Symbolize line zero as if no source info is available (llvm#124846)

Since line zero means "no line information", when symbolizing a location
(an address or an inline frame associated with the address) that has a
line zero location, we shouldn't include other irrelevant data (like
filename) in the result.

Author: dwblaikie

llvm/lib/DebugInfo/DWARF/DWARFContext.cpp

@@ -1869,7 +1869,7 @@ DWARFContext::getInliningInfoForAddress(object::SectionedAddress Address,
           LineTable->getFileLineInfoForAddress(
               {Address.Address, Address.SectionIndex}, Spec.ApproximateLine,
               CU->getCompilationDir(), Spec.FLIKind, Frame);
-      } else {
+      } else if (CallLine != 0) {
         // Otherwise, use call file, call line and call column from
         // previous DIE in inlined chain.
         if (LineTable)

llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp

@@ -1508,7 +1508,8 @@ bool DWARFDebugLine::LineTable::getFileLineInfoForAddress(
     return false;
   // Take file number and line/column from the row.
   const auto &Row = Rows[RowIndex];
-  if (!getFileNameByIndex(Row.File, CompDir, Kind, Result.FileName))
+  if (Row.Line == 0 ||
+      !getFileNameByIndex(Row.File, CompDir, Kind, Result.FileName))
     return false;
   Result.Line = Row.Line;
   Result.Column = Row.Column;

llvm/test/tools/llvm-symbolizer/skip-line-zero.s

@@ -20,13 +20,13 @@
 ## Check that without '--skip-line-zero', line zero is displayed for a line-table entry which has no source correspondence.
 # RUN: llvm-symbolizer --obj=%t.o -f=none 0x16d4 | FileCheck --strict-whitespace --match-full-lines --check-prefix=DISABLE %s
 
-# DISABLE:main.c:0:0
+# DISABLE:??:0:0
 
 ## Check that the '--skip-line-zero' does not cross sequence boundaries.
 ## If it fails to find in the current sequence then line zero is returned for the queried address.
 # RUN: llvm-symbolizer --obj=%t.o -f=none --skip-line-zero 0x16c0 | FileCheck --strict-whitespace --match-full-lines --check-prefix=FAIL-ACROSS-SEQ %s
 
-# FAIL-ACROSS-SEQ:main.c:0:0
+# FAIL-ACROSS-SEQ:??:0:0
 
 ## Check that with '--skip-line-zero', the last non-zero line in the current sequence is displayed.
 # RUN: llvm-symbolizer --obj=%t.o -f=none --skip-line-zero 0x1717 | FileCheck --strict-whitespace --match-full-lines --check-prefix=WITHIN-SEQ %s

llvm/test/tools/llvm-symbolizer/sym-verbose.test

@@ -50,13 +50,12 @@ CHECK-NEXT: Column: 0
 
 CHECK: 0x4005ad
 CHECK-NEXT: foo
-CHECK-NEXT: Filename: /tmp{{[\\/]}}discrim.c
+CHECK-NEXT: Filename: ??
 CHECK-NEXT: Function start filename: /tmp{{[\\/]}}discrim.c
 CHECK-NEXT: Function start line: 4
 CHECK-NEXT: Function start address: 0x400590
 CHECK-NEXT: Line: 0
-CHECK-NEXT: Column: 30
-CHECK-NEXT: Discriminator: 4
+CHECK-NEXT: Column: 0
 CHECK-NEXT: main
 CHECK-NEXT: Filename: /tmp{{[\\/]}}discrim.c
 CHECK-NEXT: Function start filename: /tmp{{[\\/]}}discrim.c