llvm-project/lld/test/wasm/merge-string.s
Sam Clegg cd01430ff1 [lld][WebAssembly] Allow data symbols to extend past end of segment
This fixes a bug with string merging with string symbols that contain
NULLs, as is the case in the `merge-string.s` test.

The bug only showed when we run with `--relocatable` and then try read
the resulting object back in.  In this case we would end up with string
symbols that extend past the end of the segment in which they live.

The problem comes from the fact that sections which are flagged as
string mergable assume that all strings are NULL terminated.  The
merging algorithm will drop trailing chars that follow a NULL since they
are essentially unreachable.  However, the "size" attribute (in the
symbol table) of such a truncated symbol is not updated resulting a
symbol size that can overlap the end of the segment.

I verified that this can happen in ELF too given the right conditions
and the its harmless enough.  In practice Strings that contain embedded
null should not be part of a mergable section.

Differential Revision: https://reviews.llvm.org/D102281
2021-05-12 13:43:37 -07:00

102 lines
3.6 KiB
ArmAsm

// RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown %s -o %t.o
// RUN: wasm-ld -O1 %t.o -o %t.wasm --no-gc-sections --no-entry
// RUN: obj2yaml %t.wasm | FileCheck %s --check-prefixes=COMMON,MERGE
// Check that the default is the same as -O1 (since we default to -O1)
// RUN: wasm-ld %t.o -o %t.wasm --no-gc-sections --no-entry
// RUN: obj2yaml %t.wasm | FileCheck %s --check-prefixes=COMMON,MERGE
// Check that -O0 disables merging
// RUN: wasm-ld -O0 %t.o -o %t2.wasm --no-gc-sections --no-entry
// RUN: obj2yaml %t2.wasm | FileCheck --check-prefixes=COMMON,NOMERGE %s
// Check relocatable
// RUN: wasm-ld -r %t.o -o %t2.o
// RUN: obj2yaml %t2.o | FileCheck --check-prefixes=RELOC %s
.section .rodata1,"S",@
.asciz "abc"
foo:
.ascii "a"
.size foo, 1
bar:
.asciz "bc"
.asciz "bc"
.size bar, 6
.section .rodata_relocs,"",@
negative_addend:
.int32 foo-10
.size negative_addend, 4
.globl foo
.globl bar
.export_name foo, foo
.export_name bar, bar
// COMMON: - Type: GLOBAL
// COMMON-NEXT: Globals:
// COMMON-NEXT: - Index: 0
// COMMON-NEXT: Type: I32
// COMMON-NEXT: Mutable: true
// COMMON-NEXT: InitExpr:
// COMMON-NEXT: Opcode: I32_CONST
// COMMON-NEXT: Value: 66576
// COMMON-NEXT: - Index: 1
// COMMON-NEXT: Type: I32
// COMMON-NEXT: Mutable: false
// COMMON-NEXT: InitExpr:
// COMMON-NEXT: Opcode: I32_CONST
// MERGE-NEXT: Value: 1024
// NOMERGE-NEXT: Value: 1028
// COMMON-NEXT: - Index: 2
// COMMON-NEXT: Type: I32
// COMMON-NEXT: Mutable: false
// COMMON-NEXT: InitExpr:
// COMMON-NEXT: Opcode: I32_CONST
// MERGE-NEXT: Value: 1025
// NOMERGE-NEXT: Value: 1029
// COMMON-NEXT: - Type: EXPORT
// COMMON-NEXT: Exports:
// COMMON-NEXT: - Name: memory
// COMMON-NEXT: Kind: MEMORY
// COMMON-NEXT: Index: 0
// COMMON-NEXT: - Name: foo
// COMMON-NEXT: Kind: GLOBAL
// COMMON-NEXT: Index: 1
// COMMON-NEXT: - Name: bar
// COMMON-NEXT: Kind: GLOBAL
// COMMON-NEXT: Index: 2
//
// COMMON: - Type: DATA
// COMMON-NEXT: Segments:
// COMMON-NEXT: - SectionOffset: 7
// COMMON-NEXT: InitFlags: 0
// COMMON-NEXT: Offset:
// COMMON-NEXT: Opcode: I32_CONST
// COMMON-NEXT: Value: 1024
// MERGE-NEXT: Content: '61626300'
// NOMERGE-NEXT: Content: '6162630061626300626300'
// RELOC: - Type: DATA
// RELOC-NEXT: Relocations:
// RELOC-NEXT: - Type: R_WASM_MEMORY_ADDR_I32
// RELOC-NEXT: Index: 0
// RELOC-NEXT: Offset: 0xF
// RELOC-NEXT: Addend: -10
// RELOC-NEXT: Segments:
// RELOC-NEXT: - SectionOffset: 6
// RELOC-NEXT: InitFlags: 0
// RELOC-NEXT: Offset:
// RELOC-NEXT: Opcode: I32_CONST
// RELOC-NEXT: Value: 0
// RELOC-NEXT: Content: '61626300'
// RELOC-NEXT: - SectionOffset: 15
// RELOC-NEXT: InitFlags: 0
// RELOC-NEXT: Offset:
// RELOC-NEXT: Opcode: I32_CONST
// RELOC-NEXT: Value: 4
// RELOC-NEXT: Content: F6FFFFFF