47c5576d7d
If a global object is listed in `@llvm.used`, place it in a unique section with the `SHF_GNU_RETAIN` flag. The section is a GC root under `ld --gc-sections` with LLD>=13 or GNU ld>=2.36. For front ends which do not expect to see multiple sections of the same name, consider emitting `@llvm.compiler.used` instead of `@llvm.used`. SHF_GNU_RETAIN is restricted to ELFOSABI_GNU and ELFOSABI_FREEBSD in binutils. We don't do the restriction - see the rationale in D95749. The integrated assembler has supported SHF_GNU_RETAIN since D95730. GNU as>=2.36 supports section flag 'R'. We don't need to worry about GNU ld support because older GNU ld just ignores the unknown SHF_GNU_RETAIN. With this change, `__attribute__((retain))` functions/variables emitted by clang will get the SHF_GNU_RETAIN flag. Differential Revision: https://reviews.llvm.org/D97448
13 lines
486 B
LLVM
13 lines
486 B
LLVM
; RUN: llc -verify-machineinstrs -mtriple=powerpc-unknown-linux-gnu < %s | FileCheck %s
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; CHECK: .section .bss.X,"awR",@nobits
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; CHECK: .weak X
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; CHECK-LABEL: X:
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; CHECK: .long 0
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; CHECK: .size X, 4
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@X = weak global i32 0 ; <i32*> [#uses=1]
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@.str = internal constant [4 x i8] c"t.c\00", section "llvm.metadata" ; <[4 x i8]*> [#uses=1]
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@llvm.used = appending global [1 x i8*] [ i8* bitcast (i32* @X to i8*) ], section "llvm.metadata" ; <[1 x i8*]*> [#uses=0]
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