ba3c1f9ce3
In WebAssembly, we have `WASM_SYMBOL_NO_STRIP` symbol flag to mark the referenced content as retained. However, the flag is not enough to express retained data that is not referenced by any symbol. This patch adds a new segment flag`WASM_SEG_FLAG_RETAIN` to support "private" linkage data that is retained by llvm.used. This kind of data that is not referenced but must be retained is usually used with encapsulation symbols (__start/__stop). Swift runtime uses this technique and depends on the fact "all metadata sections in live objects are retained", which was not guaranteed with `--gc-sections` before this patch. This is a revised version of https://reviews.llvm.org/D126950 (has been reverted) based on @MaskRay's comments
23 lines
691 B
LLVM
23 lines
691 B
LLVM
; RUN: llc < %s --mtriple=wasm32-unknown-unknown | FileCheck %s
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@llvm.used = appending global [
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5 x ptr
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] [
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ptr @ga, ptr @gb, ptr @gc, ptr @gd, ptr @ge
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], section "llvm.metadata"
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; CHECK: .section .data.ga,"R",@
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@ga = global i32 42
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; CHECK: .section .data.gb,"R",@
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@gb = internal global i32 41
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; CHECK: .section .data..Lgc,"R",@
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@gc = private global i32 40
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; CHECK: .section .rodata.gd,"R",@
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@gd = constant i32 39
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; All sections with the same explicit name are flagged as retained if a part of them is retained.
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; CHECK: .section dddd,"R",@
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@ge = global i32 38, section "dddd"
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; CHECK: .section dddd,"R",@
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@gg = global i32 37, section "dddd"
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