7cc328600e
After 1af25a9860, we stop unconditionally
retaining wrapped symbols, which means that LTO's summary-based global
dead stripping can eliminate them even if they'll be referenced by a
linker script after the wrapping is performed. Mark symbols referenced
in linker scripts as `referenced` in addition to `isUsedInRegularObj`,
so that the wrapping logic correctly sets `referencedAfterWrap` for the
symbols which will be referenced after wrapping, which will prevent LTO
from eliminating them.
An alternative would have been to change the `referencedAfterWrap` logic
to look at `isUsedInRegularObj` in addition to `referenced`, but
`isUsedInRegularObj` is also set in other places (e.g. for the entry
symbol), and it's not clear that we want `referencedAfterWrap` to take
all those places into account, so it seemed better to keep that logic
as-is and instead set `referenced` for linker script-referenced symbols.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D124433
47 lines
1.7 KiB
LLVM
47 lines
1.7 KiB
LLVM
;; Verify that the target of a wrap is kept by LTO's summary-based global dead
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;; stripping if the original symbol is referenced by a linker script or --defsym
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; REQUIRES: x86
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; RUN: rm -rf %t && split-file %s %t
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;; We need a module summary to trigger summary-based global stripping
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; RUN: opt -module-summary -o %t/foo.bc %t/foo.ll
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; RUN: echo 'alias = __real_foo;' > %t/alias.script
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; RUN: ld.lld -shared -o %t/libalias_foo.so %t/foo.bc %t/alias.script --wrap foo
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; RUN: llvm-readelf --syms %t/libalias_foo.so | FileCheck --check-prefix=FOO %s
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; FOO: Symbol table '.symtab' contains
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; FOO-DAG: [[#]]: [[#%.16x,FOO_VAL:]] 1 FUNC LOCAL HIDDEN [[#]] foo
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; FOO-DAG: [[#]]: [[#FOO_VAL]] 0 FUNC GLOBAL DEFAULT [[#]] alias
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; RUN: opt -module-summary -o %t/wrap_foo.bc %t/wrap_foo.ll
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; RUN: ld.lld -shared -o %t/libalias_wrap_foo.so %t/wrap_foo.bc --wrap foo --defsym=alias=foo
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; RUN: llvm-readelf --syms %t/libalias_wrap_foo.so | FileCheck --check-prefix=WRAP-FOO %s
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; WRAP-FOO: Symbol table '.symtab' contains
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; WRAP-FOO-DAG: [[#]]: [[#%.16x,WRAP_FOO_VAL:]] 1 FUNC LOCAL HIDDEN [[#]] __wrap_foo
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; WRAP-FOO-DAG: [[#]]: [[#WRAP_FOO_VAL]] 0 FUNC GLOBAL DEFAULT [[#]] alias
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;--- foo.ll
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target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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define hidden void @foo() {
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ret void
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}
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;; We need a live root to trigger summary-based global stripping
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define dso_local void @bar() {
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ret void
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}
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;--- wrap_foo.ll
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target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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define hidden void @__wrap_foo() {
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ret void
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}
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define dso_local void @bar() {
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ret void
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}
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