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llvm-mirror/test/Linker/comdat4.ll

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[Linker] Support weak symbols in nodeduplicate COMDAT group When a nodeduplicate COMDAT group contains a weak symbol, choose a non-weak symbol (or one of the weak ones) rather than reporting an error. This should address issue PR51394. With the current IR representation, a generic comdat nodeduplicate semantics is not representable for LTO. In the linker, sections and symbols are separate concepts. A dropped weak symbol does not force the defining input section to be dropped as well (though it can be collected by GC). In the IR, when a weak linkage symbol is dropped, its associate section content is dropped as well. For InstrProfiling, which is where ran into this issue in PR51394, the deduplication semantic is a sufficient workaround. Differential Revision: https://reviews.llvm.org/D108689
2021-09-01 08:10:30 +02:00
; RUN: split-file %s %t.dir
; RUN: not llvm-link %t.dir/global.ll %t.dir/global.ll -S -o - 2>&1 | FileCheck %s
; RUN: llvm-link %t.dir/global.ll %t.dir/weak.ll -S -o - 2>&1
; RUN: llvm-link %t.dir/weak.ll %t.dir/global.ll -S -o - 2>&1
; RUN: llvm-link %t.dir/weak.ll %t.dir/weak.ll -S -o - 2>&1
IR: Add COMDATs to the IR This new IR facility allows us to represent the object-file semantic of a COMDAT group. COMDATs allow us to tie together sections and make the inclusion of one dependent on another. This is required to implement features like MS ABI VFTables and optimizing away certain kinds of initialization in C++. This functionality is only representable in COFF and ELF, Mach-O has no similar mechanism. Differential Revision: http://reviews.llvm.org/D4178 llvm-svn: 211920
2014-06-27 20:19:56 +02:00
[Linker] Support weak symbols in nodeduplicate COMDAT group When a nodeduplicate COMDAT group contains a weak symbol, choose a non-weak symbol (or one of the weak ones) rather than reporting an error. This should address issue PR51394. With the current IR representation, a generic comdat nodeduplicate semantics is not representable for LTO. In the linker, sections and symbols are separate concepts. A dropped weak symbol does not force the defining input section to be dropped as well (though it can be collected by GC). In the IR, when a weak linkage symbol is dropped, its associate section content is dropped as well. For InstrProfiling, which is where ran into this issue in PR51394, the deduplication semantic is a sufficient workaround. Differential Revision: https://reviews.llvm.org/D108689
2021-09-01 08:10:30 +02:00
;--- global.ll
[IR] Rename `comdat noduplicates` to `comdat nodeduplicate` In the textual format, `noduplicates` means no COMDAT/section group deduplication is performed. Therefore, if both sets of sections are retained, and they happen to define strong external symbols with the same names, there will be a duplicate definition linker error. In PE/COFF, the selection kind lowers to `IMAGE_COMDAT_SELECT_NODUPLICATES`. The name describes the corollary instead of the immediate semantics. The name can cause confusion to other binary formats (ELF, wasm) which have implemented/ want to implement the "no deduplication" selection kind. Rename it to be clearer. Reviewed By: rnk Differential Revision: https://reviews.llvm.org/D106319
2021-07-20 21:47:10 +02:00
$foo = comdat nodeduplicate
Change the .ll syntax for comdats and add a syntactic sugar. In order to make comdats always explicit in the IR, we decided to make the syntax a bit more compact for the case of a GlobalObject in a comdat with the same name. Just dropping the $name causes problems for @foo = globabl i32 0, comdat $bar = comdat ... and declare void @foo() comdat $bar = comdat ... So the syntax is changed to @g1 = globabl i32 0, comdat($c1) @g2 = globabl i32 0, comdat and declare void @foo() comdat($c1) declare void @foo() comdat llvm-svn: 225302
2015-01-06 23:55:16 +01:00
@foo = global i64 43, comdat($foo)
[IR] Rename `comdat noduplicates` to `comdat nodeduplicate` In the textual format, `noduplicates` means no COMDAT/section group deduplication is performed. Therefore, if both sets of sections are retained, and they happen to define strong external symbols with the same names, there will be a duplicate definition linker error. In PE/COFF, the selection kind lowers to `IMAGE_COMDAT_SELECT_NODUPLICATES`. The name describes the corollary instead of the immediate semantics. The name can cause confusion to other binary formats (ELF, wasm) which have implemented/ want to implement the "no deduplication" selection kind. Rename it to be clearer. Reviewed By: rnk Differential Revision: https://reviews.llvm.org/D106319
2021-07-20 21:47:10 +02:00
; CHECK: Linking COMDATs named 'foo': nodeduplicate has been violated!
[Linker] Support weak symbols in nodeduplicate COMDAT group When a nodeduplicate COMDAT group contains a weak symbol, choose a non-weak symbol (or one of the weak ones) rather than reporting an error. This should address issue PR51394. With the current IR representation, a generic comdat nodeduplicate semantics is not representable for LTO. In the linker, sections and symbols are separate concepts. A dropped weak symbol does not force the defining input section to be dropped as well (though it can be collected by GC). In the IR, when a weak linkage symbol is dropped, its associate section content is dropped as well. For InstrProfiling, which is where ran into this issue in PR51394, the deduplication semantic is a sufficient workaround. Differential Revision: https://reviews.llvm.org/D108689
2021-09-01 08:10:30 +02:00
;--- weak.ll
$foo = comdat nodeduplicate
@foo = weak global i64 43, comdat($foo)
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