[llvm] r221835 - Allow DWARFFormValue::extractValue to be called with a null CU.

[Frederic Riss]

Author: friss
Date: Wed Nov 12 17:48:04 2014
New Revision: 221835

URL: http://llvm.org/viewvc/llvm-project?rev=221835&view=rev
Log:
Allow DWARFFormValue::extractValue to be called with a null CU.

Currently FormValues are only used for attributes of DIEs and thus
uers always have a CU lying around when calling into the FormValue
API.
Accelerator tables encode their information using the same Forms
as the attributes, thus it is natural to use DWARFFormValue to
extract/dump them. There is no CU in that case though. Allow the
API to be called with a null CU arguemnt by making the RelocMap
lookup conditional on the CU pointer validity. And document this
new behvior in the header. (Test coverage for this use of the API
comes in the DwarfAccelTable support patch)

Modified:
    llvm/trunk/include/llvm/DebugInfo/DWARFFormValue.h
    llvm/trunk/lib/DebugInfo/DWARFFormValue.cpp

Modified: llvm/trunk/include/llvm/DebugInfo/DWARFFormValue.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/DebugInfo/DWARFFormValue.h?rev=221835&r1=221834&r2=221835&view=diff
==============================================================================
--- llvm/trunk/include/llvm/DebugInfo/DWARFFormValue.h (original)
+++ llvm/trunk/include/llvm/DebugInfo/DWARFFormValue.h Wed Nov 12 17:48:04 2014
@@ -57,6 +57,13 @@ public:
   bool isFormClass(FormClass FC) const;
 
   void dump(raw_ostream &OS, const DWARFUnit *U) const;
+
+  /// \brief extracts a value in data at offset *offset_ptr.
+  ///
+  /// The passed DWARFUnit is allowed to be nullptr, in which
+  /// case no relocation processing will be performed and some
+  /// kind of forms that depend on Unit information are disallowed.
+  /// \returns wether the extraction succeeded.
   bool extractValue(DataExtractor data, uint32_t *offset_ptr,
                     const DWARFUnit *u);
   bool isInlinedCStr() const {

Modified: llvm/trunk/lib/DebugInfo/DWARFFormValue.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/DebugInfo/DWARFFormValue.cpp?rev=221835&r1=221834&r2=221835&view=diff
==============================================================================
--- llvm/trunk/lib/DebugInfo/DWARFFormValue.cpp (original)
+++ llvm/trunk/lib/DebugInfo/DWARFFormValue.cpp Wed Nov 12 17:48:04 2014
@@ -139,6 +139,8 @@ bool DWARFFormValue::extractValue(DataEx
     switch (Form) {
     case DW_FORM_addr:
     case DW_FORM_ref_addr: {
+      if (!cu)
+        return false;
       uint16_t AddrSize =
           (Form == DW_FORM_addr)
               ? cu->getAddressByteSize()
@@ -179,8 +181,10 @@ bool DWARFFormValue::extractValue(DataEx
       break;
     case DW_FORM_data4:
     case DW_FORM_ref4: {
-      RelocAddrMap::const_iterator AI = cu->getRelocMap()->find(*offset_ptr);
       Value.uval = data.getU32(offset_ptr);
+      if (!cu)
+        break;
+      RelocAddrMap::const_iterator AI = cu->getRelocMap()->find(*offset_ptr-4);
       if (AI != cu->getRelocMap()->end())
         Value.uval += AI->second.second;
       break;
@@ -193,13 +197,12 @@ bool DWARFFormValue::extractValue(DataEx
       Value.sval = data.getSLEB128(offset_ptr);
       break;
     case DW_FORM_strp: {
-      RelocAddrMap::const_iterator AI
-        = cu->getRelocMap()->find(*offset_ptr);
-      if (AI != cu->getRelocMap()->end()) {
-        const std::pair<uint8_t, int64_t> &R = AI->second;
-        Value.uval = data.getU32(offset_ptr) + R.second;
-      } else
-        Value.uval = data.getU32(offset_ptr);
+      Value.uval = data.getU32(offset_ptr);
+      if (!cu)
+        break;
+      RelocAddrMap::const_iterator AI = cu->getRelocMap()->find(*offset_ptr-4);
+      if (AI != cu->getRelocMap()->end())
+        Value.uval += AI->second.second;
       break;
     }
     case DW_FORM_udata:
@@ -215,13 +218,12 @@ bool DWARFFormValue::extractValue(DataEx
       break;
     case DW_FORM_sec_offset: {
       // FIXME: This is 64-bit for DWARF64.
-      RelocAddrMap::const_iterator AI
-        = cu->getRelocMap()->find(*offset_ptr);
-      if (AI != cu->getRelocMap()->end()) {
-        const std::pair<uint8_t, int64_t> &R = AI->second;
-        Value.uval = data.getU32(offset_ptr) + R.second;
-      } else
-        Value.uval = data.getU32(offset_ptr);
+      Value.uval = data.getU32(offset_ptr);
+      if (!cu)
+        break;
+      RelocAddrMap::const_iterator AI = cu->getRelocMap()->find(*offset_ptr-4);
+      if (AI != cu->getRelocMap()->end())
+        Value.uval +=  AI->second.second;
       break;
     }
     case DW_FORM_flag_present: