maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

[ELF] Split too long X86_64TargetInfo::relaxGot method. NFC. 

Patch adds relaxGotNoPic() method to handle no-PIC path.

llvm-svn: 271506
This commit is contained in:
George Rimar 2016-06-02 09:22:00 +00:00
parent a9ba12d8b0
commit b720430b47
1 changed files with 49 additions and 41 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

90
lld/ELF/Target.cpp
View File

@ -120,6 +120,10 @@ public:
void relaxTlsGdToLe(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
void relaxTlsIeToLe(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
void relaxTlsLdToLe(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
private:
void relaxGotNoPic(uint8_t *Loc, uint64_t Val, uint8_t Op,
uint8_t ModRm) const;
};
class PPCTargetInfo final : public TargetInfo {
@ -760,47 +764,13 @@ RelExpr X86_64TargetInfo::adjustRelaxGotExpr(uint32_t Type, const uint8_t *Data,
return Config->Pic ? RelExpr : R_RELAX_GOT_PC_NOPIC;
}
void X86_64TargetInfo::relaxGot(uint8_t *Loc, uint64_t Val) const {
const uint8_t Op = Loc[-2];
const uint8_t ModRm = Loc[-1];
// Convert mov foo@GOTPCREL(%rip), %reg to lea foo(%rip), %reg.
if (Op == 0x8b) {
*(Loc - 2) = 0x8d;
relocateOne(Loc, R_X86_64_PC32, Val);
return;
}
// Convert call/jmp instructions.
if (Op == 0xff) {
if (ModRm == 0x15) {
// ABI says we can convert call *foo@GOTPCREL(%rip) to nop call foo.
// Instead we convert to addr32 call foo, where addr32 is instruction
// prefix. That makes result expression to be a single instruction.
*(Loc - 2) = 0x67; // addr32 prefix
*(Loc - 1) = 0xe8; // call
} else {
assert(ModRm == 0x25);
// Convert jmp *foo@GOTPCREL(%rip) to jmp foo nop.
// jmp doesn't return, so it is fine to use nop here, it is just a stub.
*(Loc - 2) = 0xe9; // jmp
*(Loc + 3) = 0x90; // nop
Loc -= 1;
Val += 1;
}
relocateOne(Loc, R_X86_64_PC32, Val);
return;
}
assert(!Config->Pic);
// We are relaxing a rip relative to an absolute, so compensate for the old
// -4 addend.
Val += 4;
// "Intel 64 and IA-32 Architectures Software Developer's Manual V2"
// (http://www.intel.com/content/dam/www/public/us/en/documents/manuals/
// 64-ia-32-architectures-software-developer-instruction-set-reference-manual-325383.pdf)
// can be used as reference.
// A subset of relaxations can only be applied for no-PIC. This method
// handles such relaxations. Instructions encoding information was taken from:
// "Intel 64 and IA-32 Architectures Software Developer's Manual V2"
// (http://www.intel.com/content/dam/www/public/us/en/documents/manuals/
// 64-ia-32-architectures-software-developer-instruction-set-reference-manual-325383.pdf)
void X86_64TargetInfo::relaxGotNoPic(uint8_t *Loc, uint64_t Val, uint8_t Op,
uint8_t ModRm) const {
const uint8_t Rex = Loc[-3];
// Convert "test %reg, foo@GOTPCREL(%rip)" to "test $foo, %reg".
if (Op == 0x85) {
@ -862,6 +832,44 @@ void X86_64TargetInfo::relaxGot(uint8_t *Loc, uint64_t Val) const {
relocateOne(Loc, R_X86_64_PC32, Val);
}
void X86_64TargetInfo::relaxGot(uint8_t *Loc, uint64_t Val) const {
const uint8_t Op = Loc[-2];
const uint8_t ModRm = Loc[-1];
// Convert mov foo@GOTPCREL(%rip), %reg to lea foo(%rip), %reg.
if (Op == 0x8b) {
*(Loc - 2) = 0x8d;
relocateOne(Loc, R_X86_64_PC32, Val);
return;
}
// Convert call/jmp instructions.
if (Op == 0xff) {
if (ModRm == 0x15) {
// ABI says we can convert call *foo@GOTPCREL(%rip) to nop call foo.
// Instead we convert to addr32 call foo, where addr32 is instruction
// prefix. That makes result expression to be a single instruction.
*(Loc - 2) = 0x67; // addr32 prefix
*(Loc - 1) = 0xe8; // call
} else {
assert(ModRm == 0x25);
// Convert jmp *foo@GOTPCREL(%rip) to jmp foo nop.
// jmp doesn't return, so it is fine to use nop here, it is just a stub.
*(Loc - 2) = 0xe9; // jmp
*(Loc + 3) = 0x90; // nop
Loc -= 1;
Val += 1;
}
relocateOne(Loc, R_X86_64_PC32, Val);
return;
}
assert(!Config->Pic);
// We are relaxing a rip relative to an absolute, so compensate
// for the old -4 addend.
relaxGotNoPic(Loc, Val + 4, Op, ModRm);
}
// Relocation masks following the #lo(value), #hi(value), #ha(value),
// #higher(value), #highera(value), #highest(value), and #highesta(value)
// macros defined in section 4.5.1. Relocation Types of the PPC-elf64abi