use make_absolute to prevent failures when DWOName is already an absolute path

Author: Jinjie-Huang

bolt/lib/Core/BinaryContext.cpp

@@ -1633,25 +1633,27 @@ void BinaryContext::preprocessDWODebugInfo() {
           DwarfUnit->getUnitDIE().find(
               {dwarf::DW_AT_dwo_name, dwarf::DW_AT_GNU_dwo_name}),
           "");
-      SmallString<16> AbsolutePath;
+      SmallString<16> AbsolutePath(DWOName);
+      std::string DWOCompDir = DwarfUnit->getCompilationDir();
       if (!opts::CompDirOverride.empty()) {
-        sys::path::append(AbsolutePath, opts::CompDirOverride);
-        sys::path::append(AbsolutePath, DWOName);
-      } else if (!sys::fs::exists(DwarfUnit->getCompilationDir()) &&
-                 sys::fs::exists(DWOName)) {
+        DWOCompDir = opts::CompDirOverride;
+      } else if (!sys::fs::exists(DWOCompDir) && sys::fs::exists(DWOName)) {
+        DWOCompDir = ".";
         this->outs()
             << "BOLT-WARNING: Debug Fission: Debug Compilation Dir wrong for "
-            << DWOName << ". DWO Name will be directly used for retrieving.\n";
-        AbsolutePath = DWOName;
+            << DWOName << ". Relative path will be used for retrieving.\n";
       }
+      // Prevent failures when DWOName is already an absolute path.
+      sys::fs::make_absolute(DWOCompDir, AbsolutePath);
       DWARFUnit *DWOCU =
           DwarfUnit->getNonSkeletonUnitDIE(false, AbsolutePath).getDwarfUnit();
       if (!DWOCU->isDWOUnit()) {
         this->outs()
             << "BOLT-WARNING: Debug Fission: DWO debug information for "
             << DWOName
             << " was not retrieved and won't be updated. Please check "
-               "relative path.\n";
+               "relative path or use '--comp-dir-override' to specify the base "
+               "location.\n";
         continue;
       }
       DWOCUs[*DWOId] = DWOCU;

bolt/lib/Rewrite/DWARFRewriter.cpp

@@ -1846,17 +1846,16 @@ void DWARFRewriter::writeDWOFiles(
   }
 
   std::string CompDir = CU.getCompilationDir();
+  SmallString<16> AbsolutePath(DWOName);
 
   if (!opts::DwarfOutputPath.empty())
     CompDir = opts::DwarfOutputPath.c_str();
   else if (!opts::CompDirOverride.empty())
     CompDir = opts::CompDirOverride;
-  else if (!sys::fs::exists(CompDir) && sys::fs::exists(DWOName))
-    CompDir = "";
-
-  SmallString<16> AbsolutePath;
-  sys::path::append(AbsolutePath, CompDir);
-  sys::path::append(AbsolutePath, DWOName);
+  else if (!sys::fs::exists(CompDir))
+    CompDir = ".";
+  // Prevent failures when DWOName is already an absolute path.
+  sys::fs::make_absolute(CompDir, AbsolutePath);
 
   std::error_code EC;
   std::unique_ptr<ToolOutputFile> TempOut =

bolt/test/dwo-name-retrieving.c

@@ -2,16 +2,12 @@
 ## if the Debug Compilation Dir does not exist.
 
 # RUN: rm -rf %t && mkdir -p %t && cd %t
-# RUN: %clang %cflags -g -gsplit-dwarf  \
-# RUN:   -fdebug-compilation-dir=/path/does/not/exist %p/Inputs/hello.c -o main.exe
-# RUN: llvm-bolt %t/main.exe -o %t/main.exe.bolt -update-debug-sections \
-# RUN:   2>&1 | FileCheck %s -check-prefix=DWO-NAME
-# RUN: %clang %cflags -g -gsplit-dwarf  \
-# RUN:   -fdebug-compilation-dir=/path/does/not/exist %p/Inputs/hello.c -o %t/main.exe
-# RUN: llvm-bolt %t/main.exe -o %t/main.exe.bolt -update-debug-sections \
-# RUN:   2>&1 | FileCheck %s -check-prefix=DWO-NAME
+# RUN: %clang %cflags -g -gsplit-dwarf -fdebug-compilation-dir=/path/does/not/exist %p/Inputs/hello.c -o main.exe
+# RUN: llvm-bolt %t/main.exe -o %t/main.exe.bolt -update-debug-sections 2>&1 | FileCheck %s -check-prefix=DWO-NAME
+# RUN: %clang %cflags -g -gsplit-dwarf -fdebug-compilation-dir=/path/does/not/exist %p/Inputs/hello.c -o %t/main.exe
+# RUN: llvm-bolt %t/main.exe -o %t/main.exe.bolt -update-debug-sections 2>&1 | FileCheck %s -check-prefix=DWO-NAME
 
 # DWO-NAME: BOLT-WARNING: Debug Fission: Debug Compilation Dir wrong for
-# DWO-NAMET-NOT: Debug Fission: DWO debug information for/data00/home/huangjinjie/llvm-project/bolt/test/dwo-name-retrieving.test
-
+# DWO-NAMET-NOT: Debug Fission: DWO debug information for
+# DWO-NAMET-NOT: Assertion `FD >= 0 && "File not yet open!"' failed.