diff options
| -rw-r--r-- | lld/ELF/Driver.cpp | 13 | ||||
| -rw-r--r-- | lld/test/ELF/as-needed-weak.s | 22 | ||||
| -rw-r--r-- | lld/test/ELF/gc-sections-shared.s | 23 |
3 files changed, 35 insertions, 23 deletions
diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp index 539ef97a739..c380ee56b23 100644 --- a/lld/ELF/Driver.cpp +++ b/lld/ELF/Driver.cpp @@ -1059,6 +1059,18 @@ template <class ELFT> static void handleUndefined(StringRef Name) { Symtab->fetchLazy<ELFT>(Sym); } +// If all references to a DSO happen to be weak, the DSO is not added +// to DT_NEEDED. If that happens, we need to eliminate shared symbols +// created from the DSO. Otherwise, they become dangling references +// that point to a non-existent DSO. +template <class ELFT> static void demoteSharedSymbols() { + for (Symbol *Sym : Symtab->getSymbols()) + if (auto *S = dyn_cast<SharedSymbol>(Sym)) + if (!S->getFile<ELFT>().IsNeeded) + replaceSymbol<Undefined>(S, nullptr, S->getName(), STB_WEAK, S->StOther, + S->Type); +} + // Do actual linking. Note that when this function is called, // all linker scripts have already been parsed. template <class ELFT> void LinkerDriver::link(opt::InputArgList &Args) { @@ -1219,6 +1231,7 @@ template <class ELFT> void LinkerDriver::link(opt::InputArgList &Args) { // Do size optimizations: garbage collection, merging of SHF_MERGE sections // and identical code folding. markLive<ELFT>(); + demoteSharedSymbols<ELFT>(); decompressSections(); mergeSections(); if (Config->ICF) diff --git a/lld/test/ELF/as-needed-weak.s b/lld/test/ELF/as-needed-weak.s new file mode 100644 index 00000000000..f009c72d6f4 --- /dev/null +++ b/lld/test/ELF/as-needed-weak.s @@ -0,0 +1,22 @@ +# REQUIRES: x86 + +# RUN: echo '.globl foo; .type foo, @function; foo:' | \ +# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux - -o %t1.o +# RUN: ld.lld -shared -o %t1.so -soname libfoo %t1.o + +# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t2.o +# RUN: ld.lld -o %t.exe %t2.o --as-needed %t1.so +# RUN: llvm-readelf -dynamic-table -dyn-symbols %t.exe | FileCheck %s + +# CHECK-NOT: libfoo + +# CHECK: Symbol table of .hash for image: +# CHECK-NEXT: Num Buc: Value Size Type Bind Vis Ndx Name +# CHECK-NEXT: 1 1: 0000000000000000 0 FUNC WEAK DEFAULT UND foo@ + +.globl _start +.weak foo + +_start: + mov $foo, %eax + callq foo diff --git a/lld/test/ELF/gc-sections-shared.s b/lld/test/ELF/gc-sections-shared.s index 55b3ef556ce..408f5141bf2 100644 --- a/lld/test/ELF/gc-sections-shared.s +++ b/lld/test/ELF/gc-sections-shared.s @@ -9,11 +9,6 @@ # RUN: ld.lld --gc-sections --export-dynamic-symbol foo -o %t %t.o --as-needed %t2.so %t3.so %t4.so # RUN: llvm-readobj --dynamic-table --dyn-symbols %t | FileCheck %s -# This test the property that we have a needed line for every undefined. -# It would also be OK to keep bar2 and the need for %t2.so -# At the same time, weak symbols should not cause adding DT_NEEDED; -# this case is checked with symbol qux and %t4.so. - # CHECK: DynamicSymbols [ # CHECK-NEXT: Symbol { # CHECK-NEXT: Name: @@ -51,15 +46,6 @@ # CHECK-NEXT: Other: # CHECK-NEXT: Section: .text # CHECK-NEXT: } -# CHECK-NEXT: Symbol { -# CHECK-NEXT: Name: qux -# CHECK-NEXT: Value: -# CHECK-NEXT: Size: -# CHECK-NEXT: Binding: Weak -# CHECK-NEXT: Type: -# CHECK-NEXT: Other: -# CHECK-NEXT: Section: Undefined -# CHECK-NEXT: } # CHECK-NEXT: ] # CHECK-NOT: NEEDED @@ -99,15 +85,6 @@ # CHECK2-NEXT: Section: Undefined # CHECK2-NEXT: } # CHECK2-NEXT: Symbol { -# CHECK2-NEXT: Name: qux -# CHECK2-NEXT: Value: -# CHECK2-NEXT: Size: -# CHECK2-NEXT: Binding: Weak -# CHECK2-NEXT: Type: -# CHECK2-NEXT: Other: -# CHECK2-NEXT: Section: Undefined -# CHECK2-NEXT: } -# CHECK2-NEXT: Symbol { # CHECK2-NEXT: Name: foo # CHECK2-NEXT: Value: # CHECK2-NEXT: Size: |
