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

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-debuginfo

Author: David Blaikie (dwblaikie)

<details>
<summary>Changes</summary>

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.


---
Full diff: https://github.com/llvm/llvm-project/pull/124846.diff


4 Files Affected:

- (modified) llvm/lib/DebugInfo/DWARF/DWARFContext.cpp (+1-1) 
- (modified) llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp (+2-1) 
- (modified) llvm/test/tools/llvm-symbolizer/skip-line-zero.s (+2-2) 
- (modified) llvm/test/tools/llvm-symbolizer/sym-verbose.test (+2-3) 


``````````diff
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp b/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
index 99e1642ff23ad5..15eac10688f18f 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
+++ b/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)
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp b/llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp
index 939a5163d55abc..a30ae163fa5a98 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp
+++ b/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;
diff --git a/llvm/test/tools/llvm-symbolizer/skip-line-zero.s b/llvm/test/tools/llvm-symbolizer/skip-line-zero.s
index e9fbea558e0eb8..74dfb5cdc1aaea 100644
--- a/llvm/test/tools/llvm-symbolizer/skip-line-zero.s
+++ b/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
diff --git a/llvm/test/tools/llvm-symbolizer/sym-verbose.test b/llvm/test/tools/llvm-symbolizer/sym-verbose.test
index 831fd6c7f05071..224c317f558a1a 100644
--- a/llvm/test/tools/llvm-symbolizer/sym-verbose.test
+++ b/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

``````````

</details>


https://github.com/llvm/llvm-project/pull/124846