Fix merging of debug_str_offsets with multiple contributions in the section

added test of merging contributions in debug_str_offsets

Author: molar

llvm/lib/DWP/DWP.cpp

@@ -415,6 +415,17 @@ Expected<InfoSectionUnitHeader> parseInfoSectionUnitHeader(StringRef Info) {
   return Header;
 }
 
+static void writeNewOffsetsTo(MCStreamer &Out, DataExtractor &Data,
+                              DenseMap<uint64_t, uint32_t> &OffsetRemapping,
+                              uint64_t &Offset, uint64_t &Size) {
+
+  while (Offset < Size) {
+    auto OldOffset = Data.getU32(&Offset);
+    auto NewOffset = OffsetRemapping[OldOffset];
+    Out.emitIntValue(NewOffset, 4);
+  }
+}
+
 void writeStringsAndOffsets(MCStreamer &Out, DWPStringPool &Strings,
                             MCSection *StrOffsetSection,
                             StringRef CurStrSection,
@@ -439,17 +450,30 @@ void writeStringsAndOffsets(MCStreamer &Out, DWPStringPool &Strings,
 
   Out.switchSection(StrOffsetSection);
 
-  uint64_t HeaderSize = debugStrOffsetsHeaderSize(Data, Version);
   uint64_t Offset = 0;
   uint64_t Size = CurStrOffsetSection.size();
-  // FIXME: This can be caused by bad input and should be handled as such.
-  assert(HeaderSize <= Size && "StrOffsetSection size is less than its header");
-  // Copy the header to the output.
-  Out.emitBytes(Data.getBytes(&Offset, HeaderSize));
-  while (Offset < Size) {
-    auto OldOffset = Data.getU32(&Offset);
-    auto NewOffset = OffsetRemapping[OldOffset];
-    Out.emitIntValue(NewOffset, 4);
+  if (Version > 4) {
+    while (Offset < Size) {
+      uint64_t HeaderSize = debugStrOffsetsHeaderSize(Data, Version);
+      assert(HeaderSize <= Size - Offset &&
+             "StrOffsetSection size is less than its header");
+
+      uint64_t ContributionEnd = 0;
+      uint64_t ContributionSize = 0;
+      uint64_t HeaderLengthOffset = Offset;
+      if (HeaderSize == 8) {
+        ContributionSize = Data.getU32(&HeaderLengthOffset);
+      } else if (HeaderSize == 16) {
+        HeaderLengthOffset += 4; // skip the dwarf64 marker
+        ContributionSize = Data.getU64(&HeaderLengthOffset);
+      }
+      ContributionEnd = ContributionSize + HeaderLengthOffset;
+      Out.emitBytes(Data.getBytes(&Offset, HeaderSize));
+      writeNewOffsetsTo(Out, Data, OffsetRemapping, Offset, ContributionEnd);
+    }
+
+  } else {
+    writeNewOffsetsTo(Out, Data, OffsetRemapping, Offset, Size);
   }
 }
 

llvm/test/tools/llvm-dwp/Inputs/merge_v5/notypes/ab.dwp

@@ -44,3 +44,8 @@ CHECK:    Index  Signature INFO                                        ABBREV
 CHECK-DAG:       [[DWOC]]  [0x00000000[[#COFF]], 0x00000000[[#AOFF]]) [0x0000[[CAOFF]], 0x0000[[AAOFF]]) [0x00000000, 0x00000011) [0x00000000, 0x00000018)
 CHECK-DAG:       [[DWOA]]  [0x00000000[[#AOFF]], 0x00000000[[#BOFF]]) [0x0000[[AAOFF]], 0x0000[[BAOFF]]) [0x00000011, 0x00000022) [0x00000018, 0x00000028)
 CHECK-DAG:       [[DWOB]]  [0x00000000[[#BOFF]], 0x00000000[[#XOFF]]) [0x0000[[BAOFF]], 0x000000c3)      [0x00000022, 0x00000033) [0x00000028, 0x0000003c)
+
+CHECK-LABEL: .debug_str_offsets.dwo contents:
+CHECK: Contribution size = 24, Format = DWARF32, Version = 4
+CHECK: Contribution size = 16, Format = DWARF32, Version = 4
+CHECK: Contribution size = 20, Format = DWARF32, Version = 4

llvm/test/tools/llvm-dwp/Inputs/merge_v5/notypes/c.dwo

@@ -0,0 +1,48 @@
+RUN: llvm-dwp %p/../Inputs/merge_v5/notypes/c.dwo %p/../Inputs/merge_v5/notypes/ab.dwp -o - | \
+RUN:   llvm-dwarfdump -v - | FileCheck --check-prefix=CHECK %s
+
+DWP from a DWO (c.dwo) and a DWP (ab.dwp, created from a.dwo and b.dwo)
+Make sure the entries for A and B are updated correctly when read/processed from ab.dwp
+a.cpp:
+  struct foo { };
+  foo a;
+
+b.cpp:
+  struct bar { };
+  void b(bar) {
+  }
+
+c.cpp:
+  typedef int baz;
+  baz c() {
+  }
+
+CHECK-LABEL: .debug_abbrev.dwo contents:
+CHECK-LABEL: Abbrev table for offset:
+CHECK: 0x0000[[CAOFF:.*]]
+CHECK-LABEL: Abbrev table for offset:
+CHECK: 0x0000[[AAOFF:.*]]
+CHECK-LABEL: Abbrev table for offset:
+CHECK: 0x0000[[BAOFF:.*]]
+
+CHECK: .debug_info.dwo contents:
+CHECK: 0x[[#%.8x,COFF:]]:
+CHECK-LABEL: Compile Unit: length = {{.*}}, format = DWARF32, version = 0x0005, unit_type = DW_UT_split_compile, abbr_offset =
+CHECK:         0x[[CAOFF]], addr_size = 0x08, DWO_id = 0x[[DWOC:.*]] (next unit at 0x[[#%.8x,BOFF:]])
+CHECK: [[#BOFF]]:
+CHECK-LABEL: Compile Unit: length = {{.*}}, format = DWARF32, version = 0x0005, unit_type = DW_UT_split_compile, abbr_offset =
+CHECK:         0x[[BAOFF]], addr_size = 0x08, DWO_id = 0x[[DWOB:.*]] (next unit at 0x[[#%.8x,AOFF:]])
+CHECK: [[#AOFF]]:
+CHECK-LABEL: Compile Unit: length = {{.*}}, format = DWARF32, version = 0x0005, unit_type = DW_UT_split_compile, abbr_offset =
+CHECK:         0x[[AAOFF]], addr_size = 0x08, DWO_id = 0x[[DWOA:.*]] (next unit at 0x[[#%.8x,XOFF:]])
+
+CHECK-LABEL: .debug_cu_index contents:
+CHECK:    Index Signature          INFO                                     ABBREV                                  STR_OFFSETS 
+CHECK-DAG:       [[DWOC]]  [0x00000000[[#COFF]], 0x00000000[[#BOFF]]) [0x0000[[CAOFF]], 0x0000[[AAOFF]]) [0x00000000, 0x00000024) 
+CHECK-DAG:       [[DWOB]]  [0x00000000[[#BOFF]], 0x00000000[[#AOFF]]) [0x0000[[BAOFF]],  
+CHECK-DAG:       [[DWOA]]  [0x00000000[[#AOFF]], 0x00000000[[#XOFF]]) [0x0000[[AAOFF]], 
+
+CHECK-LABEL: .debug_str_offsets.dwo contents:
+CHECK: Contribution size = 32, Format = DWARF32, Version = 5
+CHECK: Contribution size = 24, Format = DWARF32, Version = 5
+CHECK: Contribution size = 28, Format = DWARF32, Version = 5