[llvm-symbolizer] Print file/line for a PC even if there is no DIE describing it.

This is important for symbolizing executables with debug info in
unavailable .dwo files. Even if all DIE entries are missing, we can
still symbolize an address: function name can be fetched from symbol table,
and file/line info can be fetched from line table.

llvm-svn: 206665

llvm/lib/DebugInfo/DWARFContext.cpp

@@ -545,18 +545,32 @@ DILineInfoTable DWARFContext::getLineInfoForAddressRange(uint64_t Address,
 
 DIInliningInfo DWARFContext::getInliningInfoForAddress(uint64_t Address,
     DILineInfoSpecifier Specifier) {
+  DIInliningInfo InliningInfo;
+
   DWARFCompileUnit *CU = getCompileUnitForAddress(Address);
   if (!CU)
-    return DIInliningInfo();
+    return InliningInfo;
 
+  const DWARFLineTable *LineTable = nullptr;
+  const bool NeedsAbsoluteFilePath =
+      Specifier.needs(DILineInfoSpecifier::AbsoluteFilePath);
   const DWARFDebugInfoEntryInlinedChain &InlinedChain =
       CU->getInlinedChainForAddress(Address);
-  if (InlinedChain.DIEs.size() == 0)
+  if (InlinedChain.DIEs.size() == 0) {
-    return DIInliningInfo();
+    // If there is no DIE for address (e.g. it is in unavailable .dwo file),
+    // try to at least get file/line info from symbol table.
+    if (Specifier.needs(DILineInfoSpecifier::FileLineInfo)) {
+      DILineInfo Frame;
+      LineTable = getLineTableForCompileUnit(CU);
+      if (getFileLineInfoForCompileUnit(CU, LineTable, Address,
+                                        NeedsAbsoluteFilePath, Frame)) {
+        InliningInfo.addFrame(Frame);
+      }
+    }
+    return InliningInfo;
+  }
 
-  DIInliningInfo InliningInfo;
   uint32_t CallFile = 0, CallLine = 0, CallColumn = 0;
-  const DWARFLineTable *LineTable = nullptr;
   for (uint32_t i = 0, n = InlinedChain.DIEs.size(); i != n; i++) {
     const DWARFDebugInfoEntryMinimal &FunctionDIE = InlinedChain.DIEs[i];
     DILineInfo Frame;
@@ -566,16 +580,13 @@ DIInliningInfo DWARFContext::getInliningInfoForAddress(uint64_t Address,
         Frame.FunctionName = Name;
     }
     if (Specifier.needs(DILineInfoSpecifier::FileLineInfo)) {
-      const bool NeedsAbsoluteFilePath =
-          Specifier.needs(DILineInfoSpecifier::AbsoluteFilePath);
       if (i == 0) {
         // For the topmost frame, initialize the line table of this
         // compile unit and fetch file/line info from it.
         LineTable = getLineTableForCompileUnit(CU);
         // For the topmost routine, get file/line info from line table.
         getFileLineInfoForCompileUnit(CU, LineTable, Address,
-                                      NeedsAbsoluteFilePath,
+                                      NeedsAbsoluteFilePath, Frame);
-                                      Frame);
       } else {
         // Otherwise, use call file, call line and call column from
         // previous DIE in inlined chain.

llvm/test/DebugInfo/Inputs/llvm-symbolizer-dwo-test.cc

@@ -0,0 +1,18 @@
+int f(int a, int b) {
+  return a + b;
+}
+
+int g(int a) {
+  return a + 1;
+}
+
+
+int main() {
+  return f(2, g(2));
+}
+
+// Built with Clang 3.5.0:
+// $ mkdir -p /tmp/dbginfo
+// $ cp llvm-symbolizer-dwo-test.cc /tmp/dbginfo
+// $ cd /tmp/dbginfo
+// $ clang -gsplit-dwarf llvm-symbolizer-dwo-test.cc

llvm/test/DebugInfo/llvm-symbolizer.test

@@ -8,6 +8,7 @@ RUN: echo "\"%p/Inputs/dwarfdump-test3.elf-x86-64 space\" 0x633" >> %t.input
 RUN: echo "%p/Inputs/macho-universal 0x1f84" >> %t.input
 RUN: echo "%p/Inputs/macho-universal:i386 0x1f67" >> %t.input
 RUN: echo "%p/Inputs/macho-universal:x86_64 0x100000f05" >> %t.input
+RUN: echo "%p/Inputs/llvm-symbolizer-dwo-test 0x400514" >> %t.input
 
 RUN: llvm-symbolizer --functions --inlining --demangle=false \
 RUN:    --default-arch=i386 < %t.input | FileCheck %s
@@ -48,6 +49,9 @@ CHECK:      main
 CHECK:      _Z3inci
 CHECK:      _Z3inci
 
+CHECK: main
+CHECK-NEXT: llvm-symbolizer-dwo-test.cc:11
+
 RUN: echo "unexisting-file 0x1234" > %t.input2
 RUN: llvm-symbolizer < %t.input2