[ELF][MIPS] Don't emit dynamic relocations for PIE non-preemptible TLS

Whilst not wrong (unless using static PIE where the relocations are
likely not implemented by the runtime), this is inefficient, as the TLS
module indices and offsets are independent of the executable's load
address.

Reviewed By: MaskRay, atanasyan

Differential Revision: https://reviews.llvm.org/D101382

diff --git a/lld/ELF/SyntheticSections.cpp b/lld/ELF/SyntheticSections.cpp
index cd81aa6..818bbdd 100644 (file)
--- a/lld/ELF/SyntheticSections.cpp
+++ b/lld/ELF/SyntheticSections.cpp
@@ -1005,7 +1005,7 @@ void MipsGotSection::build() {
       Symbol *s = p.first;
       uint64_t offset = p.second * config->wordsize;
       if (s == nullptr) {
-        if (!config->isPic)
+        if (!config->shared)
           continue;
         mainPart->relaDyn->addReloc(target->tlsModuleIndexRel, this, offset, s);
       } else {
@@ -1013,7 +1013,7 @@ void MipsGotSection::build() {
         // for the module index. Therefore only checking for
         // S->isPreemptible is not sufficient (this happens e.g. for
         // thread-locals that have been marked as local through a linker script)
-        if (!s->isPreemptible && !config->isPic)
+        if (!s->isPreemptible && !config->shared)
           continue;
         mainPart->relaDyn->addReloc(target->tlsModuleIndexRel, this, offset, s);
         // However, we can skip writing the TLS offset reloc for non-preemptible
@@ -1119,13 +1119,13 @@ void MipsGotSection::writeTo(uint8_t *buf) {
     for (const std::pair<Symbol *, size_t> &p : g.tls)
       write(p.second, p.first, p.first->isPreemptible ? 0 : -0x7000);
     for (const std::pair<Symbol *, size_t> &p : g.dynTlsSymbols) {
-      if (p.first == nullptr && !config->isPic)
+      if (p.first == nullptr && !config->shared)
         write(p.second, nullptr, 1);
       else if (p.first && !p.first->isPreemptible) {
-        // If we are emitting PIC code with relocations we mustn't write
+        // If we are emitting a shared libary with relocations we mustn't write
         // anything to the GOT here. When using Elf_Rel relocations the value
         // one will be treated as an addend and will cause crashes at runtime
-        if (!config->isPic)
+        if (!config->shared)
           write(p.second, nullptr, 1);
         write(p.second + 1, p.first, -0x8000);
       }

diff --git a/lld/test/ELF/mips-tls-64.s b/lld/test/ELF/mips-tls-64.s
index a3657ce..5f22156 100644 (file)
--- a/lld/test/ELF/mips-tls-64.s
+++ b/lld/test/ELF/mips-tls-64.s
@@ -16,6 +16,11 @@
 # RUN:   | FileCheck -check-prefix=DIS %s
 # RUN: llvm-readobj -r -A %t.exe | FileCheck %s
 
+# RUN: ld.lld -pie %t.o %t.so -script %t.script -o %t.pie
+# RUN: llvm-objdump -d -s -t --no-show-raw-insn %t.pie \
+# RUN:   | FileCheck -check-prefix=DIS %s
+# RUN: llvm-readobj -r -A %t.pie | FileCheck %s
+
 # RUN: ld.lld -shared %t.o %t.so -script %t.script -o %t-out.so
 # RUN: llvm-objdump -d -s -t --no-show-raw-insn %t-out.so \
 # RUN:   | FileCheck -check-prefix=DIS-SO %s

diff --git a/lld/test/ELF/mips-tls.s b/lld/test/ELF/mips-tls.s
index 4463ec1..4976ec3 100644 (file)
--- a/lld/test/ELF/mips-tls.s
+++ b/lld/test/ELF/mips-tls.s
@@ -16,6 +16,11 @@
 # RUN:   | FileCheck -check-prefix=DIS %s
 # RUN: llvm-readobj -r -A %t.exe | FileCheck %s
 
+# RUN: ld.lld -pie %t.o %t.so -script %t.script -o %t.pie
+# RUN: llvm-objdump -d -s -t --no-show-raw-insn %t.pie \
+# RUN:   | FileCheck -check-prefix=DIS %s
+# RUN: llvm-readobj -r -A %t.pie | FileCheck %s
+
 # RUN: ld.lld -shared %t.o %t.so -script %t.script -o %t-out.so
 # RUN: llvm-objdump -d -s -t --no-show-raw-insn %t-out.so \
 # RUN:   | FileCheck -check-prefix=DIS-SO %s