9558456b53
On ELF, we place the metadata sections (`__sancov_guards`, `__sancov_cntrs`,
`__sancov_bools`, `__sancov_pcs` in section groups (either `comdat any` or
`comdat noduplicates`).
With `--gc-sections`, LLD since D96753 and GNU ld `-z start-stop-gc` may garbage
collect such sections. If all `__sancov_bools` are discarded, LLD will error
`error: undefined hidden symbol: __start___sancov_cntrs` (other sections are similar).
```
% cat a.c
void discarded() {}
% clang -fsanitize-coverage=func,trace-pc-guard -fpic -fvisibility=hidden a.c -shared -fuse-ld=lld -Wl,--gc-sections
...
ld.lld: error: undefined hidden symbol: __start___sancov_guards
>>> referenced by a.c
>>> /tmp/a-456662.o:(sancov.module_ctor_trace_pc_guard)
```
Use the `extern_weak` linkage (lowered to undefined weak symbols) to avoid the
undefined error.
Differential Revision: https://reviews.llvm.org/D98903
19 lines
1.2 KiB
LLVM
19 lines
1.2 KiB
LLVM
; Test -sanitizer-coverage-inline-8bit-counters=1
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; RUN: opt < %s -sancov -sanitizer-coverage-level=1 -sanitizer-coverage-inline-8bit-counters=1 -S -enable-new-pm=0 | FileCheck %s
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; RUN: opt < %s -passes='module(sancov-module)' -sanitizer-coverage-level=1 -sanitizer-coverage-inline-8bit-counters=1 -S | FileCheck %s
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; CHECK: @__sancov_gen_ = private global [1 x i8] zeroinitializer, section "__sancov_cntrs", comdat($foo), align 1
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; CHECK: @__start___sancov_cntrs = extern_weak hidden global i8
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; CHECK-NEXT: @__stop___sancov_cntrs = extern_weak hidden global i8
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target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
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target triple = "x86_64-unknown-linux-gnu"
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define void @foo() {
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entry:
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; CHECK: %0 = load i8, i8* getelementptr inbounds ([1 x i8], [1 x i8]* @__sancov_gen_, i64 0, i64 0), align 1, !nosanitize
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; CHECK: %1 = add i8 %0, 1
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; CHECK: store i8 %1, i8* getelementptr inbounds ([1 x i8], [1 x i8]* @__sancov_gen_, i64 0, i64 0), align 1, !nosanitize
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ret void
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}
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; CHECK: call void @__sanitizer_cov_8bit_counters_init(i8* @__start___sancov_cntrs, i8* @__stop___sancov_cntrs)
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