diff options
| -rw-r--r-- | lld/ELF/Driver.cpp | 18 | ||||
| -rw-r--r-- | lld/test/ELF/as-needed-weak.s | 22 | ||||
| -rw-r--r-- | lld/test/ELF/gc-sections-shared.s | 72 |
3 files changed, 50 insertions, 62 deletions
diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp index 4bfef2f4f8e..c14d6d31000 100644 --- a/lld/ELF/Driver.cpp +++ b/lld/ELF/Driver.cpp @@ -1119,6 +1119,23 @@ 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) { + bool Used = S->Used; + replaceSymbol<Undefined>(S, nullptr, S->getName(), STB_WEAK, S->StOther, + S->Type); + S->Used = Used; + } + } + } +} + // 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) { @@ -1279,6 +1296,7 @@ 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..c0ebf403a33 100644 --- a/lld/test/ELF/gc-sections-shared.s +++ b/lld/test/ELF/gc-sections-shared.s @@ -25,6 +25,15 @@ # CHECK-NEXT: Section: Undefined (0x0) # 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: Symbol { # CHECK-NEXT: Name: bar # CHECK-NEXT: Value: # CHECK-NEXT: Size: @@ -51,15 +60,6 @@ # 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 @@ -68,59 +68,7 @@ # Test with %t.o at the end too. # RUN: ld.lld --gc-sections --export-dynamic-symbol foo -o %t --as-needed %t2.so %t3.so %t4.so %t.o -# RUN: llvm-readobj --dynamic-table --dyn-symbols %t | FileCheck --check-prefix=CHECK2 %s - -# CHECK2: DynamicSymbols [ -# CHECK2-NEXT: Symbol { -# CHECK2-NEXT: Name: -# CHECK2-NEXT: Value: -# CHECK2-NEXT: Size: -# CHECK2-NEXT: Binding: Local -# CHECK2-NEXT: Type: -# CHECK2-NEXT: Other: -# CHECK2-NEXT: Section: Undefined (0x0) -# CHECK2-NEXT: } -# CHECK2-NEXT: Symbol { -# CHECK2-NEXT: Name: bar -# CHECK2-NEXT: Value: -# CHECK2-NEXT: Size: -# CHECK2-NEXT: Binding: Global -# CHECK2-NEXT: Type: -# CHECK2-NEXT: Other: -# CHECK2-NEXT: Section: .text -# CHECK2-NEXT: } -# CHECK2-NEXT: Symbol { -# CHECK2-NEXT: Name: baz -# CHECK2-NEXT: Value: -# CHECK2-NEXT: Size: -# CHECK2-NEXT: Binding: Global -# CHECK2-NEXT: Type: -# CHECK2-NEXT: Other: -# 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: -# CHECK2-NEXT: Binding: Global -# CHECK2-NEXT: Type: -# CHECK2-NEXT: Other: -# CHECK2-NEXT: Section: .text -# CHECK2-NEXT: } -# CHECK2-NEXT: ] - -# CHECK2-NOT: NEEDED -# CHECK2: NEEDED Shared library: [{{.*}}3.so] -# CHECK2-NOT: NEEDED +# RUN: llvm-readobj --dynamic-table --dyn-symbols %t | FileCheck --check-prefix=CHECK %s .section .text.foo, "ax" .globl foo |
