DWARF: Put all the pieces we have together and provide a single accessor to DIContext that provides line information when given an address.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139836 91177308-0d34-0410-b5e6-96231b3b80d8

lib/DebugInfo/DWARFContext.cpp

@@ -11,6 +11,7 @@
 #include "llvm/Support/Dwarf.h"
 #include "llvm/Support/Format.h"
 #include "llvm/Support/raw_ostream.h"
+#include <algorithm>
 using namespace llvm;
 using namespace dwarf;
 
@@ -112,3 +113,51 @@ void DWARFContext::parseCompileUnits() {
     offset = CUs.back().getNextCompileUnitOffset();
   }
 }
+
+namespace {
+  struct OffsetComparator {
+    bool operator()(const DWARFCompileUnit &LHS,
+                    const DWARFCompileUnit &RHS) const {
+      return LHS.getOffset() < RHS.getOffset();
+    }
+    bool operator()(const DWARFCompileUnit &LHS, uint32_t RHS) const {
+      return LHS.getOffset() < RHS;
+    }
+    bool operator()(uint32_t LHS, const DWARFCompileUnit &RHS) const {
+      return LHS < RHS.getOffset();
+    }
+  };
+}
+
+DWARFCompileUnit *DWARFContext::getCompileUnitForOffset(uint32_t offset) {
+  if (CUs.empty())
+    parseCompileUnits();
+
+  DWARFCompileUnit *i = std::lower_bound(CUs.begin(), CUs.end(), offset,
+                                         OffsetComparator());
+  if (i != CUs.end())
+    return &*i;
+  return 0;
+}
+
+DILineInfo DWARFContext::getLineInfoForAddress(uint64_t address) {
+  // First, get the index for the arange.
+  uint32_t arangeIndex = getDebugAranges()->findAddress(address);
+  // From there, get the offset of the compile unit.
+  uint32_t cuOffset = getDebugAranges()->offsetAtIndex(arangeIndex);
+  // Retrieve the compile unit.
+  DWARFCompileUnit *cu = getCompileUnitForOffset(cuOffset);
+  // Get the line table for this compile unit.
+  const DWARFDebugLine::LineTable *lineTable = getLineTableForCompileUnit(cu);
+  // Get the index of the row we're looking for in the line table.
+  uint64_t hiPC =
+    cu->getCompileUnitDIE()->getAttributeValueAsUnsigned(cu, DW_AT_high_pc,
+                                                         -1ULL);
+  uint32_t rowIndex = lineTable->lookupAddress(address, hiPC);
+
+  // From here, contruct the DILineInfo.
+  const DWARFDebugLine::Row &row = lineTable->Rows[rowIndex];
+  const std::string &fileName = lineTable->Prologue.FileNames[row.File-1].Name;
+
+  return DILineInfo(fileName.c_str(), row.Line, row.Column);
+}