[llvm/DWARF] Return section offset from DWARFUnit::get{Loc,Rng}listOffset

Summary:
Currently these function return the raw content of the appropriate table
header, which means they are relative to the DW_AT_{loc,rng}list_base,
and one has to relocate them in order to do anything.

This changes the functions to perform the relocation themselves, which
seems more clearer, particularly as they are sitting right next to the
find{Rng,Loc}listFromOffset functions, but one *cannot* simply take the
result of these functions and take pass them there.

The only effect of this patch is to change what value is dumped for the
DW_AT_ranges attribute, which I think is for the better, as previously
the values appeared to point into thin air.

(The main reason I am looking at this is because I was trying to
implement equivalent functionality in lldb's DWARFUnit, and was stumped
by this behavior.

Reviewers: dblaikie, JDevlieghere, aprantl

Subscribers: hiraditya, llvm-commits, SouraVX

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D71006

7 files changed, 16 insertions, 12 deletions

diff --git a/llvm/include/llvm/DebugInfo/DWARF/DWARFUnit.h b/llvm/include/llvm/DebugInfo/DWARF/DWARFUnit.h
index 98d7a7ee3ca..36fdd511d1e 100644
--- a/llvm/include/llvm/DebugInfo/DWARF/DWARFUnit.h
+++ b/llvm/include/llvm/DebugInfo/DWARF/DWARFUnit.h
@@ -427,14 +427,18 @@ public:
   /// an entry in the rangelist table's offset array and is supplied by
   /// DW_FORM_rnglistx.
   Optional<uint64_t> getRnglistOffset(uint32_t Index) {
-    if (RngListTable)
-      return RngListTable->getOffsetEntry(Index);
+    if (!RngListTable)
+      return None;
+    if (Optional<uint64_t> Off = RngListTable->getOffsetEntry(Index))
+      return *Off + RangeSectionBase;
     return None;
   }
 
   Optional<uint64_t> getLoclistOffset(uint32_t Index) {
-    if (LoclistTableHeader)
-      return LoclistTableHeader->getOffsetEntry(Index);
+    if (!LoclistTableHeader)
+      return None;
+    if (Optional<uint64_t> Off = LoclistTableHeader->getOffsetEntry(Index))
+      return *Off + getLocSectionBase();
     return None;
   }
   Expected<DWARFAddressRangesVector> collectAddressRanges();
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFDie.cpp b/llvm/lib/DebugInfo/DWARF/DWARFDie.cpp
index 404bc13b178..4b86359c04e 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFDie.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFDie.cpp
@@ -91,7 +91,7 @@ static void dumpLocation(raw_ostream &OS, DWARFFormValue &FormValue,
       FormValue.dump(OS, DumpOpts);
 
       if (auto LoclistOffset = U->getLoclistOffset(Offset))
-        Offset = *LoclistOffset + U->getLocSectionBase();
+        Offset = *LoclistOffset;
       else
         return;
     }
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp b/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp
index b662e88816f..4ccda628093 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp
@@ -629,7 +629,7 @@ DWARFUnit::findRnglistFromOffset(uint64_t Offset) {
 Expected<DWARFAddressRangesVector>
 DWARFUnit::findRnglistFromIndex(uint32_t Index) {
   if (auto Offset = getRnglistOffset(Index))
-    return findRnglistFromOffset(*Offset + RangeSectionBase);
+    return findRnglistFromOffset(*Offset);
 
   if (RngListTable)
     return createStringError(errc::invalid_argument,
diff --git a/llvm/test/DebugInfo/X86/dwarfdump-rnglists-dwarf64.s b/llvm/test/DebugInfo/X86/dwarfdump-rnglists-dwarf64.s
index f8395818734..19bbd77586d 100644
--- a/llvm/test/DebugInfo/X86/dwarfdump-rnglists-dwarf64.s
+++ b/llvm/test/DebugInfo/X86/dwarfdump-rnglists-dwarf64.s
@@ -196,14 +196,14 @@ Range1_end:
 # CHECK-NOT:  Compile Unit:
 # CHECK:      DW_TAG_compile_unit
 # CHECK-NEXT: DW_AT_rnglists_base [DW_FORM_sec_offset]  (0x00000014)
-# CHECK-NEXT: DW_AT_ranges [DW_FORM_rnglistx] (indexed (0x1) rangelist = 0x00000020
+# CHECK-NEXT: DW_AT_ranges [DW_FORM_rnglistx] (indexed (0x1) rangelist = 0x00000034
 # CHECK-NEXT: [0x0000002a, 0x00000034) ".text")
 
 # CHECK:      .debug_info.dwo contents:
 # CHECK:      Compile Unit:
 # CHECK-NOT:  contents:
 # CHECK:      DW_TAG_compile_unit
-# CHECK-NEXT: DW_AT_ranges [DW_FORM_rnglistx] (indexed (0x1) rangelist = 0x00000011
+# CHECK-NEXT: DW_AT_ranges [DW_FORM_rnglistx] (indexed (0x1) rangelist = 0x00000025
 # CHECK-NEXT: [0x0000002a, 0x00000034))
 
 #ERR: error: parsing a range list table: did not detect a valid list table with base = 0x8
diff --git a/llvm/test/DebugInfo/X86/dwarfdump-rnglists.s b/llvm/test/DebugInfo/X86/dwarfdump-rnglists.s
index 7886374c4d6..0d6898df170 100644
--- a/llvm/test/DebugInfo/X86/dwarfdump-rnglists.s
+++ b/llvm/test/DebugInfo/X86/dwarfdump-rnglists.s
@@ -192,14 +192,14 @@ Range1_end:
 # CHECK-NOT:  Compile Unit:
 # CHECK:      DW_TAG_compile_unit
 # CHECK-NEXT: DW_AT_rnglists_base [DW_FORM_sec_offset]  (0x0000000c)
-# CHECK-NEXT: DW_AT_ranges [DW_FORM_rnglistx] (indexed (0x1) rangelist = 0x00000018
+# CHECK-NEXT: DW_AT_ranges [DW_FORM_rnglistx] (indexed (0x1) rangelist = 0x00000024
 # CHECK-NEXT: [0x0000002a, 0x00000034) ".text")
 
 # CHECK:      .debug_info.dwo contents:
 # CHECK:      Compile Unit:
 # CHECK-NOT:  contents:
 # CHECK:      DW_TAG_compile_unit
-# CHECK-NEXT: DW_AT_ranges [DW_FORM_rnglistx] (indexed (0x1) rangelist = 0x00000009
+# CHECK-NEXT: DW_AT_ranges [DW_FORM_rnglistx] (indexed (0x1) rangelist = 0x00000015
 # CHECK-NEXT: [0x0000002a, 0x00000034))
 
 #ERR: error: parsing a range list table: did not detect a valid list table with base = 0x8
diff --git a/llvm/test/DebugInfo/X86/split-dwarf-v5-ranges.ll b/llvm/test/DebugInfo/X86/split-dwarf-v5-ranges.ll
index 74e94643b9c..1761c4aa8fe 100644
--- a/llvm/test/DebugInfo/X86/split-dwarf-v5-ranges.ll
+++ b/llvm/test/DebugInfo/X86/split-dwarf-v5-ranges.ll
@@ -3,7 +3,7 @@
 
 ; CHECK: .debug_info contents:
 ; CHECK: .debug_info.dwo contents:
-; CHECK: DW_AT_ranges [DW_FORM_rnglistx] (indexed (0x0) rangelist = 0x00000004
+; CHECK: DW_AT_ranges [DW_FORM_rnglistx] (indexed (0x0) rangelist = 0x00000010
 ; CHECK:          [0x0000000000000001, 0x000000000000000c) ".text"
 ; CHECK:          [0x000000000000000e, 0x0000000000000013) ".text")
 
diff --git a/llvm/test/tools/llvm-dwarfdump/X86/no_debug_addr.s b/llvm/test/tools/llvm-dwarfdump/X86/no_debug_addr.s
index ce1ae23cf8d..bf660679837 100644
--- a/llvm/test/tools/llvm-dwarfdump/X86/no_debug_addr.s
+++ b/llvm/test/tools/llvm-dwarfdump/X86/no_debug_addr.s
@@ -4,7 +4,7 @@
 ## Ensure bogus empty section names are not printed when dumping
 ## rnglists that reference debug_addr when it is not present (such as in .dwo files)
 
-# CHECK:       DW_AT_ranges [DW_FORM_rnglistx]   (indexed (0x0) rangelist = 0x00000004
+# CHECK:       DW_AT_ranges [DW_FORM_rnglistx]   (indexed (0x0) rangelist = 0x00000010
 # CHECK-NEXT:    [0x0000000000000000, 0x0000000000000001)
 # CHECK-NEXT:    [0x0000000000000000, 0x0000000000000002))