DebugInfo: Include DW_AT_base_addr even in gmlt with no inline functions

Since the address pool doesn't get populated in this case (due to the
lack of inlining, no child DIEs are added to the CU - so no addresses
are needed for the DIEs themselves) until the range list is emitted - at
the time the attributes are added to the CU, the address pool is empty.
So check whether the address pool will be used for the range lists & add
an addr_base if that's the case.

Author: dwblaikie

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -1156,7 +1156,7 @@ void DwarfDebug::finalizeModuleInfo() {
 
     // We don't keep track of which addresses are used in which CU so this
     // is a bit pessimistic under LTO.
-    if (!AddrPool.isEmpty() &&
+    if ((!AddrPool.isEmpty() || TheCU.hasRangeLists()) &&
         (getDwarfVersion() >= 5 || HasSplitUnit))
       U.addAddrTableBase();
 

llvm/test/DebugInfo/X86/gmlt-empty-base-address.ll

@@ -0,0 +1,36 @@
+; RUN: %llc_dwarf --function-sections < %s -filetype=obj | llvm-dwarfdump -v -debug-info - | FileCheck %s
+
+; CHECK: DW_AT_ranges [DW_FORM_rnglistx]   (indexed (0x0) rangelist = 0x00000010
+; CHECK:                    [0x0000000000000000, 0x0000000000000006) ".text._Z2f1v"
+; CHECK:                    [0x0000000000000000, 0x0000000000000006) ".text._Z2f2v")
+; CHECK: DW_AT_addr_base [DW_FORM_sec_offset] (0x00000008)
+
+
+; Function A
+define dso_local void @_Z2f1v() #0 !dbg !7 {
+  ret void, !dbg !9
+}
+
+; Function Attrs: noinline nounwind optnone uwtable
+define dso_local void @_Z2f2v() #0 !dbg !10 {
+  ret void, !dbg !11
+}
+
+attributes #0 = { noinline nounwind optnone uwtable "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "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"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!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 10.0.0 (trunk 371665) (llvm/trunk 371681)", isOptimized: false, runtimeVersion: 0, emissionKind: LineTablesOnly, enums: !2, nameTableKind: None)
+!1 = !DIFile(filename: "gmlt-empty-base-address.cpp", directory: "/usr/local/google/home/blaikie/dev/scratch", checksumkind: CSK_MD5, checksum: "74f7c574cd1ba04403967d02e757afeb")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 5}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 10.0.0 (trunk 371665) (llvm/trunk 371681)"}
+!7 = distinct !DISubprogram(name: "f1", scope: !1, file: !1, line: 1, type: !8, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
+!8 = !DISubroutineType(types: !2)
+!9 = !DILocation(line: 2, column: 1, scope: !7)
+!10 = distinct !DISubprogram(name: "f2", scope: !1, file: !1, line: 3, type: !8, scopeLine: 3, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
+!11 = !DILocation(line: 4, column: 1, scope: !10)