[OpenMP][OMPIRBuilder] Use the source (=directory + filename) for locations

[lebedev.ri]

Thanks. Seems to fix the test for me FWIW, but

1. why wasn't this caught by anyone and all of the bots?
2. what is the actual underlying problem, if any?

[jdoerfert]

Something is fishy here. Now the pre-merge tests fail... this should accept strictly more... I have to look into this, best guess: some non-determinism

[hubert.reinterpretcast]

In D85938#2216905, @lebedev.ri wrote:

Thanks. Seems to fix the test for me FWIW, but

1. why wasn't this caught by anyone and all of the bots?

For what it's worth, I have been affected by this and was drafting a note to D82822 today to ask about the status.

2. what is the actual underlying problem, if any?

[jdoerfert]

Root cause:
We sometimes, depending on the invocation and potentially other factors, use a full path and sometimes not:
So wen I run this with clang locally I get this:

@98 = private unnamed_addr constant [98 x i8] c";/data/src/llvm-project/clang/test/OpenMP/irbuilder_nested_parallel_for.c;parallel_for_2;294;16;;\00", align 1                                                                                               
@100 = private unnamed_addr constant %struct.ident_t { i32 0, i32 2, i32 0, i32 0, i8* getelementptr inbounds ([98 x i8], [98 x i8]* @98, i32 0, i32 0) }, align 8
@101 = private unnamed_addr constant [92 x i8] c";src/llvm-project/clang/test/OpenMP/irbuilder_nested_parallel_for.c;parallel_for_2;294;16;;\00", align 1
@103 = private unnamed_addr constant %struct.ident_t { i32 0, i32 2, i32 0, i32 0, i8* getelementptr inbounds ([92 x i8], [92 x i8]* @101, i32 0, i32 0) }, align 8

Note the 6 missing characters /data/ in the second string. Because they are missing, we generate two globals for this. When I run the same test with the update script I get one global as they agree on the location.

Looking for the location that strips the path now.

[jdoerfert]

Resolve the root cause

[lebedev.ri]

still lg, i guess

clang/test/OpenMP/irbuilder_nested_parallel_for.c

258 ↗

(On Diff #285551)

Please precommit test regeneration first.

llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp

Constant *OpenMPIRBuilder::getOrCreateDefaultSrcLocStr() {
   return getOrCreateSrcLocStr(";unknown;unknown;0;0;;");
 }
 
 Constant *
 OpenMPIRBuilder::getOrCreateSrcLocStr(const LocationDescription &Loc) {
   DILocation *DIL = Loc.DL.get();
   if (!DIL)
     return getOrCreateDefaultSrcLocStr();
-  StringRef FileName =
-      !DIL->getFilename().empty() ? DIL->getFilename() : M.getName();
+  StringRef FileName = M.getName();
+  if (DIFile *DIF = DIL->getFile())
+    if (Optional<StringRef> Source = DIF->getSource())
+      FileName = *Source;
   StringRef Function = DIL->getScope()->getSubprogram()->getName();
   Function =
       !Function.empty() ? Function : Loc.IP.getBlock()->getParent()->getName();
   return getOrCreateSrcLocStr(Function, FileName, DIL->getLine(),
                               DIL->getColumn());
 }
 
 Value *OpenMPIRBuilder::getOrCreateThreadID(Value *Ident) {

llvm/unittests/Frontend/OpenMPIRBuilderTest.cpp

void SetUp() override {
     M.reset(new Module("MyModule", Ctx));
     FunctionType *FTy =
         FunctionType::get(Type::getVoidTy(Ctx), {Type::getInt32Ty(Ctx)},
                           /*isVarArg=*/false);
     F = Function::Create(FTy, Function::ExternalLinkage, "", M.get());
     BB = BasicBlock::Create(Ctx, "", F);
 
     DIBuilder DIB(*M);
-    auto File = DIB.createFile("test.dbg", "/");
+    auto File = DIB.createFile("test.dbg", "/src", llvm::None,
+                               Optional<StringRef>("/src/test.dbg"));
     auto CU =
         DIB.createCompileUnit(dwarf::DW_LANG_C, File, "llvm-C", true, "", 0);
     auto Type = DIB.createSubroutineType(DIB.getOrCreateTypeArray(None));
     auto SP = DIB.createFunction(
         CU, "foo", "", File, 1, Type, 1, DINode::FlagZero,
         DISubprogram::SPFlagDefinition | DISubprogram::SPFlagOptimized);
     F->setSubprogram(SP);
     auto Scope = DIB.createLexicalBlockFile(SP, File, 0);
GlobalVariable *SrcStrGlob =
       cast<GlobalVariable>(Initializer->getOperand(4)->stripPointerCasts());
   if (!SrcStrGlob)
     return;
   EXPECT_TRUE(isa<ConstantDataArray>(SrcStrGlob->getInitializer()));
   ConstantDataArray *SrcSrc =
       dyn_cast<ConstantDataArray>(SrcStrGlob->getInitializer());
   if (!SrcSrc)
     return;
-  EXPECT_EQ(SrcSrc->getAsCString(), ";test.dbg;foo;3;7;;");
+  EXPECT_EQ(SrcSrc->getAsCString(), ";/src/test.dbg;foo;3;7;;");
 }
 
 TEST_F(OpenMPIRBuilderTest, ParallelSimple) {
   using InsertPointTy = OpenMPIRBuilder::InsertPointTy;
   OpenMPIRBuilder OMPBuilder(*M);
   OMPBuilder.initialize();
   F->setName("func");
   IRBuilder<> Builder(BB);