[JITLink][COFF] Don't dead strip COMDAT associative symbol.

This prevents the dead strip of associative comdat section when parent section is alive.

Reviewed By: sgraenitz

Differential Revision: https://reviews.llvm.org/D129720

diff --git a/llvm/lib/ExecutionEngine/JITLink/COFFLinkGraphBuilder.cpp b/llvm/lib/ExecutionEngine/JITLink/COFFLinkGraphBuilder.cpp
index dc07eae..9638f49 100644 (file)
--- a/llvm/lib/ExecutionEngine/JITLink/COFFLinkGraphBuilder.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/COFFLinkGraphBuilder.cpp
@@ -422,10 +422,12 @@ Expected<Symbol *> COFFLinkGraphBuilder::createDefinedSymbol(
           Symbol.getComplexType() == COFF::IMAGE_SYM_DTYPE_FUNCTION, false);
     }
     if (Definition->Selection == COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE) {
-      // FIXME: don't dead strip this when parent section is alive
-      return &G->addDefinedSymbol(
+      auto Target = Definition->getNumber(Symbol.isBigObj());
+      auto GSym = &G->addDefinedSymbol(
           *B, Symbol.getValue(), SymbolName, 0, Linkage::Strong, Scope::Local,
           Symbol.getComplexType() == COFF::IMAGE_SYM_DTYPE_FUNCTION, false);
+      getGraphBlock(Target)->addEdge(Edge::KeepAlive, 0, *GSym, 0);
+      return GSym;
     }
     if (PendingComdatExport)
       return make_error<JITLinkError>(

diff --git a/llvm/test/ExecutionEngine/JITLink/X86/COFF_comdat_associative_dead_strip.test b/llvm/test/ExecutionEngine/JITLink/X86/COFF_comdat_associative_dead_strip.test
new file mode 100644 (file)
index 0000000..dd2e4bc
--- /dev/null
+++ b/llvm/test/ExecutionEngine/JITLink/X86/COFF_comdat_associative_dead_strip.test
@@ -0,0 +1,63 @@
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-jitlink -noexec \
+# RUN: -slab-allocate 100Kb -slab-address 0xfff00000 -slab-page-size 4096 \
+# RUN: -show-graph -noexec %t 2>&1 | FileCheck %s
+# 
+# Check a comdat child block connected by associative selection type is dead strip when
+# parent block is dead.
+#
+# CHECK: section parent:
+# CHECK-EMPTY:
+# CHECK-NEXT: section child:
+# CHECK-EMPTY:
+
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_AMD64
+  Characteristics: [  ]
+sections:
+  - Name:            .text
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    SectionData:     '0000000000000000'
+  - Name:            parent
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    SectionData:     '0000000000000000'
+  - Name:            child
+    Characteristics: [ IMAGE_SCN_CNT_INITIALIZED_DATA, IMAGE_SCN_LNK_COMDAT, IMAGE_SCN_MEM_READ ]
+    Alignment:       4
+    SectionData:     '0000000000000000'
+symbols:
+  - Name:            .text
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          8
+      NumberOfRelocations: 0
+      CheckSum:            0
+      NumberOfLinenumbers: 0
+      Number:          1
+  - Name:            child
+    Value:           0
+    SectionNumber:   3
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          4
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      Number:          2
+      CheckSum:  0
+      Selection:       IMAGE_COMDAT_SELECT_ASSOCIATIVE
+  - Name:            main
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...

diff --git a/llvm/test/ExecutionEngine/JITLink/X86/COFF_comdat_associative_no_dead_strip.test b/llvm/test/ExecutionEngine/JITLink/X86/COFF_comdat_associative_no_dead_strip.test
new file mode 100644 (file)
index 0000000..2979d5b
--- /dev/null
+++ b/llvm/test/ExecutionEngine/JITLink/X86/COFF_comdat_associative_no_dead_strip.test
@@ -0,0 +1,88 @@
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-jitlink -noexec \
+# RUN: -slab-allocate 100Kb -slab-address 0xfff00000 -slab-page-size 4096 \
+# RUN: -show-graph -noexec %t 2>&1 | FileCheck %s
+# 
+# Check a comdat child block connected by associative selection type is not dead strip when
+# parent block is alive.
+#
+# CHECK: section child:
+# CHECK-EMPTY:
+# CHECK-NEXT: block 0xfff00000 size = 0x00000008, align = 4, alignment-offset = 0
+# CHECK-NEXT:   symbols:
+# CHECK-NEXT:     0xfff00000 (block + 0x00000000): size: 0x00000008, linkage: strong, scope: local, live  -   child
+# CHECK-NEXT:   no edges
+
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_AMD64
+  Characteristics: [  ]
+sections:
+  - Name:            .text
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    SectionData:     '0000000000000000'
+    Relocations:
+      - VirtualAddress:  0
+        SymbolTableIndex: 2
+        Type:            IMAGE_REL_AMD64_REL32
+  - Name:            parent
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_LNK_COMDAT, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    SectionData:     '0000000000000000'
+  - Name:            child
+    Characteristics: [ IMAGE_SCN_CNT_INITIALIZED_DATA, IMAGE_SCN_LNK_COMDAT, IMAGE_SCN_MEM_READ ]
+    Alignment:       4
+    SectionData:     '0000000000000000'
+symbols:
+  - Name:            .text
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          8
+      NumberOfRelocations: 0
+      CheckSum:            0
+      NumberOfLinenumbers: 0
+      Number:          1
+  - Name:            .text
+    Value:           0
+    SectionNumber:   2
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          8
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:  0
+      Number:          3
+      Selection:       IMAGE_COMDAT_SELECT_ANY
+  - Name:            func
+    Value:           0
+    SectionNumber:   2
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+  - Name:            child
+    Value:           0
+    SectionNumber:   3
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          4
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      Number:          2
+      CheckSum:  0
+      Selection:       IMAGE_COMDAT_SELECT_ASSOCIATIVE
+  - Name:            main
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...