diff --git a/lld/ELF/Symbols.h b/lld/ELF/Symbols.h --- a/lld/ELF/Symbols.h +++ b/lld/ELF/Symbols.h @@ -517,13 +517,16 @@ void Symbol::replace(const Symbol &newSym) { using llvm::ELF::STT_TLS; - // Symbols representing thread-local variables must be referenced by - // TLS-aware relocations, and non-TLS symbols must be reference by - // non-TLS relocations, so there's a clear distinction between TLS - // and non-TLS symbols. It is an error if the same symbol is defined - // as a TLS symbol in one file and as a non-TLS symbol in other file. - if (symbolKind != PlaceholderKind && !isLazy() && !newSym.isLazy() && - (type == STT_TLS) != (newSym.type == STT_TLS)) + // st_value of STT_TLS represents the assigned offset, not the actual address + // which is used by STT_FUNC and STT_OBJECT. STT_TLS symbols can only be + // referenced by special TLS relocations. It is usually an error if a STT_TLS + // symbol is replaced by a non-STT_TLS symbol, vice versa. There are two + // exceptions: (a) a STT_NOTYPE lazy/undefined symbol can be replaced by a + // STT_TLS symbol, (b) a STT_TLS undefined symbol can be replaced by a + // STT_NOTYPE lazy symbol. + if (symbolKind != PlaceholderKind && !newSym.isLazy() && + (type == STT_TLS) != (newSym.type == STT_TLS) && + type != llvm::ELF::STT_NOTYPE) error("TLS attribute mismatch: " + toString(*this) + "\n>>> defined in " + toString(newSym.file) + "\n>>> defined in " + toString(file)); diff --git a/lld/test/ELF/tls-mismatch.s b/lld/test/ELF/tls-mismatch.s --- a/lld/test/ELF/tls-mismatch.s +++ b/lld/test/ELF/tls-mismatch.s @@ -12,8 +12,10 @@ ## We fail to flag the swapped case. # RUN: ld.lld %t.o %t2.o -o /dev/null +## We fail to flag the STT_NOTYPE reference. This usually happens with hand-written +## assembly because compiler-generated code properly sets symbol types. # RUN: echo 'movq tls1,%rax' | llvm-mc -filetype=obj -triple=x86_64 - -o %t3.o -# RUN: not ld.lld %t3.o %t.o -o /dev/null 2>&1 | FileCheck %s +# RUN: ld.lld %t3.o %t.o -o /dev/null ## Overriding a TLS definition with a non-TLS definition does not make sense. # RUN: not ld.lld --defsym tls1=42 %t.o -o /dev/null 2>&1 | FileCheck %s @@ -21,11 +23,13 @@ ## Part of PR36049: This should probably be allowed. # RUN: not ld.lld --defsym tls1=tls2 %t.o -o /dev/null 2>&1 | FileCheck %s +## An undefined symbol in module-level inline assembly of a bitcode file +## is considered STT_NOTYPE. We should not error. # RUN: echo 'target triple = "x86_64-pc-linux-gnu" \ # RUN: target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" \ # RUN: module asm "movq tls1@GOTTPOFF(%rip), %rax"' | llvm-as - -o %t.bc # RUN: ld.lld %t.o %t.bc -o /dev/null -# RUN: not ld.lld %t.bc %t.o -o /dev/null 2>&1 | FileCheck %s +# RUN: ld.lld %t.bc %t.o -o /dev/null # CHECK: error: TLS attribute mismatch: tls1