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This is a case missed by D64136. If %t1.o has a weak reference on foo, and %t2.so has a non-weak reference on foo: ``` 0. ld.lld %t1.o %t2.so # ok; STB_WEAK; accepted since D64136 1. ld.lld %t2.so %t1.o # undefined symbol: foo; STB_GLOBAL 2. gold %t1.o %t2.so # ok; STB_WEAK 3. gold %t2.so %t1.o # undefined reference to 'foo'; STB_GLOBAL 4. ld.bfd %t1.o %t2.so # undefined reference to `foo'; STB_WEAK 5. ld.bfd %t2.so %t1.o # undefined reference to `foo'; STB_WEAK ``` It can be argued that in both cases, the binding of the undefined foo should be set to STB_WEAK, because the binding should not be affected by referenced from shared objects. --allow-shlib-undefined doesn't suppress errors (3,4,5), but -shared or --noinhibit-exec allows ld.bfd/gold to produce a binary: ``` 3. gold -shared %t2.so %t1.o # ok; STB_GLOBAL 4. ld.bfd -shared %t2.so %t1.o # ok; STB_WEAK 5. ld.bfd -shared %t1.o %t1.o # ok; STB_WEAK ``` If %t2.so has DT_NEEDED entries, ld.bfd will load them (lld/gold don't have the behavior). If one of the DSO defines foo and it is in the link-time search path (e.g. DT_NEEDED entry is an absolute path, via -rpath=, via -rpath-link=, etc), `ld.bfd %t1.o %t2.so` and `ld.bfd %t1.o %t2.so` will not error. In this patch, we make Undefined and SharedSymbol share the same binding computing logic. Case 1 will be allowed: ``` 0. ld.lld %t1.o %t2.so # ok; STB_WEAK; accepted since D64136 1. ld.lld %t2.so %t1.o # ok; STB_WEAK; changed by this patch ``` In the future, we can explore the option that turns both (0,1) into errors if --no-allow-shlib-undefined (default when linking an executable) is in action. Reviewed By: ruiu Differential Revision: https://reviews.llvm.org/D65584 llvm-svn: 368038
41 lines
1.6 KiB
ArmAsm
41 lines
1.6 KiB
ArmAsm
# REQUIRES: x86
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# RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t.o
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# RUN: ld.lld -shared %t.o -o %t.so
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# RUN: echo '.data; .weak foo; .quad foo' | llvm-mc -filetype=obj -triple=x86_64 - -o %t1.o
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# RUN: echo '.data; .quad foo' | llvm-mc -filetype=obj -triple=x86_64 - -o %t2.o
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# RUN: ld.lld -shared %t2.o -o %t2.so
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## If the first undefined reference is weak, the binding changes to
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## STB_WEAK.
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# RUN: ld.lld %t1.o %t.so -o %t
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# RUN: llvm-readelf --dyn-syms %t | FileCheck --check-prefix=WEAK %s
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# RUN: ld.lld %t.so %t1.o -o %t
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# RUN: llvm-readelf --dyn-syms %t | FileCheck --check-prefix=WEAK %s
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## The binding remains STB_WEAK if there is no STB_GLOBAL undefined reference.
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# RUN: ld.lld %t1.o %t.so %t1.o -o %t
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# RUN: llvm-readelf --dyn-syms %t | FileCheck --check-prefix=WEAK %s
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# RUN: ld.lld %t.so %t1.o %t1.o -o %t
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# RUN: llvm-readelf --dyn-syms %t | FileCheck --check-prefix=WEAK %s
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## The binding changes back to STB_GLOBAL if there is a STB_GLOBAL undefined reference.
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# RUN: ld.lld %t1.o %t.so %t2.o -o %t
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# RUN: llvm-readelf --dyn-syms %t | FileCheck --check-prefix=GLOBAL %s
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# RUN: ld.lld %t2.o %t.so %t1.o -o %t
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# RUN: llvm-readelf --dyn-syms %t | FileCheck --check-prefix=GLOBAL %s
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## Check the binding (weak) is not affected by the STB_GLOBAL undefined
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## reference in %t2.so
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# RUN: ld.lld %t1.o %t2.so -o %t
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# RUN: llvm-readelf --dyn-syms %t | FileCheck --check-prefix=WEAK %s
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# RUN: ld.lld %t2.so %t1.o -o %t
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# RUN: llvm-readelf --dyn-syms %t | FileCheck --check-prefix=WEAK %s
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# WEAK: NOTYPE WEAK DEFAULT UND foo
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# GLOBAL: NOTYPE GLOBAL DEFAULT UND foo
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.globl foo
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foo:
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