Author: atanasyan
Date: Thu Jan 14 14:42:09 2016
New Revision: 257798
URL: http://llvm.org/viewvc/llvm-project?rev=257798&view=rev
Log:
[ELF][MIPS] Ignore 'hint' relocations like R_MIPS_JALR in the `scanRelocs` method
MIPS ABI has relocations like R_MIPS_JALR which is just a hint for
linker to make some code optimization. Such relocations should not be
handled as a regular ones and lead to say dynamic relocation creation.
The patch introduces new virtual `Target::isHintReloc` method, overrides
it in the `MipsTargetInfo` class and calls it in the `Writer<ELFT>::scanRelocs`
method.
Differential Revision: http://reviews.llvm.org/D16193
Modified:
lld/trunk/ELF/Target.cpp
lld/trunk/ELF/Target.h
lld/trunk/ELF/Writer.cpp
lld/trunk/test/ELF/mips-jalr.test
Modified: lld/trunk/ELF/Target.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Target.cpp?rev=257798&r1=257797&r2=257798&view=diff
==============================================================================
--- lld/trunk/ELF/Target.cpp (original)
+++ lld/trunk/ELF/Target.cpp Thu Jan 14 14:42:09 2016
@@ -239,6 +239,7 @@ public:
void relocateOne(uint8_t *Loc, uint8_t *BufEnd, uint32_t Type, uint64_t P,
uint64_t SA, uint64_t ZA = 0,
uint8_t *PairedLoc = nullptr) const override;
+ bool isHintReloc(uint32_t Type) const override;
bool isRelRelative(uint32_t Type) const override;
};
} // anonymous namespace
@@ -284,6 +285,8 @@ bool TargetInfo::needsCopyRel(uint32_t T
bool TargetInfo::isGotRelative(uint32_t Type) const { return false; }
+bool TargetInfo::isHintReloc(uint32_t Type) const { return false; }
+
bool TargetInfo::isRelRelative(uint32_t Type) const { return true; }
bool TargetInfo::isSizeReloc(uint32_t Type) const { return false; }
@@ -1581,6 +1584,11 @@ void MipsTargetInfo<ELFT>::relocateOne(u
}
template <class ELFT>
+bool MipsTargetInfo<ELFT>::isHintReloc(uint32_t Type) const {
+ return Type == R_MIPS_JALR;
+}
+
+template <class ELFT>
bool MipsTargetInfo<ELFT>::isRelRelative(uint32_t Type) const {
switch (Type) {
default:
Modified: lld/trunk/ELF/Target.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Target.h?rev=257798&r1=257797&r2=257798&view=diff
==============================================================================
--- lld/trunk/ELF/Target.h (original)
+++ lld/trunk/ELF/Target.h Thu Jan 14 14:42:09 2016
@@ -57,6 +57,11 @@ public:
uint64_t GotEntryAddr, uint64_t PltEntryAddr,
int32_t Index, unsigned RelOff) const = 0;
+ // Returns true if a relocation is just a hint for linker to make for example
+ // some code optimization. Such relocations should not be handled as a regular
+ // ones and lead to dynamic relocation creation etc.
+ virtual bool isHintReloc(uint32_t Type) const;
+
// Returns true if a relocation is relative to the place being relocated,
// such as relocations used for PC-relative instructions. Such relocations
// need not be fixed up if an image is loaded to a different address than
Modified: lld/trunk/ELF/Writer.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Writer.cpp?rev=257798&r1=257797&r2=257798&view=diff
==============================================================================
--- lld/trunk/ELF/Writer.cpp (original)
+++ lld/trunk/ELF/Writer.cpp Thu Jan 14 14:42:09 2016
@@ -210,6 +210,10 @@ void Writer<ELFT>::scanRelocs(
SymbolBody *Body = File.getSymbolBody(SymIndex);
uint32_t Type = RI.getType(Config->Mips64EL);
+ // Ignore "hint" relocation because it is for optional code optimization.
+ if (Target->isHintReloc(Type))
+ continue;
+
if (Target->isGotRelative(Type))
HasGotOffRel = true;
Modified: lld/trunk/test/ELF/mips-jalr.test
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/mips-jalr.test?rev=257798&r1=257797&r2=257798&view=diff
==============================================================================
--- lld/trunk/test/ELF/mips-jalr.test (original)
+++ lld/trunk/test/ELF/mips-jalr.test Thu Jan 14 14:42:09 2016
@@ -3,11 +3,15 @@
# RUN: yaml2obj -format elf %s -o %t.o
# RUN: ld.lld %t.o -o %t.so -shared
# RUN: llvm-objdump -d %t.so | FileCheck %s
+# RUN: llvm-readobj -relocations %t.so | FileCheck -check-prefix=REL %s
# REQUIRES: mips
# CHECK: 10000: 09 f8 20 03 jalr $25
+# REL: Relocations [
+# REL-NEXT: ]
+
FileHeader:
Class: ELFCLASS32
Data: ELFDATA2LSB