[llvm-gsymutil] Print one-time DWO file missing warning under --quiet flag

[kusmour]

FileCheck test added

./bin/llvm-lit -sv llvm/test/tools/llvm-gsymutil/X86/dwo-warning.test

Manual test steps:

• Create binary with split-dwarf:

clang++ -g -gdwarf-4 -gsplit-dwarf main.cpp -o main_split

• Remane the dwo file to a different name so llvm-gsymutil can't find it

mv main_split-main.dwo main_split-main__.dwo

• Now run llvm-gsymutil conversion, it should print out warning with and without the --quiet flag

$ ./bin/llvm-gsymutil --convert=./main_split
Input file: ./main_split
Output file (x86_64): ./main_split.gsym
warning: Unable to retrieve DWO .debug_info section for main_split-main.dwo
Loaded 0 functions from DWARF.
Loaded 12 functions from symbol table.
Pruned 0 functions, ended with 12 total

$ ./bin/llvm-gsymutil --convert=./main_split --quiet
Input file: ./main_split
Output file (x86_64): ./main_split.gsym
warning: Unable to retrieve DWO .debug_info section for some object files. (Remove the --quiet flag for full output)
Pruned 0 functions, ended with 12 total

[llvmbot]

@llvm/pr-subscribers-debuginfo

Author: kusmour (kusmour)

Changes

FileCheck test added

./bin/llvm-lit -sv llvm/test/tools/llvm-gsymutil/X86/dwo-warning.test

Manual test steps:

• Create binary with split-dwarf:

clang++ -g -gdwarf-4 -gsplit-dwarf main.cpp -o main_split

• Remane the dwo file to a different name so llvm-gsymutil can't find it

mv main_split-main.dwo main_split-main__.dwo

• Now run llvm-gsymutil conversion, it should print out warning with and without the --quiet flag

$ ./bin/llvm-gsymutil --convert=./main_split
Input file: ./main_split
Output file (x86_64): ./main_split.gsym
warning: Unable to retrieve DWO .debug_info section for main_split-main.dwo
Loaded 0 functions from DWARF.
Loaded 12 functions from symbol table.
Pruned 0 functions, ended with 12 total

$ ./bin/llvm-gsymutil --convert=./main_split --quiet
Input file: ./main_split
Output file (x86_64): ./main_split.gsym
warning: Unable to retrieve DWO .debug_info section for some object files. (Remove the --quiet flag for full output)
Pruned 0 functions, ended with 12 total

---

Full diff: https://github.com/llvm/llvm-project/pull/79882.diff

6 Files Affected:

• (modified) llvm/lib/DebugInfo/GSYM/DwarfTransformer.cpp (+17-7)
• (added) llvm/test/tools/llvm-gsymutil/X86/Inputs/main.cpp (+13)
• (added) llvm/test/tools/llvm-gsymutil/X86/Inputs/main_split ()
• (added) llvm/test/tools/llvm-gsymutil/X86/Inputs/main_split-main__.dwo ()
• (added) llvm/test/tools/llvm-gsymutil/X86/Inputs/main_split.gsym ()
• (added) llvm/test/tools/llvm-gsymutil/X86/dwo-warning.test (+32)

diff --git a/llvm/lib/DebugInfo/GSYM/DwarfTransformer.cpp b/llvm/lib/DebugInfo/GSYM/DwarfTransformer.cpp
index 0b225376349ece..6268c7845a142a 100644
--- a/llvm/lib/DebugInfo/GSYM/DwarfTransformer.cpp
+++ b/llvm/lib/DebugInfo/GSYM/DwarfTransformer.cpp
@@ -537,17 +537,27 @@ void DwarfTransformer::handleDie(raw_ostream *OS, CUInfo &CUI, DWARFDie Die) {
 
 Error DwarfTransformer::convert(uint32_t NumThreads, raw_ostream *OS) {
   size_t NumBefore = Gsym.getNumFunctionInfos();
+  std::once_flag flag;
   auto getDie = [&](DWARFUnit &DwarfUnit) -> DWARFDie {
     DWARFDie ReturnDie = DwarfUnit.getUnitDIE(false);
     if (DwarfUnit.getDWOId()) {
       DWARFUnit *DWOCU = DwarfUnit.getNonSkeletonUnitDIE(false).getDwarfUnit();
-      if (OS && !DWOCU->isDWOUnit()) {
-        std::string DWOName = dwarf::toString(
-            DwarfUnit.getUnitDIE().find(
-                {dwarf::DW_AT_dwo_name, dwarf::DW_AT_GNU_dwo_name}),
-            "");
-        *OS << "warning: Unable to retrieve DWO .debug_info section for "
-            << DWOName << "\n";
+      if (!DWOCU->isDWOUnit()) {
+        if (OS) {
+          std::string DWOName = dwarf::toString(
+              DwarfUnit.getUnitDIE().find(
+                  {dwarf::DW_AT_dwo_name, dwarf::DW_AT_GNU_dwo_name}),
+              "");
+          *OS << "warning: Unable to retrieve DWO .debug_info section for "
+              << DWOName << "\n";
+        } else {
+          std::call_once(flag, []() {
+            outs()
+                << "warning: Unable to retrieve DWO .debug_info section for "
+                   "some "
+                   "object files. (Remove the --quiet flag for full output)\n";
+          });
+        }
       } else {
         ReturnDie = DWOCU->getUnitDIE(false);
       }
diff --git a/llvm/test/tools/llvm-gsymutil/X86/Inputs/main.cpp b/llvm/test/tools/llvm-gsymutil/X86/Inputs/main.cpp
new file mode 100644
index 00000000000000..4c72cdf16a232a
--- /dev/null
+++ b/llvm/test/tools/llvm-gsymutil/X86/Inputs/main.cpp
@@ -0,0 +1,13 @@
+#include <iostream>
+#include <unistd.h>
+
+void foo() {
+    std::cout << "This is foo" << std::endl;
+}
+
+int main() {
+    std::cout << "hello world" << std::endl;
+    foo();
+    std::cout << "after foo" << std::endl;
+    return 0;
+}
diff --git a/llvm/test/tools/llvm-gsymutil/X86/Inputs/main_split b/llvm/test/tools/llvm-gsymutil/X86/Inputs/main_split
new file mode 100755
index 00000000000000..a448f1bdf93b2b
Binary files /dev/null and b/llvm/test/tools/llvm-gsymutil/X86/Inputs/main_split differ
diff --git a/llvm/test/tools/llvm-gsymutil/X86/Inputs/main_split-main__.dwo b/llvm/test/tools/llvm-gsymutil/X86/Inputs/main_split-main__.dwo
new file mode 100644
index 00000000000000..4bb34ae7bd6bdf
Binary files /dev/null and b/llvm/test/tools/llvm-gsymutil/X86/Inputs/main_split-main__.dwo differ
diff --git a/llvm/test/tools/llvm-gsymutil/X86/Inputs/main_split.gsym b/llvm/test/tools/llvm-gsymutil/X86/Inputs/main_split.gsym
new file mode 100644
index 00000000000000..c9e074bb3568d8
Binary files /dev/null and b/llvm/test/tools/llvm-gsymutil/X86/Inputs/main_split.gsym differ
diff --git a/llvm/test/tools/llvm-gsymutil/X86/dwo-warning.test b/llvm/test/tools/llvm-gsymutil/X86/dwo-warning.test
new file mode 100644
index 00000000000000..0a57c8dfe8791d
--- /dev/null
+++ b/llvm/test/tools/llvm-gsymutil/X86/dwo-warning.test
@@ -0,0 +1,32 @@
+$ cat > main.cpp
+#include <iostream>
+#include <unistd.h>
+
+void foo() {
+    std::cout << "This is foo" << std::endl;
+}
+
+int main() {
+    std::cout << "hello world" << std::endl;
+    foo();
+    std::cout << "after foo" << std::endl;
+    return 0;
+}
+
+$ clang++ -g -gdwarf-4 -gsplit-dwarf main.cpp -o main_split
+$ mv main_split-main.dwo main_split-main__.dwo
+
+// RUN: llvm-gsymutil --convert=%p/Inputs/main_split | FileCheck %s --check-prefix=WARNING
+// RUN: llvm-gsymutil --convert=%p/Inputs/main_split --quiet 2>&1 | FileCheck %s --check-prefix=WARNING-QUIET
+
+// WARNING: Input file:  {{.*\/main_split}}
+// WARNING: Output file (x86_64): {{.*\.gsym}}
+// WARNING: warning: Unable to retrieve DWO .debug_info section for main_split-main.dwo
+// WARNING: Loaded 0 functions from DWARF.
+// WARNING: Loaded 12 functions from symbol table.
+// WARNING: Pruned 0 functions, ended with 12 total
+
+// WARNING-QUIET: Input file: {{.*\/main_split}}
+// WARNING-QUIET: Output file (x86_64): {{.*\.gsym}}
+// WARNING-QUIET: warning: Unable to retrieve DWO .debug_info section for some object files. (Remove the --quiet flag for full output)
+// WARNING-QUIET: Pruned 0 functions, ended with 12 total

[clayborg]

Very close, just one inline comment

[dwblaikie]

FWIW, these days we tend to avoid checking in binaries for testing these tools - instead checking in assembly and generating dwarf objects from that in the test with llvm-mc, or similar pipelines, where possible.

[ayermolo]

Looks like there is --verbose option. Maybe have the same path for default verbosity and no OS, and print all the files for higher verbosity?

[kusmour]

It seems the --verbose is only used for lookups. We will need to expose that option (the same way as --quiet) to Transformer level. If we want to go this path I will do it in a separate patch. Let's focus on the changing the --quiet behavior here :D

[ayermolo]

+1 on assembly. bolt/test/X86 has bunch of examples.

[clayborg]

LGTM