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[lld][WebAssembly] Report undefined symbols in -shared/-pie builds (#75242)
Previously we would ignore all undefined symbols when using `-shared` or `-pie`. All undefined symbols would be treated as imports regardless of whether those symbols we defined in any shared library. With this change we now track symbol in shared libraries and report undefined symbols in the main program by default. The old behavior is still available via the `--unresolved-symbols=import-dynamic` command line flag. This rationale for allowing this type of breaking change is that `-pie` and `-shared` are both still experimental will warn as such, unless `--experimental-pic` is passed. As part of this change the linker now models shared library symbols via new SharedFunctionSymbol and SharedDataSymbol types. I've also added a new `--no-shlib-sigcheck` option that bypassed the checking of functions signature in shared libraries. This is specifically required by emscripten the case where the imports/exports of shared libraries have been modified by via JS type legalization (this is only needed when targeting old JS engines where bigint is not yet available See emscripten-core/emscripten#18198
1 parent ef8207b commit 22b7b84

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‎lld/test/wasm/Inputs/ret32.s

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.hidden ret32
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.globl ret32
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ret32:
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.functype ret32 (f32) -> (i32)

‎lld/test/wasm/dylink.s

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# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-emscripten -o %t.o %s
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# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-emscripten %p/Inputs/ret32.s -o %t.ret32.o
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# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-emscripten %p/Inputs/libsearch-dyn.s -o %t.dyn.o
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# RUN: wasm-ld --experimental-pic -shared %t.ret32.o %t.dyn.o -o %t.lib.so
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# RUN: not wasm-ld --experimental-pic -pie -o %t.wasm %t.o 2>&1 | FileCheck --check-prefix=ERROR %s
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# RUN: wasm-ld --experimental-pic -pie -o %t.wasm %t.o %t.lib.so
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# RUN: obj2yaml %t.wasm | FileCheck %s
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# ERROR: error: {{.*}}: undefined symbol: ret32
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# ERROR: error: {{.*}}: undefined symbol: _bar
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.functype ret32 (f32) -> (i32)
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.globl _start
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_start:
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.functype _start () -> ()
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f32.const 0.0
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call ret32
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drop
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i32.const _bar@GOT
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drop
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end_function
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# CHECK: Sections:
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# CHECK-NEXT: - Type: CUSTOM
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# CHECK-NEXT: Name: dylink.0
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# CHECK-NEXT: MemorySize: 0
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# CHECK-NEXT: MemoryAlignment: 0
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# CHECK-NEXT: TableSize: 0
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# CHECK-NEXT: TableAlignment: 0
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# CHECK-NEXT: Needed:
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# CHECK-NEXT: - {{.*}}.lib.so

‎lld/test/wasm/emit-relocs.s

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@@ -54,7 +54,7 @@ foo:
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# CHECK-NEXT: - Index: 1
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# CHECK-NEXT: Kind: FUNCTION
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# CHECK-NEXT: Name: ret32
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# CHECK-NEXT: Flags: [ VISIBILITY_HIDDEN ]
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# CHECK-NEXT: Flags: [ ]
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# CHECK-NEXT: Function: 1
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# CHECK-NEXT: - Index: 2
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# CHECK-NEXT: Kind: DATA

‎lld/test/wasm/no-shlib-sigcheck.s

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# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-emscripten -o %t.o %s
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# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-emscripten %p/Inputs/ret32.s -o %t.ret32.o
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# RUN: wasm-ld --experimental-pic -shared %t.ret32.o -o %t.lib.so
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## Fails with signature mismatch by default
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# RUN: not wasm-ld --experimental-pic -pie -o %t.wasm %t.o %t.lib.so 2>&1 | FileCheck --check-prefix=ERROR %s
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## Same again with shared library first.
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# RUN: not wasm-ld --experimental-pic -pie -o %t.wasm %t.lib.so %t.o 2>&1 | FileCheck --check-prefix=ERROR %s
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## Succeeds with --no-shlib-sigcheck added
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# RUN: wasm-ld --experimental-pic -pie -o %t.wasm %t.o %t.lib.so --no-shlib-sigcheck
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# RUN: obj2yaml %t.wasm | FileCheck %s
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## Same again with shared library first.
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# RUN: wasm-ld --experimental-pic -pie -o %t.wasm %t.lib.so %t.o --no-shlib-sigcheck
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# RUN: obj2yaml %t.wasm | FileCheck %s
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.functype ret32 (f32) -> (i64)
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.globl _start
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_start:
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.functype _start () -> ()
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f32.const 0.0
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call ret32
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drop
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end_function
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# ERROR: wasm-ld: error: function signature mismatch: ret32
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# ERROR: >>> defined as (f32) -> i64 in {{.*}}.o
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# CHECK: - Type: TYPE
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# CHECK-NEXT: Signatures:
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# CHECK-NEXT: - Index: 0
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# CHECK-NEXT: ParamTypes:
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# CHECK-NEXT: - F32
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# CHECK-NEXT: ReturnTypes:
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# CHECK-NEXT: - I64
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# CHECK-NEXT: - Index: 1
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# CHECK-NEXT: ParamTypes: []
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# CHECK-NEXT: ReturnTypes: []

‎lld/test/wasm/pie.s

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@@ -1,6 +1,6 @@
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# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-emscripten -o %t.o %s
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# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-emscripten %S/Inputs/internal_func.s -o %t.internal_func.o
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# RUN: wasm-ld --no-gc-sections --experimental-pic -pie -o %t.wasm %t.o %t.internal_func.o
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# RUN: wasm-ld --no-gc-sections --experimental-pic -pie --unresolved-symbols=import-dynamic -o %t.wasm %t.o %t.internal_func.o
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# RUN: obj2yaml %t.wasm | FileCheck %s
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# RUN: llvm-objdump --disassemble-symbols=__wasm_call_ctors,__wasm_apply_data_relocs --no-show-raw-insn --no-leading-addr %t.wasm | FileCheck %s --check-prefixes DISASSEM
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# instruction in the InitExpr. We also, therefore, do not need these globals
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# to be mutable.
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# RUN: wasm-ld --no-gc-sections --experimental-pic -pie --extra-features=extended-const -o %t.extended.wasm %t.o %t.internal_func.o
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# RUN: wasm-ld --no-gc-sections --experimental-pic -pie --unresolved-symbols=import-dynamic --extra-features=extended-const -o %t.extended.wasm %t.o %t.internal_func.o
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# RUN: obj2yaml %t.extended.wasm | FileCheck %s --check-prefix=EXTENDED-CONST
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# EXTENDED-CONST-NOT: __wasm_apply_global_relocs
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# to be generated along with __wasm_start as the start
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# function.
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# RUN: wasm-ld --no-gc-sections --shared-memory --experimental-pic -pie -o %t.shmem.wasm %t.o %t.internal_func.o
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# RUN: wasm-ld --no-gc-sections --shared-memory --experimental-pic -pie --unresolved-symbols=import-dynamic -o %t.shmem.wasm %t.o %t.internal_func.o
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# RUN: obj2yaml %t.shmem.wasm | FileCheck %s --check-prefix=SHMEM
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# RUN: llvm-objdump --disassemble-symbols=__wasm_start --no-show-raw-insn --no-leading-addr %t.shmem.wasm | FileCheck %s --check-prefix DISASSEM-SHMEM
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‎lld/test/wasm/shared-needed.s

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# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t.o %s
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# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown %p/Inputs/ret32.s -o %t.ret32.o
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# RUN: wasm-ld -shared --experimental-pic -o %t1.so %t.o
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# RUN: obj2yaml %t1.so | FileCheck %s -check-prefix=SO1
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# RUN: wasm-ld -shared --experimental-pic -o %t.ret32.so %t.ret32.o
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# RUN: obj2yaml %t.ret32.so | FileCheck %s -check-prefix=SO1
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# Without linking against the ret32.so shared object we expect an undefined
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# symbol error
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# RUN: not wasm-ld -shared --experimental-pic -o %t.so %t.o 2>&1 | FileCheck %s --check-prefix=ERROR
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# ERROR: undefined symbol: ret32
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# RUN: wasm-ld -shared --experimental-pic -o %t.so %t.o %t.ret32.so
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# RUN: obj2yaml %t.so | FileCheck %s -check-prefix=SO2
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# RUN: wasm-ld -shared --experimental-pic -o %t2.so %t1.so %t.ret32.o
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# RUN: obj2yaml %t2.so | FileCheck %s -check-prefix=SO2
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.globl foo
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.globl data
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.functype ret32 (f32) -> (i32)
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foo:
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.functype foo () -> ()
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.functype foo (f32) -> (i32)
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local.get 0
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call ret32
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end_function
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.section .data,"",@
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# SO1: Sections:
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# SO1-NEXT: - Type: CUSTOM
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# SO1-NEXT: Name: dylink.0
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# SO1-NEXT: MemorySize: 4
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# SO1-NEXT: MemoryAlignment: 2
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# SO1-NEXT: MemorySize: 0
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# SO1-NEXT: MemoryAlignment: 0
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# SO1-NEXT: TableSize: 0
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# SO1-NEXT: TableAlignment: 0
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# SO1-NEXT: Needed: []
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# SO2: Sections:
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# SO2-NEXT: - Type: CUSTOM
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# SO2-NEXT: Name: dylink.0
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# SO2-NEXT: MemorySize: 0
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# SO2-NEXT: MemoryAlignment: 0
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# SO2-NEXT: MemorySize: 4
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# SO2-NEXT: MemoryAlignment: 2
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# SO2-NEXT: TableSize: 0
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# SO2-NEXT: TableAlignment: 0
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# SO2-NEXT: Needed:
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# SO2-NEXT: - shared-needed.s.tmp1.so
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# SO2-NEXT: - shared-needed.s.tmp.ret32.so
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# SO2-NEXT: - Type: TYPE

‎lld/test/wasm/shared.s

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# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t.o %s
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# RUN: wasm-ld --experimental-pic -shared -o %t.wasm %t.o
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# RUN: wasm-ld --experimental-pic --unresolved-symbols=import-dynamic -shared -o %t.wasm %t.o
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# RUN: obj2yaml %t.wasm | FileCheck %s
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# RUN: llvm-objdump --disassemble-symbols=__wasm_call_ctors,__wasm_apply_data_relocs --no-show-raw-insn --no-leading-addr %t.wasm | FileCheck %s --check-prefixes DIS
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.functype func_external () -> ()
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# Linker-synthesized globals
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.globaltype __stack_pointer, i32
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.globaltype __table_base, i32, immutable
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.globaltype __memory_base, i32, immutable
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.globaltype __table_base, i32, immutable
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.globaltype __memory_base, i32, immutable
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.section .data.data,"",@
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data:

‎lld/test/wasm/shared64.s

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# RUN: llvm-mc -filetype=obj -triple=wasm64-unknown-unknown -o %t.o %s
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# RUN: wasm-ld -mwasm64 --experimental-pic -shared -o %t.wasm %t.o
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# RUN: wasm-ld -mwasm64 --experimental-pic --unresolved-symbols=import-dynamic -shared -o %t.wasm %t.o
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# RUN: obj2yaml %t.wasm | FileCheck %s
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# RUN: llvm-objdump --disassemble-symbols=__wasm_call_ctors,__wasm_apply_data_relocs --no-show-raw-insn --no-leading-addr %t.wasm | FileCheck %s --check-prefixes DIS
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‎lld/test/wasm/signature-mismatch.s

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# RELOC-NEXT: - Index: 1
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# RELOC-NEXT: Kind: FUNCTION
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# RELOC-NEXT: Name: ret32
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# RELOC-NEXT: Flags: [ VISIBILITY_HIDDEN ]
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# RELOC-NEXT: Flags: [ ]
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# RELOC-NEXT: Function: 2
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# RELOC-NEXT: - Index: 2
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# RELOC-NEXT: Kind: DATA

‎lld/test/wasm/tag-section.ll

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; RUN: llc -filetype=obj -wasm-enable-eh -exception-model=wasm -mattr=+exception-handling -relocation-model=pic %p/Inputs/tag-section1.ll -o %t1.o
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; RUN: llc -filetype=obj -wasm-enable-eh -exception-model=wasm -mattr=+exception-handling -relocation-model=pic %p/Inputs/tag-section2.ll -o %t2.o
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; RUN: llc -filetype=obj -wasm-enable-eh -exception-model=wasm -mattr=+exception-handling -relocation-model=pic %s -o %t.o
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; RUN: wasm-ld --import-undefined --experimental-pic -pie -o %t.wasm %t.o %t1.o %t2.o
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; RUN: wasm-ld --import-undefined --experimental-pic --unresolved-symbols=import-dynamic -pie -o %t.wasm %t.o %t1.o %t2.o
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; RUN: obj2yaml %t.wasm | FileCheck %s --check-prefix=PIC
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target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"

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