[SYCL] Fix debug info generation when integration footer is present (#6774)

This patch is to fix two known issues with debugging caused by
integration footer presence, without redesigning the integration footer
approach.
One issue is the missing checksum for the main file on Windows. This
causes the breakpoints not being hit.
The other issue being that the host compilation's DICompileUnit points
to the temporary
file created instead of the original source file. So file names and
checksums are different for host and compilation.

The changes made to fix the issues are:
1. Driver passes an absolute path to an original source file through
-main-file-name if integration footer is enabled.
2. Driver passes a full path to the original source file through
-full-main-file-name.
3. Clang CodeGen uses the file specified through -main-file-name and
full-main-file-name to calculate checksums and file names for the main
file.

Joint work with @AlexeySachkov

Signed-off-by: Zahira Ammarguellat <[email protected]>

Author: zahiraam

clang/include/clang/Basic/CodeGenOptions.def

@@ -488,6 +488,10 @@ CODEGENOPT(SkipRaxSetup, 1, 0)
 ENUM_CODEGENOPT(ZeroCallUsedRegs, llvm::ZeroCallUsedRegs::ZeroCallUsedRegsKind,
                 5, llvm::ZeroCallUsedRegs::ZeroCallUsedRegsKind::Skip)
 
+/// Whether to expect -main-file-name to be an absolute path to use it for
+/// checksum calculations or not.
+CODEGENOPT(SYCLUseMainFileName, 1, 0)
+
 /// Whether to use opaque pointers.
 CODEGENOPT(OpaquePointers, 1, 0)
 

clang/include/clang/Basic/CodeGenOptions.h

@@ -220,6 +220,9 @@ class CodeGenOptions : public CodeGenOptionsBase {
   /// file, for example with -save-temps.
   std::string MainFileName;
 
+  /// The user provided name for the "main file", with its full path.
+  std::string FullMainFileName;
+
   /// The name for the split debug info file used for the DW_AT_[GNU_]dwo_name
   /// attribute in the skeleton CU.
   std::string SplitDwarfFile;

clang/include/clang/Driver/Options.td

@@ -6156,6 +6156,10 @@ def main_file_name : Separate<["-"], "main-file-name">,
   HelpText<"Main file name to use for debug info and source if missing">,
   Flags<[CC1Option, CC1AsOption, NoDriverOption]>,
   MarshallingInfoString<CodeGenOpts<"MainFileName">>;
+def full_main_file_name : Separate<["-"], "full-main-file-name">,
+  HelpText<"File name with full path to use for debug info during host and device compile">,
+  Flags<[CC1Option, CC1AsOption, NoDriverOption]>,
+  MarshallingInfoString<CodeGenOpts<"FullMainFileName">>;
 def split_dwarf_output : Separate<["-"], "split-dwarf-output">,
   HelpText<"File name to use for split dwarf debug info output">,
   Flags<[CC1Option, CC1AsOption, NoDriverOption]>,
@@ -6517,6 +6521,10 @@ def fsycl_disable_range_rounding : Flag<["-"], "fsycl-disable-range-rounding">,
 def fsycl_enable_int_header_diags: Flag<["-"], "fsycl-enable-int-header-diags">,
   HelpText<"Enable diagnostics that require the SYCL integration header.">,
   MarshallingInfoFlag<LangOpts<"SYCLEnableIntHeaderDiags">>;
+def fsycl_use_main_file_name : Flag<["-"], "fsycl-use-main-file-name">,
+  HelpText<"Tells compiler that -main-file-name contains an absolute path and "
+           "file specified there should be used for checksum calculation.">,
+  MarshallingInfoFlag<CodeGenOpts<"SYCLUseMainFileName">>;
 
 } // let Flags = [CC1Option, NoDriverOption]
 

clang/lib/CodeGen/CGDebugInfo.cpp

@@ -376,6 +376,19 @@ Optional<StringRef> CGDebugInfo::getSource(const SourceManager &SM,
   return Source;
 }
 
+// Compute valid FID for FileName.
+FileID ComputeValidFileID(SourceManager &SM, StringRef FileName) {
+  FileID MainFileID = SM.getMainFileID();
+  // Find the filename FileName and load it.
+  llvm::Expected<FileEntryRef>  ExpectedFileRef =
+    SM.getFileManager().getFileRef(FileName);
+  if (ExpectedFileRef) {
+    MainFileID = SM.getOrCreateFileID(ExpectedFileRef.get(),
+                                      SrcMgr::CharacteristicKind::C_User);
+  }
+  return MainFileID;
+}
+
 llvm::DIFile *CGDebugInfo::getOrCreateFile(SourceLocation Loc) {
   SourceManager &SM = CGM.getContext().getSourceManager();
   StringRef FileName;
@@ -408,6 +421,13 @@ llvm::DIFile *CGDebugInfo::getOrCreateFile(SourceLocation Loc) {
 
   SmallString<32> Checksum;
 
+  if (SM.getFileEntryForID(SM.getMainFileID()) &&
+      CGM.getCodeGenOpts().SYCLUseMainFileName && FID.isInvalid())
+    // When an integration footer is involved, the main file is a temporary
+    // file generated by the compiler. FileName is pointing to original user
+    // source file. We use it here to properly calculate its checksum.
+    FID = ComputeValidFileID(SM, FileName);
+
   Optional<llvm::DIFile::ChecksumKind> CSKind = computeChecksum(FID, Checksum);
   Optional<llvm::DIFile::ChecksumInfo<StringRef>> CSInfo;
   if (CSKind)
@@ -514,22 +534,37 @@ void CGDebugInfo::CreateCompileUnit() {
   // Get absolute path name.
   SourceManager &SM = CGM.getContext().getSourceManager();
   std::string MainFileName = CGM.getCodeGenOpts().MainFileName;
+  std::string FullMainFileName = CGM.getCodeGenOpts().FullMainFileName;
   if (MainFileName.empty())
     MainFileName = "<stdin>";
 
   // The main file name provided via the "-main-file-name" option contains just
   // the file name itself with no path information. This file name may have had
   // a relative path, so we look into the actual file entry for the main
   // file to determine the real absolute path for the file.
+  // An exception here is workflow when integration footer is involved: in that
+  // case driver passes an absolute path to the original user-provided source
+  // file, whilst main file corresponds to a temporary file generated by the
+  // compiler.
   std::string MainFileDir;
   if (Optional<FileEntryRef> MainFile =
           SM.getFileEntryRefForID(SM.getMainFileID())) {
     MainFileDir = std::string(MainFile->getDir().getName());
-    if (!llvm::sys::path::is_absolute(MainFileName)) {
+    FileID MainFileID = SM.getMainFileID();
+    if (!llvm::sys::path::is_absolute(MainFileName) &&
+        !CGM.getCodeGenOpts().SYCLUseMainFileName) {
       llvm::SmallString<1024> MainFileDirSS(MainFileDir);
       llvm::sys::path::append(MainFileDirSS, MainFileName);
       MainFileName =
           std::string(llvm::sys::path::remove_leading_dotslash(MainFileDirSS));
+    } else if (CGM.getCodeGenOpts().SYCLUseMainFileName) {
+      // When an integration footer is involved, the main file is a temporary
+      // file generated by the compiler. FullMainFileName is pointing to
+      // original user source file. We use it here to properly calculate its
+      // checksum.
+      MainFileID = ComputeValidFileID(SM, FullMainFileName);
+      // Make sure the filename points to the original user source filename.
+      MainFileName = FullMainFileName;
     }
     // If the main file name provided is identical to the input file name, and
     // if the input file is a preprocessed source, use the module name for
@@ -541,7 +576,7 @@ void CGDebugInfo::CreateCompileUnit() {
             .isPreprocessed())
       MainFileName = CGM.getModule().getName().str();
 
-    CSKind = computeChecksum(SM.getMainFileID(), Checksum);
+    CSKind = computeChecksum(MainFileID, Checksum);
   }
 
   llvm::dwarf::SourceLanguage LangTag;

clang/lib/Driver/ToolChains/Clang.cpp

@@ -5449,8 +5449,20 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   // Set the main file name, so that debug info works even with
   // -save-temps.
   CmdArgs.push_back("-main-file-name");
-  CmdArgs.push_back(getBaseInputName(Args, Input));
+  if (!IsSYCL || Args.hasArg(options::OPT_fno_sycl_use_footer)) {
+    CmdArgs.push_back(getBaseInputName(Args, Input));
+  } else {
+    SmallString<256> AbsPath = llvm::StringRef(Input.getBaseInput());
+    D.getVFS().makeAbsolute(AbsPath);
+    CmdArgs.push_back(
+        Args.MakeArgString(llvm::sys::path::filename(Input.getBaseInput())));
+    CmdArgs.push_back("-fsycl-use-main-file-name");
+  }
 
+  if (IsSYCL || Args.hasArg(options::OPT_fsycl_footer_path_EQ)) {
+    CmdArgs.push_back("-full-main-file-name");
+    CmdArgs.push_back(Input.getBaseInput());
+  }
   // Some flags which affect the language (via preprocessor
   // defines).
   if (Args.hasArg(options::OPT_static))

clang/test/CodeGenSYCL/Inputs/checksum.cpp

@@ -0,0 +1,4 @@
+int main() {
+  int x = 0;
+  return x + 1;
+}

clang/test/CodeGenSYCL/Inputs/debug-info-checksum.cpp

@@ -0,0 +1,9 @@
+#include "Inputs/sycl.hpp"
+
+int main() {
+  sycl::sampler Sampler;
+  sycl::kernel_single_task<class use_kernel_for_test>([=]() {
+    Sampler.use();
+  });
+  return 0;
+}

clang/test/CodeGenSYCL/debug-info-checksum-temp-name.cpp

@@ -0,0 +1,29 @@
+// This file attempts to emulate content of a file, which is passed to host
+// compiler when integration footer is used: this file is considered to be a
+// main file and Inputs/debug-info-checksum.cpp serves as integration footer.
+//
+// The file is specifically named debug-info-checksum-temp-name.cpp to emulate
+// the temporary file name, which is generated by the compiler driver for the
+// host .cpp file after appending footer to it.
+//
+// The command line executed is based on what is actually invoked by the
+// compiler driver and we explicitly pass 'Inputs/debug-info-checksum.cpp' as
+// a main file name to ensure that we can instruct the compiler to emit the
+// correct debug info (paths and checksums), even though the input file is not
+// exactly what user specified on the command line.
+//
+// RUN: %clang_cc1 -fsycl-is-host -I %S %S/Inputs/debug-info-checksum.cpp \
+// RUN:   -triple x86_64-unknown-linux-gpu \
+// RUN:   -main-file-name "%S/Inputs/debug-info-checksum.cpp" \
+// RUN:   -full-main-file-name "%S/Inputs/debug-info-checksum.cpp" \
+// RUN:   -fsycl-use-main-file-name -dwarf-version=5 -S -emit-llvm \
+// RUN:   -O0 -debug-info-kind=constructor -o - | FileCheck %s
+//
+// Verify that DICompileUnit points to a correct file and that checksum is also
+// correct.
+//
+// CHECK: !DICompileUnit({{.*}} file: ![[#FILE:]]
+// CHECK: ![[#FILE]] = !DIFile(filename: "{{.*}}clang{{.+}}test{{.+}}CodeGenSYCL{{.+}}Inputs{{.+}}debug-info-checksum.cpp"
+// CHECK-SAME: checksumkind: CSK_MD5, checksum: "f1fb5d68350b47d90a53968ac8c40529"
+
+#include "Inputs/debug-info-checksum.cpp"

clang/test/CodeGenSYCL/debug-info-file-checksum.cpp

@@ -0,0 +1,33 @@
+// This test checks that a checksum is created correctly for the compiled file,
+// and that the same checksum is generated for host and target compilation.
+// It also checks that DICompileUnit in host and target compilation is referring
+// to the original source file name (not the temporary file created by the
+// compilation process) .
+
+// RUN: %clang_cc1 -triple spir64-unknown-unknown -fsycl-is-device \
+// RUN: -fsycl-int-header=%t.header.h -fsycl-int-footer=%t.footer.h \
+// RUN: -main-file-name %S/Inputs/checksum.cpp -fsycl-use-main-file-name \
+// RUN: -full-main-file-name "%S/Inputs/checksum.cpp" \
+// RUN: -gcodeview -debug-info-kind=limited -emit-llvm -O0 -o - "%S/Inputs/checksum.cpp" \
+// RUN: | FileCheck %s -check-prefix=COMP1
+
+// RUN: append-file "%S/Inputs/checksum.cpp" \
+// RUN: --append=%t.footer.h \
+// RUN: --orig-filename="%S/Inputs/checksum.cpp" \
+// RUN: --output=%t.checksum.cpp --use-include
+
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fsycl-is-host \
+// RUN: -include %t.header.h -dependency-filter %t.header.h \
+// RUN: -main-file-name %S/Inputs/checksum.cpp -fsycl-use-main-file-name \
+// RUN: -full-main-file-name %S/Inputs/checksum.cpp \
+// RUN: -gcodeview -debug-info-kind=limited -emit-llvm -O0 -o - \
+// RUN: %t.checksum.cpp \
+// RUN: | FileCheck %s -check-prefix=COMP2
+
+// COMP1: !DICompileUnit({{.*}} file: ![[#FILE1:]]
+// COMP1: ![[#FILE1]] = !DIFile(filename: "{{.*}}clang{{.+}}test{{.+}}CodeGenSYCL{{.+}}checksum.cpp"
+// COMP1-SAME: checksumkind: CSK_MD5, checksum: "259269f735d83ec32c46a11352458493")
+
+// COMP2: !DICompileUnit({{.*}} file: ![[#FILE2:]]
+// COMP2: ![[#FILE2]] = !DIFile(filename: "{{.*}}clang{{.+}}test{{.+}}CodeGenSYCL{{.+}}checksum.cpp"
+// COMP2-SAME: checksumkind: CSK_MD5, checksum: "259269f735d83ec32c46a11352458493")

clang/test/Driver/sycl-int-footer.cpp

@@ -3,7 +3,7 @@
 // RUN:   | FileCheck -check-prefix FOOTER %s -DSRCDIR=%/S -DCMDDIR=cmdline/dir
 // FOOTER: clang{{.*}} "-fsycl-is-device"{{.*}} "-fsycl-int-header=[[INTHEADER:.+\.h]]" "-fsycl-int-footer=[[INTFOOTER:.+\h]]" "-sycl-std={{.*}}"{{.*}} "-include" "dummy.h"
 // FOOTER: append-file{{.*}} "[[INPUTFILE:.+\.cpp]]" "--append=[[INTFOOTER]]" "--orig-filename=[[INPUTFILE]]" "--output=[[APPENDEDSRC:.+\.cpp]]"
-// FOOTER: clang{{.*}} "-include" "[[INTHEADER]]"{{.*}} "-fsycl-is-host"{{.*}} "-include" "dummy.h"{{.*}} "-iquote" "[[SRCDIR]]" "-I" "cmdline/dir"
+// FOOTER: clang{{.*}} "-include" "[[INTHEADER]]"{{.*}} "-fsycl-is-host"{{.*}} "-main-file-name" "[[SRCFILE:.+\cpp]]" "-fsycl-use-main-file-name{{.*}} "-include" "dummy.h"{{.*}} "-iquote" "[[SRCDIR]]" "-I" "cmdline/dir"
 // FOOTER-NOT: "-include" "[[INTHEADER]]"
 
 /// Preprocessed file creation with integration footer
@@ -24,9 +24,15 @@
 
 /// Check that integration footer can be disabled
 // RUN:  %clangxx -fsycl -fno-sycl-use-footer %s -### 2>&1 \
-// RUN:   | FileCheck -check-prefix NO-FOOTER --implicit-check-not "-fsycl-int-footer" %s
+// RUN:   | FileCheck -check-prefix NO-FOOTER --implicit-check-not "-fsycl-int-footer" --implicit-check-not "-fsycl-use-main-file-name" %s
 // NO-FOOTER: clang{{.*}} "-fsycl-is-device"{{.*}} "-fsycl-int-header=[[INTHEADER:.+\.h]]" "-sycl-std={{.*}}"
-// NO-FOOTER: clang{{.*}} "-include" "[[INTHEADER]]"{{.*}} "-fsycl-is-host"{{.*}} "-o"
+// NO-FOOTER: clang{{.*}} "-include" "[[INTHEADER]]"{{.*}} "-fsycl-is-host"{{.*}} "-main-file-name" "sycl-int-footer.cpp"{{.*}} "-o"
+
+// Test that -fsycl-use-main-file-name is not passed if -fsycl is not passed.
+// This test is located here, because -fsycl-use-main-file-name is tightly
+// connected to the integration footer.
+// RUN: %clangxx %s -### 2>&1 | FileCheck %s --check-prefix NO-FSYCL --implicit-check-not "-fsycl-use-main-file-name"
+// NO-FSYCL: clang{{.*}} "-main-file-name" "sycl-int-footer.cpp"
 
 /// Check phases without integration footer
 // RUN: %clangxx -fsycl -fno-sycl-instrument-device-code -fno-sycl-device-lib=all -fno-sycl-use-footer -target x86_64-unknown-linux-gnu %s -ccc-print-phases 2>&1 \