[dsymutil] Fix handling of inlined_subprogram low_pcs

The value of an inlined subprogram low_pc attribute should not
get relocated, but it can happen that it matches the enclosing
function's start address and thus gets the generic treatment.
Special case it to avoid applying the PC offset twice.

llvm-svn: 246406

1 files changed, 14 insertions, 3 deletions

diff --git a/llvm/tools/dsymutil/DwarfLinker.cpp b/llvm/tools/dsymutil/DwarfLinker.cpp
index 0be12375b26..1e171db44c4 100644
--- a/llvm/tools/dsymutil/DwarfLinker.cpp
+++ b/llvm/tools/dsymutil/DwarfLinker.cpp
@@ -1206,6 +1206,7 @@ private:
     const char *Name, *MangledName;         ///< Names.
     uint32_t NameOffset, MangledNameOffset; ///< Offsets in the string pool.
 
+    uint64_t OrigLowPc;  ///< Value of AT_low_pc in the input DIE
     uint64_t OrigHighPc; ///< Value of AT_high_pc in the input DIE
     int64_t PCOffset;    ///< Offset to apply to PC addresses inside a function.
 
@@ -1214,8 +1215,8 @@ private:
 
     AttributesInfo()
         : Name(nullptr), MangledName(nullptr), NameOffset(0),
-          MangledNameOffset(0), OrigHighPc(0), PCOffset(0), HasLowPc(false),
-          IsDeclaration(false) {}
+          MangledNameOffset(0), OrigLowPc(UINT64_MAX), OrigHighPc(0),
+          PCOffset(0), HasLowPc(false), IsDeclaration(false) {}
   };
 
   /// \brief Helper for cloneDIE.
@@ -2274,7 +2275,12 @@ unsigned DwarfLinker::cloneAddressAttribute(DIE &Die, AttributeSpec AttrSpec,
   if (AttrSpec.Attr == dwarf::DW_AT_low_pc) {
     if (Die.getTag() == dwarf::DW_TAG_inlined_subroutine ||
         Die.getTag() == dwarf::DW_TAG_lexical_block)
-      Addr += Info.PCOffset;
+      // The low_pc of a block or inline subroutine might get
+      // relocated because it happens to match the low_pc of the
+      // enclosing subprogram. To prevent issues with that, always use
+      // the low_pc from the input DIE if relocations have been applied.
+      Addr = (Info.OrigLowPc != UINT64_MAX ? Info.OrigLowPc : Addr) +
+             Info.PCOffset;
     else if (Die.getTag() == dwarf::DW_TAG_compile_unit) {
       Addr = Unit.getLowPc();
       if (Addr == UINT64_MAX)
@@ -2522,6 +2528,11 @@ DIE *DwarfLinker::cloneDIE(const DWARFDebugInfoEntryMinimal &InputDIE,
     // high_pc value is done in cloneAddressAttribute().
     AttrInfo.OrigHighPc =
         InputDIE.getAttributeValueAsAddress(&U, dwarf::DW_AT_high_pc, 0);
+    // Also store the low_pc. It might get relocated in an
+    // inline_subprogram that happens at the beginning of its
+    // inlining function.
+    AttrInfo.OrigLowPc =
+        InputDIE.getAttributeValueAsAddress(&U, dwarf::DW_AT_low_pc, UINT64_MAX);
   }
 
   // Reset the Offset to 0 as we will be working on the local copy of