[SYCL] Fix ICE when -g and -ffile-prefix-map flags are set (#8459)

Set the source file name when footer is present and option
fmacro-prefix-map is used when generating debug information.

This patch is to fix a crash in the compiler when generating debug
information with the option -ffile-prefix-map.
Example:
$ pwd
/tmp/tmp.jocQk9WVa0
$
$ cat builtin.cpp 
void a(__builtin_va_list);
using ::a;
$
$ clang -c -g -fsycl /tmp/tmp.jocQk9WVa0/builtin.cpp
$ 
$ clang -g -fsycl -ffile-prefix-map=/tmp/=
/tmp/tmp.jocQk9WVa0/builtin.cpp
Expected<T> must be checked before access or destruction.
Unchecked Expected<T> contained error:
No such file or directoryPLEASE submit a bug report to
https://github.com/llvm/llvm-project/issues/ and include the crash
backtrace, preprocessed source, and associated run script.
Stack dump:
0.	Program arguments: 
…………………/tmp/tmp.jocQk9WVa0/builtin.cpp
1.	<eof> parser at end of file
2. /tmp/tmp.jocQk9WVa0/builtin.cpp:2:9: LLVM IR generation of
declaration 'a


https://github.com/intel/llvm/blob/sycl/clang/lib/CodeGen/CGDebugInfo.cpp#L397
is returning a error because the FileName is wrong.

Author: zahiraam

clang/lib/CodeGen/CGDebugInfo.cpp

@@ -392,8 +392,8 @@ std::optional<StringRef> CGDebugInfo::getSource(const SourceManager &SM,
 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);
+  llvm::Expected<FileEntryRef> ExpectedFileRef =
+      SM.getFileManager().getFileRef(FileName);
   if (ExpectedFileRef) {
     MainFileID = SM.getOrCreateFileID(ExpectedFileRef.get(),
                                       SrcMgr::CharacteristicKind::C_User);
@@ -407,18 +407,25 @@ llvm::DIFile *CGDebugInfo::getOrCreateFile(SourceLocation Loc) {
   FileID FID;
 
   if (Loc.isInvalid()) {
-    // The DIFile used by the CU is distinct from the main source file. Call
-    // createFile() below for canonicalization if the source file was specified
-    // with an absolute path.
-    FileName = TheCU->getFile()->getFilename();
+    if (CGM.getCodeGenOpts().SYCLUseMainFileName &&
+        CGM.getLangOpts().MacroPrefixMap.size() > 0) {
+      // When fmacro-prefix-map is used, the original source file
+      // file name is indicated by FullMainFileName instead of the CU.
+      auto &CGO = CGM.getCodeGenOpts();
+      FileName = CGO.FullMainFileName;
+      FID = ComputeValidFileID(SM, CGO.FullMainFileName);
+    } else {
+      // The DIFile used by the CU is distinct from the main source file. Call
+      // createFile() below for canonicalization if the source file was
+      // specified with an absolute path.
+      FileName = TheCU->getFile()->getFilename();
+    }
   } else {
     PresumedLoc PLoc = SM.getPresumedLoc(Loc);
     FileName = PLoc.getFilename();
 
     if (FileName.empty()) {
       FileName = TheCU->getFile()->getFilename();
-    } else {
-      FileName = PLoc.getFilename();
     }
     FID = PLoc.getFileID();
   }
@@ -654,11 +661,18 @@ void CGDebugInfo::CreateCompileUnit() {
   // file. Its directory part specifies what becomes the
   // DW_AT_comp_dir (the compilation directory), even if the source
   // file was specified with an absolute path.
+  // Unless an integration footer is involved, and the directory part is
+  // specified by the FileEntryRef provided by the FileID of the main source
+  // file.
   if (CSKind)
     CSInfo.emplace(*CSKind, Checksum);
-  llvm::DIFile *CUFile = DBuilder.createFile(
-      remapDIPath(MainFileName), remapDIPath(getCurrentDirname()), CSInfo,
-      getSource(SM, SM.getMainFileID()));
+
+  if (!CGM.getCodeGenOpts().SYCLUseMainFileName)
+    MainFileDir = getCurrentDirname();
+
+  llvm::DIFile *CUFile =
+      DBuilder.createFile(remapDIPath(MainFileName), remapDIPath(MainFileDir),
+                          CSInfo, getSource(SM, SM.getMainFileID()));
 
   StringRef Sysroot, SDK;
   if (CGM.getCodeGenOpts().getDebuggerTuning() == llvm::DebuggerKind::LLDB) {

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

@@ -24,6 +24,7 @@
 //
 // CHECK: !DICompileUnit({{.*}} file: ![[#FILE:]]
 // CHECK: ![[#FILE]] = !DIFile(filename: "{{.*}}clang{{.+}}test{{.+}}CodeGenSYCL{{.+}}Inputs{{.+}}debug-info-checksum.cpp"
+// CHECK-SAME: directory: "{{.*}}clang{{.+}}test{{.+}}CodeGenSYCL{{.+}}Inputs"
 // CHECK-SAME: checksumkind: CSK_MD5, checksum: "f1fb5d68350b47d90a53968ac8c40529"
 
 #include "Inputs/debug-info-checksum.cpp"

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

@@ -25,11 +25,13 @@
 // RUN: | FileCheck %s -check-prefix=COMP2
 
 // COMP1: !DICompileUnit({{.*}} file: ![[#FILE1:]]
-// COMP1: ![[#FILE1]] = !DIFile(filename: "{{.*}}clang{{.+}}test{{.+}}CodeGenSYCL{{.+}}checksum.cpp"
+// COMP1: ![[#FILE1]] = !DIFile(filename: "{{.*}}clang{{.+}}test{{.+}}CodeGenSYCL{{.+}}Inputs{{.+}}checksum.cpp"
+// COMP1-SAME: directory: "{{.*}}clang{{.+}}test{{.+}}CodeGenSYCL/Inputs"
 // COMP1-SAME: checksumkind: CSK_MD5, checksum: "259269f735d83ec32c46a11352458493")
 
 // COMP2: !DICompileUnit({{.*}} file: ![[#FILE2:]]
-// COMP2: ![[#FILE2]] = !DIFile(filename: "{{.*}}clang{{.+}}test{{.+}}CodeGenSYCL{{.+}}checksum.cpp"
+// COMP2: ![[#FILE2]] = !DIFile(filename: "{{.*}}clang{{.+}}test{{.+}}CodeGenSYCL{{.+}}Inputs{{.+}}checksum.cpp"
+// COMP2: directory: "{{.*}}clang{{.+}}test{{.+}}CodeGenSYCL/Output"
 // COMP2-SAME: checksumkind: CSK_MD5, checksum: "259269f735d83ec32c46a11352458493")
 
 // TODO: Fails on windows because of the use of append-file command that returns

clang/test/CodeGenSYCL/debug-info-file-prefix-map.cpp

@@ -0,0 +1,22 @@
+// This test checks that in the presence of the option -fdebug-prefix-map
+// the DICompileUnit information is correct, i.e  test filename and directory
+// path are correct.
+
+// 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 -fsycl-use-main-file-name \
+// RUN: -full-main-file-name %s \
+// RUN: -fmacro-prefix-map=%S/= -fcoverage-prefix-map=%S/= \
+// RUN: -fdebug-prefix-map=%S/= \
+// RUN: -debug-info-kind=constructor -emit-llvm -O0 -o - %s \
+// RUN: | FileCheck %s
+
+
+// CHECK: distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: ![[#FILE1:]]
+// CHECK-NEXT: ![[#FILE1]] = !DIFile(filename: "debug-info-file-prefix-map.cpp"
+// CHECK-SAME: directory: "{{.*}}clang{{.+}}test{{.+}}CodeGenSYCL"
+// CHECK: ![[#FILE2:]] = !DIFile(filename: "debug-info-file-prefix-map.cpp", directory: "")
+// CHECK: !DIDerivedType(tag: DW_TAG_typedef, name: "__builtin_va_list", file: ![[#FILE2]]
+
+void a(__builtin_va_list);
+using ::a;