8ec1033933
`__cfstring` has embedded addends that foil ICF's hashing / equality checks. (We can ignore embedded addends when doing ICF because the same information gets recorded in our Reloc structs.) Therefore, in order to properly dedup CFStrings, we create a mutable copy of the CFString and zero out the embedded addends before performing any hashing / equality checks. (We did in fact have a partial implementation of CFString deduplication already. However, it only worked when the cstrings they point to are at identical offsets in their object files.) I anticipate this approach can be extended to other similar statically-allocated struct sections in the future. In addition, we previously treated all references with differing addends as unequal. This is not true when the references are to literals: different addends may point to the same literal in the output binary. In particular, `__cfstring` has such references to `__cstring`. I've adjusted ICF's `equalsConstant` logic accordingly, and I've added a few more tests to make sure the addend-comparison code path is adequately covered. Fixes https://github.com/llvm/llvm-project/issues/51281. Reviewed By: #lld-macho, Roger Differential Revision: https://reviews.llvm.org/D120137
151 lines
4.2 KiB
ArmAsm
151 lines
4.2 KiB
ArmAsm
# REQUIRES: x86
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# RUN: rm -rf %t; split-file %s %t
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# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/foo1.s -o %t/foo1.o
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# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/foo2.s -o %t/foo2.o
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# RUN: %lld -dylib --icf=all -framework CoreFoundation %t/foo1.o %t/foo2.o -o %t/foo
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# RUN: llvm-objdump --macho --rebase --bind --syms -d %t/foo | FileCheck %s
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# CHECK: (__TEXT,__text) section
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# CHECK-NEXT: _foo1:
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# CHECK-NEXT: _foo2:
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# CHECK-NEXT: movq _named_cfstring(%rip), %rax
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# CHECK-NEXT: _foo1_utf16:
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# CHECK-NEXT: movq [[#]](%rip), %rax
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# CHECK-NEXT: _named_foo1:
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# CHECK-NEXT: _named_foo2:
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# CHECK-NEXT: movq _named_cfstring(%rip), %rax
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# CHECK-NEXT: _foo2_utf16:
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# CHECK-NEXT: movq [[#]](%rip), %rax
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# CHECK: SYMBOL TABLE:
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# CHECK-DAG: [[#%.16x,FOO:]] g F __TEXT,__text _foo1
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# CHECK-DAG: [[#FOO]] g F __TEXT,__text _foo2
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## Make sure we don't emit redundant bind / rebase opcodes for folded sections.
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# CHECK: Rebase table:
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# CHECK-NEXT: segment section address type
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# CHECK-NEXT: __DATA_CONST __cfstring {{.*}} pointer
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# CHECK-NEXT: __DATA_CONST __cfstring {{.*}} pointer
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# CHECK-NEXT: __DATA_CONST __cfstring {{.*}} pointer
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# CHECK-EMPTY:
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# CHECK-NEXT: Bind table:
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# CHECK-NEXT: segment section address type addend dylib symbol
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# CHECK-NEXT: __DATA_CONST __cfstring {{.*}} pointer 0 CoreFoundation ___CFConstantStringClassReference
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# CHECK-NEXT: __DATA_CONST __cfstring {{.*}} pointer 0 CoreFoundation ___CFConstantStringClassReference
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# CHECK-NEXT: __DATA_CONST __cfstring {{.*}} pointer 0 CoreFoundation ___CFConstantStringClassReference
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# CHECK-EMPTY:
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#--- foo1.s
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.cstring
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L_.str.0:
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.asciz "bar"
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## This string is at a different offset than the corresponding "foo" string in
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## foo2.s. Make sure that we treat references to either string as equivalent.
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L_.str:
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.asciz "foo"
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.section __DATA,__cfstring
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.p2align 3
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L__unnamed_cfstring_:
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.quad ___CFConstantStringClassReference
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.long 1992 ## utf-8
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.space 4
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.quad L_.str
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.quad 3 ## strlen
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_named_cfstring:
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.quad ___CFConstantStringClassReference
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.long 1992 ## utf-8
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.space 4
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.quad L_.str
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.quad 3 ## strlen
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.section __TEXT,__ustring
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l_.ustr:
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.short 102 ## f
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.short 111 ## o
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.short 0 ## \0
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.short 111 ## o
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.short 0 ## \0
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## FIXME: We should be able to deduplicate UTF-16 CFStrings too.
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## Note that this string contains a null byte in the middle -- any dedup code
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## we add should take care to handle this correctly.
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## Technically, UTF-8 should support encoding null bytes too, but since we
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## atomize the __cstring section at every null byte, this isn't supported. ld64
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## doesn't support it either, and clang seems to always emit a UTF-16 CFString
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## if it needs to contain a null, so I think we're good here.
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.section __DATA,__cfstring
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.p2align 3
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L__unnamed_cfstring_.2:
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.quad ___CFConstantStringClassReference
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.long 2000 ## utf-16
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.space 4
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.quad l_.ustr
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.quad 4 ## strlen
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.text
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.globl _foo1, _foo1_utf16, _named_foo1
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_foo1:
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movq L__unnamed_cfstring_(%rip), %rax
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_foo1_utf16:
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movq L__unnamed_cfstring_.2(%rip), %rax
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_named_foo1:
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movq _named_cfstring(%rip), %rax
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.subsections_via_symbols
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#--- foo2.s
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.cstring
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L_.str:
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.asciz "foo"
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.section __DATA,__cfstring
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.p2align 3
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L__unnamed_cfstring_:
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.quad ___CFConstantStringClassReference
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.long 1992 ## utf-8
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.space 4
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.quad L_.str
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.quad 3 ## strlen
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_named_cfstring:
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.quad ___CFConstantStringClassReference
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.long 1992 ## utf-8
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.space 4
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.quad L_.str
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.quad 3 ## strlen
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.section __TEXT,__ustring
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.p2align 1
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l_.ustr:
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.short 102 ## f
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.short 111 ## o
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.short 0 ## \0
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.short 111 ## o
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.short 0 ## \0
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.section __DATA,__cfstring
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.p2align 3
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L__unnamed_cfstring_.2:
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.quad ___CFConstantStringClassReference
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.long 2000 ## utf-16
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.space 4
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.quad l_.ustr
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.quad 4 ## strlen
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.text
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.globl _foo2, _foo2_utf16, _named_foo2
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_foo2:
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movq L__unnamed_cfstring_(%rip), %rax
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_foo2_utf16:
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movq L__unnamed_cfstring_.2(%rip), %rax
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_named_foo2:
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movq _named_cfstring(%rip), %rax
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.subsections_via_symbols
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