[WebAssembly] Implement @llvm.global_ctors and @llvm.global_dtors

Summary:
- lowers @llvm.global_dtors by adding @llvm.global_ctors
  functions which register the destructors with `__cxa_atexit`.
- impements @llvm.global_ctors with wasm start functions and linker metadata

See [here](https://github.com/WebAssembly/tool-conventions/issues/25) for more background.

Subscribers: jfb, dschuff, mgorny, jgravelle-google, aheejin, sunfish

Differential Revision: https://reviews.llvm.org/D41211

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@320774 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 112 insertions, 39 deletions

diff --git a/test/MC/WebAssembly/init-fini-array.ll b/test/MC/WebAssembly/init-fini-array.ll
index 0a809a226c4..ddcdd1a0c41 100644
--- a/test/MC/WebAssembly/init-fini-array.ll
+++ b/test/MC/WebAssembly/init-fini-array.ll
@@ -2,13 +2,14 @@
 
 @global1 = global i32 1025, align 8
 
+declare void @func0()
 declare void @func1()
-
 declare void @func2()
+declare void @func3()
 
-@llvm.global_ctors = appending global [1 x { i32, void ()*, i8* }] [{ i32, void ()*, i8* } { i32 65535, void ()* @func1, i8* null }] 
+@llvm.global_ctors = appending global [2 x { i32, void ()*, i8* }] [{ i32, void ()*, i8* } { i32 65535, void ()* @func0, i8* null }, { i32, void ()*, i8* } { i32 42, void ()* @func1, i8* null }] 
 
-@llvm.global_dtors = appending global [1 x { i32, void ()*, i8* }] [{ i32, void ()*, i8* } { i32 65535, void ()* @func2, i8* null }]
+@llvm.global_dtors = appending global [2 x { i32, void ()*, i8* }] [{ i32, void ()*, i8* } { i32 65535, void ()* @func2, i8* null }, { i32, void ()*, i8* } { i32 42, void ()* @func3, i8* null }] 
   
 
 ; CHECK:        - Type:            IMPORT
@@ -16,23 +17,42 @@ declare void @func2()
 ; CHECK-NEXT:       - Module:          env
 ; CHECK-NEXT:         Field:           __linear_memory
 ; CHECK-NEXT:         Kind:            MEMORY
-; CHECK-NEXT:         Memory:
+; CHECK-NEXT:         Memory:          
 ; CHECK-NEXT:           Initial:         0x00000001
 ; CHECK-NEXT:       - Module:          env
 ; CHECK-NEXT:         Field:           __indirect_function_table
 ; CHECK-NEXT:         Kind:            TABLE
-; CHECK-NEXT:         Table:
+; CHECK-NEXT:         Table:           
 ; CHECK-NEXT:           ElemType:        ANYFUNC
-; CHECK-NEXT:           Limits:
+; CHECK-NEXT:           Limits:          
 ; CHECK-NEXT:             Initial:         0x00000002
 ; CHECK-NEXT:       - Module:          env
-; CHECK-NEXT:         Field:           func1
+; CHECK-NEXT:         Field:           func3
+; CHECK-NEXT:         Kind:            FUNCTION
+; CHECK-NEXT:         SigIndex:        1
+; CHECK-NEXT:       - Module:          env
+; CHECK-NEXT:         Field:           __dso_handle
+; CHECK-NEXT:         Kind:            GLOBAL
+; CHECK-NEXT:         GlobalType:      I32
+; CHECK-NEXT:         GlobalMutable:   false
+; CHECK-NEXT:       - Module:          env
+; CHECK-NEXT:         Field:           __cxa_atexit
 ; CHECK-NEXT:         Kind:            FUNCTION
-; CHECK-NEXT:         SigIndex:        0
+; CHECK-NEXT:         SigIndex:        2
 ; CHECK-NEXT:       - Module:          env
 ; CHECK-NEXT:         Field:           func2
 ; CHECK-NEXT:         Kind:            FUNCTION
-; CHECK-NEXT:         SigIndex:        0
+; CHECK-NEXT:         SigIndex:        1
+; CHECK-NEXT:       - Module:          env
+; CHECK-NEXT:         Field:           func1
+; CHECK-NEXT:         Kind:            FUNCTION
+; CHECK-NEXT:         SigIndex:        1
+; CHECK-NEXT:       - Module:          env
+; CHECK-NEXT:         Field:           func0
+; CHECK-NEXT:         Kind:            FUNCTION
+; CHECK-NEXT:         SigIndex:        1
+; CHECK-NEXT:   - Type:            FUNCTION
+; CHECK-NEXT:     FunctionTypes:   [ 0, 1, 0, 1 ]
 ; CHECK-NEXT:   - Type:            GLOBAL
 ; CHECK-NEXT:     Globals:         
 ; CHECK-NEXT:       - Type:            I32
@@ -42,23 +62,63 @@ declare void @func2()
 ; CHECK-NEXT:           Value:           0
 ; CHECK-NEXT:   - Type:            EXPORT
 ; CHECK-NEXT:     Exports:         
+; CHECK-NEXT:       - Name:            .Lcall_dtors.42
+; CHECK-NEXT:         Kind:            FUNCTION
+; CHECK-NEXT:         Index:           5
+; CHECK-NEXT:       - Name:            .Lregister_call_dtors.42
+; CHECK-NEXT:         Kind:            FUNCTION
+; CHECK-NEXT:         Index:           6
+; CHECK-NEXT:       - Name:            .Lcall_dtors
+; CHECK-NEXT:         Kind:            FUNCTION
+; CHECK-NEXT:         Index:           7
+; CHECK-NEXT:       - Name:            .Lregister_call_dtors
+; CHECK-NEXT:         Kind:            FUNCTION
+; CHECK-NEXT:         Index:           8
 ; CHECK-NEXT:       - Name:            global1
 ; CHECK-NEXT:         Kind:            GLOBAL
-; CHECK-NEXT:         Index:           0
+; CHECK-NEXT:         Index:           1
 ; CHECK-NEXT:   - Type:            ELEM
 ; CHECK-NEXT:     Segments:        
 ; CHECK-NEXT:       - Offset:          
 ; CHECK-NEXT:           Opcode:          I32_CONST
 ; CHECK-NEXT:           Value:           0
-; CHECK-NEXT:         Functions:       [ 0, 1 ]
-; CHECK-NEXT:   - Type:            DATA
+; CHECK-NEXT:         Functions:       [ 5, 7 ]
+; CHECK-NEXT:   - Type:            CODE
 ; CHECK-NEXT:     Relocations:     
-; CHECK-NEXT:       - Type:            R_WEBASSEMBLY_TABLE_INDEX_I32
+; CHECK-NEXT:       - Type:            R_WEBASSEMBLY_FUNCTION_INDEX_LEB
+; CHECK-NEXT:         Index:           0
+; CHECK-NEXT:         Offset:          0x00000004
+; CHECK-NEXT:       - Type:            R_WEBASSEMBLY_TABLE_INDEX_SLEB
 ; CHECK-NEXT:         Index:           0
 ; CHECK-NEXT:         Offset:          0x0000000F
-; CHECK-NEXT:       - Type:            R_WEBASSEMBLY_TABLE_INDEX_I32
+; CHECK-NEXT:       - Type:            R_WEBASSEMBLY_MEMORY_ADDR_SLEB
+; CHECK-NEXT:         Index:           0
+; CHECK-NEXT:         Offset:          0x00000017
+; CHECK-NEXT:       - Type:            R_WEBASSEMBLY_FUNCTION_INDEX_LEB
+; CHECK-NEXT:         Index:           1
+; CHECK-NEXT:         Offset:          0x0000001D
+; CHECK-NEXT:       - Type:            R_WEBASSEMBLY_FUNCTION_INDEX_LEB
+; CHECK-NEXT:         Index:           2
+; CHECK-NEXT:         Offset:          0x0000002C
+; CHECK-NEXT:       - Type:            R_WEBASSEMBLY_TABLE_INDEX_SLEB
 ; CHECK-NEXT:         Index:           1
-; CHECK-NEXT:         Offset:          0x00000018
+; CHECK-NEXT:         Offset:          0x00000037
+; CHECK-NEXT:       - Type:            R_WEBASSEMBLY_MEMORY_ADDR_SLEB
+; CHECK-NEXT:         Index:           0
+; CHECK-NEXT:         Offset:          0x0000003F
+; CHECK-NEXT:       - Type:            R_WEBASSEMBLY_FUNCTION_INDEX_LEB
+; CHECK-NEXT:         Index:           1
+; CHECK-NEXT:         Offset:          0x00000045
+; CHECK-NEXT:     Functions:       
+; CHECK-NEXT:       - Locals:          
+; CHECK-NEXT:         Body:            1080808080000B
+; CHECK-NEXT:       - Locals:          
+; CHECK-NEXT:         Body:            0240418080808000410041FFFFFFFF7F1081808080000D000F0B00000B
+; CHECK-NEXT:       - Locals:          
+; CHECK-NEXT:         Body:            1082808080000B
+; CHECK-NEXT:       - Locals:          
+; CHECK-NEXT:         Body:            0240418180808000410041FFFFFFFF7F1081808080000D000F0B00000B
+; CHECK-NEXT:   - Type:            DATA
 ; CHECK-NEXT:     Segments:        
 ; CHECK-NEXT:       - SectionOffset:   6
 ; CHECK-NEXT:         MemoryIndex:     0
@@ -66,40 +126,53 @@ declare void @func2()
 ; CHECK-NEXT:           Opcode:          I32_CONST
 ; CHECK-NEXT:           Value:           0
 ; CHECK-NEXT:         Content:         '01040000'
-; CHECK-NEXT:       - SectionOffset:   15
-; CHECK-NEXT:         MemoryIndex:     0
-; CHECK-NEXT:         Offset:          
-; CHECK-NEXT:           Opcode:          I32_CONST
-; CHECK-NEXT:           Value:           4
-; CHECK-NEXT:         Content:         '00000000'
-; CHECK-NEXT:       - SectionOffset:   24
-; CHECK-NEXT:         MemoryIndex:     0
-; CHECK-NEXT:         Offset:          
-; CHECK-NEXT:           Opcode:          I32_CONST
-; CHECK-NEXT:           Value:           8
-; CHECK-NEXT:         Content:         '01000000'
 ; CHECK-NEXT:   - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            name
 ; CHECK-NEXT:     FunctionNames:   
 ; CHECK-NEXT:       - Index:           0
-; CHECK-NEXT:         Name:            func1
+; CHECK-NEXT:         Name:            func3
 ; CHECK-NEXT:       - Index:           1
+; CHECK-NEXT:         Name:            __cxa_atexit
+; CHECK-NEXT:       - Index:           2
 ; CHECK-NEXT:         Name:            func2
+; CHECK-NEXT:       - Index:           3
+; CHECK-NEXT:         Name:            func1
+; CHECK-NEXT:       - Index:           4
+; CHECK-NEXT:         Name:            func0
+; CHECK-NEXT:       - Index:           5
+; CHECK-NEXT:         Name:            .Lcall_dtors.42
+; CHECK-NEXT:       - Index:           6
+; CHECK-NEXT:         Name:            .Lregister_call_dtors.42
+; CHECK-NEXT:       - Index:           7
+; CHECK-NEXT:         Name:            .Lcall_dtors
+; CHECK-NEXT:       - Index:           8
+; CHECK-NEXT:         Name:            .Lregister_call_dtors
 ; CHECK-NEXT:   - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            linking
-; CHECK-NEXT:     DataSize:        12
-; CHECK-NEXT:     SegmentInfo:
+; CHECK-NEXT:     DataSize:        4
+; CHECK-NEXT:     SymbolInfo:      
+; CHECK-NEXT:       - Name:            __dso_handle
+; CHECK-NEXT:         Flags:           [ BINDING_WEAK, VISIBILITY_HIDDEN ]
+; CHECK-NEXT:       - Name:            .Lcall_dtors.42
+; CHECK-NEXT:         Flags:           [ BINDING_LOCAL ]
+; CHECK-NEXT:       - Name:            .Lregister_call_dtors.42
+; CHECK-NEXT:         Flags:           [ BINDING_LOCAL ]
+; CHECK-NEXT:       - Name:            .Lcall_dtors
+; CHECK-NEXT:         Flags:           [ BINDING_LOCAL ]
+; CHECK-NEXT:       - Name:            .Lregister_call_dtors
+; CHECK-NEXT:         Flags:           [ BINDING_LOCAL ]
+; CHECK-NEXT:     SegmentInfo:     
 ; CHECK-NEXT:       - Index:           0
 ; CHECK-NEXT:         Name:            .data.global1
 ; CHECK-NEXT:         Alignment:       8
 ; CHECK-NEXT:         Flags:           [ ]
-; CHECK-NEXT:       - Index:           1
-; CHECK-NEXT:         Name:            .init_array
-; CHECK-NEXT:         Alignment:       4
-; CHECK-NEXT:         Flags:           [ ]
-; CHECK-NEXT:       - Index:           2
-; CHECK-NEXT:         Name:            .fini_array
-; CHECK-NEXT:         Alignment:       4
-; CHECK-NEXT:         Flags:           [ ]
+; CHECK-NEXT:     InitFunctions:     
+; CHECK-NEXT:       - Priority: 42
+; CHECK-NEXT:         FunctionIndex: 3
+; CHECK-NEXT:       - Priority: 42
+; CHECK-NEXT:         FunctionIndex: 6
+; CHECK-NEXT:       - Priority: 65535
+; CHECK-NEXT:         FunctionIndex: 4
+; CHECK-NEXT:       - Priority: 65535
+; CHECK-NEXT:         FunctionIndex: 8
 ; CHECK-NEXT: ...
-