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[lld][WebAssembly] Fix relocation of Wasm table index with GOT access #104043

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[lld][WebAssembly] Fix relocation of Wasm table index with GOT access #104043

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d40eb7c
Fix relocation of Wasm table index with GOT access
luc-blaeser Aug 12, 2024
0a6c69b
Adjust FileCheck for `shared-call-indirect64.s`
luc-blaeser Aug 14, 2024
8bb7a87
Address review comments
luc-blaeser Aug 20, 2024
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126 changes: 126 additions & 0 deletions lld/test/wasm/shared-call-indirect.s
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Original file line number Diff line number Diff line change
@@ -0,0 +1,126 @@
# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t.o %s
# RUN: wasm-ld --experimental-pic -shared -o %t.wasm %t.o
# RUN: obj2yaml %t.wasm | FileCheck %s
# RUN: llvm-objdump --disassemble-symbols=test_indirect_local_func_call,test_indirect_shared_func_call --no-show-raw-insn --no-leading-addr %t.wasm | FileCheck %s --check-prefixes DIS

.globaltype __table_base, i32, immutable

test_indirect_local_func_call:
.functype test_indirect_local_func_call () -> ()
global.get __table_base
i32.const local_func@TBREL
i32.add
call_indirect () -> ()
end_function

# Test table index relocation in code section for shared functions

test_indirect_shared_func_call:
.functype test_indirect_shared_func_call () -> ()
i64.const 12345
global.get __table_base
i32.const shared_func@TBREL
i32.add
call_indirect (i64) -> (i32)
drop
end_function

local_func:
.functype local_func () -> ()
end_function

.globl shared_func
shared_func:
.functype shared_func (i64) -> (i32)
local.get 0
i32.wrap_i64
end_function

.globl _start
_start:
.functype _start () -> ()
call test_indirect_local_func_call
call test_indirect_shared_func_call
end_function

# CHECK: Sections:
# CHECK-NEXT: - Type: CUSTOM
# CHECK-NEXT: Name: dylink.0
# CHECK-NEXT: MemorySize: 0
# CHECK-NEXT: MemoryAlignment: 0
# CHECK-NEXT: TableSize: 2
# CHECK-NEXT: TableAlignment: 0
# CHECK-NEXT: Needed: []
# CHECK-NEXT: - Type: TYPE

# CHECK: - Type: IMPORT
# CHECK-NEXT: Imports:
# CHECK-NEXT: - Module: env
# CHECK-NEXT: Field: memory
# CHECK-NEXT: Kind: MEMORY
# CHECK-NEXT: Memory:
# CHECK-NEXT: Minimum: 0x0
# CHECK-NEXT: - Module: env
# CHECK-NEXT: Field: __indirect_function_table
# CHECK-NEXT: Kind: TABLE
# CHECK-NEXT: Table:
# CHECK-NEXT: Index: 0
# CHECK-NEXT: ElemType: FUNCREF
# CHECK-NEXT: Limits:
# CHECK-NEXT: Minimum: 0x2
# CHECK-NEXT: - Module: env
# CHECK-NEXT: Field: __memory_base
# CHECK-NEXT: Kind: GLOBAL
# CHECK-NEXT: GlobalType: I32
# CHECK-NEXT: GlobalMutable: false
# CHECK-NEXT: - Module: env
# CHECK-NEXT: Field: __table_base
# CHECK-NEXT: Kind: GLOBAL
# CHECK-NEXT: GlobalType: I32
# CHECK-NEXT: GlobalMutable: false
# CHECK-NEXT: - Module: GOT.func
# CHECK-NEXT: Field: shared_func
# CHECK-NEXT: Kind: GLOBAL
# CHECK-NEXT: GlobalType: I32
# CHECK-NEXT: GlobalMutable: true
# CHECK-NEXT: - Type: FUNCTION
# CHECK-NEXT: FunctionTypes: [ 0, 0, 0, 0, 0, 1, 0 ]
# CHECK-NEXT: - Type: EXPORT
# CHECK-NEXT: Exports:
# CHECK-NEXT: - Name: __wasm_call_ctors
# CHECK-NEXT: Kind: FUNCTION
# CHECK-NEXT: Index: 0
# CHECK-NEXT: - Name: __wasm_apply_data_relocs
# CHECK-NEXT: Kind: FUNCTION
# CHECK-NEXT: Index: 1
# CHECK-NEXT: - Name: shared_func
# CHECK-NEXT: Kind: FUNCTION
# CHECK-NEXT: Index: 5
# CHECK-NEXT: - Name: _start
# CHECK-NEXT: Kind: FUNCTION
# CHECK-NEXT: Index: 6
# CHECK-NEXT: - Type: ELEM
# CHECK-NEXT: Segments:
# CHECK-NEXT: - Offset:
# CHECK-NEXT: Opcode: GLOBAL_GET
# CHECK-NEXT: Index: 1
# CHECK-NEXT: Functions: [ 3, 5 ]


# DIS: <test_indirect_local_func_call>:
# DIS-EMPTY:
# DIS-NEXT: global.get 1
# DIS-NEXT: i32.const 0
# DIS-NEXT: i32.add
# DIS-NEXT: call_indirect 0
# DIS-NEXT: end

# DIS: <test_indirect_shared_func_call>:
# DIS-EMPTY:
# DIS-NEXT: i64.const 12345
# DIS-NEXT: global.get 1
# DIS-NEXT: i32.const 1
# DIS-NEXT: i32.add
# DIS-NEXT: call_indirect 1
# DIS-NEXT: drop
# DIS-NEXT: end
131 changes: 131 additions & 0 deletions lld/test/wasm/shared-call-indirect64.s
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Original file line number Diff line number Diff line change
@@ -0,0 +1,131 @@
# RUN: llvm-mc -filetype=obj -triple=wasm64-unknown-unknown -o %t.o %s
# RUN: wasm-ld -mwasm64 --experimental-pic -shared -o %t.wasm %t.o
# RUN: obj2yaml %t.wasm | FileCheck %s
# RUN: llvm-objdump --disassemble-symbols=test_indirect_local_func_call,test_indirect_shared_func_call --no-show-raw-insn --no-leading-addr %t.wasm | FileCheck %s --check-prefixes DIS

.globaltype __table_base, i64, immutable

test_indirect_local_func_call:
.functype test_indirect_local_func_call () -> ()
global.get __table_base
i64.const local_func@TBREL
i64.add
i32.wrap_i64 # Remove when table64 is supported
call_indirect () -> ()
end_function

# Test table index relocation in code section for shared functions

test_indirect_shared_func_call:
.functype test_indirect_shared_func_call () -> ()
i32.const 12345
global.get __table_base
i64.const shared_func@TBREL
i64.add
i32.wrap_i64 # Remove when table64 is supported
call_indirect (i32) -> (i32)
drop
end_function

local_func:
.functype local_func () -> ()
end_function

.globl shared_func
shared_func:
.functype shared_func (i32) -> (i32)
local.get 0
end_function

.globl _start
_start:
.functype _start () -> ()
call test_indirect_local_func_call
call test_indirect_shared_func_call
end_function

# CHECK: Sections:
# CHECK-NEXT: - Type: CUSTOM
# CHECK-NEXT: Name: dylink.0
# CHECK-NEXT: MemorySize: 0
# CHECK-NEXT: MemoryAlignment: 0
# CHECK-NEXT: TableSize: 2
# CHECK-NEXT: TableAlignment: 0
# CHECK-NEXT: Needed: []
# CHECK-NEXT: - Type: TYPE

# CHECK: - Type: IMPORT
# CHECK-NEXT: Imports:
# CHECK-NEXT: - Module: env
# CHECK-NEXT: Field: memory
# CHECK-NEXT: Kind: MEMORY
# CHECK-NEXT: Memory:
# CHECK-NEXT: Flags: [ IS_64 ]
# CHECK-NEXT: Minimum: 0x0
# CHECK-NEXT: - Module: env
# CHECK-NEXT: Field: __indirect_function_table
# CHECK-NEXT: Kind: TABLE
# CHECK-NEXT: Table:
# CHECK-NEXT: Index: 0
# CHECK-NEXT: ElemType: FUNCREF
# CHECK-NEXT: Limits:
# CHECK-NEXT: Flags: [ IS_64 ]
# CHECK-NEXT: Minimum: 0x2
# CHECK-NEXT: - Module: env
# CHECK-NEXT: Field: __memory_base
# CHECK-NEXT: Kind: GLOBAL
# CHECK-NEXT: GlobalType: I64
# CHECK-NEXT: GlobalMutable: false
# CHECK-NEXT: - Module: env
# CHECK-NEXT: Field: __table_base
# CHECK-NEXT: Kind: GLOBAL
# CHECK-NEXT: GlobalType: I64
# CHECK-NEXT: GlobalMutable: false
# CHECK-NEXT: - Module: GOT.func
# CHECK-NEXT: Field: shared_func
# CHECK-NEXT: Kind: GLOBAL
# CHECK-NEXT: GlobalType: I64
# CHECK-NEXT: GlobalMutable: true
# CHECK-NEXT: - Type: FUNCTION
# CHECK-NEXT: FunctionTypes: [ 0, 0, 0, 0, 0, 1, 0 ]
# CHECK-NEXT: - Type: EXPORT
# CHECK-NEXT: Exports:
# CHECK-NEXT: - Name: __wasm_call_ctors
# CHECK-NEXT: Kind: FUNCTION
# CHECK-NEXT: Index: 0
# CHECK-NEXT: - Name: __wasm_apply_data_relocs
# CHECK-NEXT: Kind: FUNCTION
# CHECK-NEXT: Index: 1
# CHECK-NEXT: - Name: shared_func
# CHECK-NEXT: Kind: FUNCTION
# CHECK-NEXT: Index: 5
# CHECK-NEXT: - Name: _start
# CHECK-NEXT: Kind: FUNCTION
# CHECK-NEXT: Index: 6
# CHECK-NEXT: - Type: ELEM
# CHECK-NEXT: Segments:
# CHECK-NEXT: - Offset:
# CHECK-NEXT: Opcode: GLOBAL_GET
# CHECK-NEXT: Index: 1
# CHECK-NEXT: Functions: [ 3, 5 ]


# DIS: <test_indirect_local_func_call>:
# DIS-EMPTY:
# DIS-NEXT: global.get 1
# DIS-NEXT: i64.const 0
# DIS-NEXT: i64.add
# DIS-NEXT: i32.wrap_i64
# DIS-NEXT: call_indirect 0
# DIS-NEXT: end

# DIS: <test_indirect_shared_func_call>:
# DIS-EMPTY:
# DIS-NEXT: i32.const 12345
# DIS-NEXT: global.get 1
# DIS-NEXT: i64.const 1
# DIS-NEXT: i64.add
# DIS-NEXT: i32.wrap_i64
# DIS-NEXT: call_indirect 1
# DIS-NEXT: drop
# DIS-NEXT: end
15 changes: 13 additions & 2 deletions lld/wasm/Relocations.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -102,13 +102,24 @@ void scanRelocations(InputChunk *chunk) {
switch (reloc.Type) {
case R_WASM_TABLE_INDEX_I32:
case R_WASM_TABLE_INDEX_I64:
// These relocations target the data section and are handled
// by `generateRelocationCode`. GOT accesses are handled below.
if (requiresGOTAccess(sym))
break;
out.elemSec->addEntry(cast<FunctionSymbol>(sym));
break;
case R_WASM_TABLE_INDEX_SLEB:
case R_WASM_TABLE_INDEX_SLEB64:
case R_WASM_TABLE_INDEX_REL_SLEB:
case R_WASM_TABLE_INDEX_REL_SLEB64:
// These relocations target the code section.
if (requiresGOTAccess(sym))
break;
out.elemSec->addEntry(cast<FunctionSymbol>(sym));
addGOTEntry(sym);
Comment on lines 116 to +117
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Maybe adding a GOT entry is not even needed for those PIC relocations (cf. discussion of #104920)?

// The indirect call needs a table element that can only be added
// for defined functions.
if (sym->isDefined())
out.elemSec->addEntry(cast<FunctionSymbol>(sym));
// Undefined symbols are handled below.
break;
case R_WASM_GLOBAL_INDEX_LEB:
case R_WASM_GLOBAL_INDEX_I32:
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