[ORC][COFF] Properly set weak flag to COMDAT symbols.

Properly set weak flag to COMDAT symbols so that no duplicate definition error will be generated. There is an inaccuracy in setting plain weak for largest selection type, which will be dealt with soon when largest type is properly implemented.

Reviewed By: lhames

Differential Revision: https://reviews.llvm.org/D129764

llvm/lib/ExecutionEngine/Orc/ObjectFileInterface.cpp

@@ -150,16 +150,39 @@ static Expected<MaterializationUnit::Interface>
 getCOFFObjectFileSymbolInfo(ExecutionSession &ES,
                             const object::COFFObjectFile &Obj) {
   MaterializationUnit::Interface I;
-
+  std::vector<Optional<object::coff_aux_section_definition>> ComdatDefs(
+      Obj.getNumberOfSections() + 1);
   for (auto &Sym : Obj.symbols()) {
     Expected<uint32_t> SymFlagsOrErr = Sym.getFlags();
     if (!SymFlagsOrErr)
       // TODO: Test this error.
       return SymFlagsOrErr.takeError();
 
-    // Skip symbols not defined in this object file.
+    // Handle comdat symbols
-    if (*SymFlagsOrErr & object::BasicSymbolRef::SF_Undefined)
+    auto COFFSym = Obj.getCOFFSymbol(Sym);
-      continue;
+    bool IsWeak = false;
+    if (auto *Def = COFFSym.getSectionDefinition()) {
+      auto Sec = Obj.getSection(COFFSym.getSectionNumber());
+      if (!Sec)
+        return Sec.takeError();
+      if (((*Sec)->Characteristics & COFF::IMAGE_SCN_LNK_COMDAT) &&
+          Def->Selection != COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE) {
+        ComdatDefs[COFFSym.getSectionNumber()] = *Def;
+        continue;
+      }
+    }
+    if (!COFF::isReservedSectionNumber(COFFSym.getSectionNumber()) &&
+        ComdatDefs[COFFSym.getSectionNumber()]) {
+      auto Def = ComdatDefs[COFFSym.getSectionNumber()];
+      if (Def->Selection != COFF::IMAGE_COMDAT_SELECT_NODUPLICATES) {
+        IsWeak = true;
+      }
+      ComdatDefs[COFFSym.getSectionNumber()] = None;
+    } else {
+      // Skip symbols not defined in this object file.
+      if (*SymFlagsOrErr & object::BasicSymbolRef::SF_Undefined)
+        continue;
+    }
 
     // Skip symbols that are not global.
     if (!(*SymFlagsOrErr & object::BasicSymbolRef::SF_Global))
@@ -180,12 +203,13 @@ getCOFFObjectFileSymbolInfo(ExecutionSession &ES,
     if (!SymFlags)
       return SymFlags.takeError();
     *SymFlags |= JITSymbolFlags::Exported;
-    auto COFFSym = Obj.getCOFFSymbol(Sym);
 
     // Weak external is always a function
-    if (COFFSym.isWeakExternal()) {
+    if (COFFSym.isWeakExternal())
       *SymFlags |= JITSymbolFlags::Callable;
-    }
+
+    if (IsWeak)
+      *SymFlags |= JITSymbolFlags::Weak;
 
     I.SymbolFlags[ES.intern(*Name)] = std::move(*SymFlags);
   }

llvm/test/ExecutionEngine/JITLink/X86/COFF_comdat_weak_duplicate.s

@@ -0,0 +1,29 @@
+# RUN: rm -rf %t && mkdir -p %t
+# RUN: yaml2obj %S/Inputs/COFF_comdat_weak_def.yaml -o %t/COFF_weak_1.o
+# RUN: yaml2obj %S/Inputs/COFF_comdat_weak_def.yaml -o %t/COFF_weak_2.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-windows-msvc %s -o %t/COFF_main.o
+# RUN: 
+# RUN: llvm-jitlink -noexec %t/COFF_main.o %t/COFF_weak_1.o %t/COFF_weak_2.o \
+# RUN: -slab-allocate 100Kb -slab-address 0xfff00000 -slab-page-size 4096 \
+# RUN: -show-graph -noexec 2>&1 | FileCheck %s
+#
+# Check that duplicate comdat any definitions don't generate duplicate definition error.
+#
+# CHECK: section weakfunc:
+# CHECK-EMPTY:
+# CHECK-NEXT:  block 0xfff02000 size = 0x00000001, align = 16, alignment-offset = 0
+# CHECK-NEXT:    symbols:
+# CHECK-NEXT:      0xfff02000 (block + 0x00000000): size: 0x00000001, linkage: weak, scope: default, live  -   func
+# CHECK-NEXT:    no edges
+
+	.text
+
+	.def	main;
+	.scl	2;
+	.type	32;
+	.endef
+	.globl	main
+	.p2align	4, 0x90
+main:
+    callq func
+	retq

llvm/test/ExecutionEngine/JITLink/X86/COFF_comdat_weak_plus_strong.s

@@ -0,0 +1,32 @@
+# FIXME: Comdat any + ordinary strong symbol should generate duplicate section error
+# XFAIL: *
+# RUN: rm -rf %t && mkdir -p %t
+# RUN: yaml2obj %S/Inputs/COFF_comdat_weak_def.yaml -o %t/COFF_weak_1.o
+# RUN: yaml2obj %S/Inputs/COFF_strong_def.yaml -o %t/COFF_strong.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-windows-msvc %s -o %t/COFF_main.o
+# RUN: 
+# RUN: not llvm-jitlink -noexec %t/COFF_main.o %t/COFF_weak_1.o %t/COFF_strong.o \
+# RUN: -slab-allocate 100Kb -slab-address 0xfff00000 -slab-page-size 4096 \
+# RUN: -show-graph -noexec 2>&1 | FileCheck %s
+#
+# Check that a combination of comdat any definition and strong definition generate 
+# duplicate definition error.
+#
+# CHECK: section strongfunc:
+# CHECK-EMPTY:
+# CHECK-NEXT:  block 0xfff02000 size = 0x00000001, align = 16, alignment-offset = 0
+# CHECK-NEXT:    symbols:
+# CHECK-NEXT:      0xfff02000 (block + 0x00000000): size: 0x00000001, linkage: strong, scope: default, live  -   func
+# CHECK-NEXT:    no edges
+
+	.text
+
+	.def	main;
+	.scl	2;
+	.type	32;
+	.endef
+	.globl	main
+	.p2align	4, 0x90
+main:
+    callq func
+	retq

llvm/test/ExecutionEngine/JITLink/X86/COFF_strong_duplicate.s

@@ -0,0 +1,23 @@
+# RUN: rm -rf %t && mkdir -p %t
+# RUN: yaml2obj %S/Inputs/COFF_strong_def.yaml -o %t/COFF_strong_1.o
+# RUN: yaml2obj %S/Inputs/COFF_strong_def.yaml -o %t/COFF_strong_2.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-windows-msvc %s -o %t/COFF_main.o
+# RUN: 
+# RUN: not llvm-jitlink -noexec %t/COFF_main.o %t/COFF_strong_1.o %t/COFF_strong_2.o \
+# RUN: -slab-allocate 100Kb -slab-address 0xfff00000 -slab-page-size 4096 \
+# RUN: -show-graph
+#
+# Check that duplicate strong definitions cause llvm-jitlink to terminate with error.
+#
+
+	.text
+
+	.def	main;
+	.scl	2;
+	.type	32;
+	.endef
+	.globl	main
+	.p2align	4, 0x90
+main:
+    callq func
+	retq

llvm/test/ExecutionEngine/JITLink/X86/Inputs/COFF_comdat_weak_def.yaml

@@ -0,0 +1,30 @@
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_AMD64
+  Characteristics: [  ]
+sections:
+  - Name:            weakfunc
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_LNK_COMDAT, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    SectionData:     C3
+symbols:
+  - Name:            weakfunc
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          1
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        40735498
+      Number:          1
+      Selection:       IMAGE_COMDAT_SELECT_ANY
+  - Name:            func
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...

llvm/test/ExecutionEngine/JITLink/X86/Inputs/COFF_strong_def.yaml

@@ -0,0 +1,29 @@
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_AMD64
+  Characteristics: [  ]
+sections:
+  - Name:            strongfunc
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    SectionData:     C3
+symbols:
+  - Name:            strongfunc
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          1
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        40735498
+      Number:          1
+  - Name:            func
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...