16777217, metadata !8, i32 0, i32 0} ; [ DW_TAG_arg_variable ] [x] [line 1]
+!21 = metadata !{i32 1, i32 0, metadata !12, metadata !19}
+!22 = metadata !{i32 2, i32 0, metadata !12, metadata !19}
+!23 = metadata !{i32 1, i32 0, metadata !12, null}
+!24 = metadata !{i32 2, i32 0, metadata !12, null}
+