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[OR1K] Add a dedicated PC register to register state. 

Before this commit, R9, the link register, was used as PC register.
However, a stack frame may have R9 not set to PC on entry, either
because it uses a custom calling convention, or, more likely,
because this is a signal or exception stack frame. Using R9 as
PC register made it impossible to unwind such frames.

All other architectures similarly use a dedicated PC register.

llvm-svn: 332512
This commit is contained in:
whitequark 2018-05-16 19:09:41 +00:00
parent 4de94930c3
commit 3f948cd79d
3 changed files with 12 additions and 7 deletions
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11
libunwind/src/Registers.hpp
View File

@ -2521,12 +2521,13 @@ public:
uint64_t getSP() const { return _registers.__r[1]; }
void setSP(uint32_t value) { _registers.__r[1] = value; }
uint64_t getIP() const { return _registers.__r[9]; }
void setIP(uint32_t value) { _registers.__r[9] = value; }
uint64_t getIP() const { return _registers.__pc; }
void setIP(uint32_t value) { _registers.__pc = value; }
private:
struct or1k_thread_state_t {
unsigned int __r[32];
unsigned int __r[32]; // r0-r31
unsigned int __pc; // Program counter
};
or1k_thread_state_t _registers;
@ -2561,7 +2562,7 @@ inline uint32_t Registers_or1k::getRegister(int regNum) const {
switch (regNum) {
case UNW_REG_IP:
return _registers.__r[9];
return _registers.__pc;
case UNW_REG_SP:
return _registers.__r[1];
}
@ -2576,7 +2577,7 @@ inline void Registers_or1k::setRegister(int regNum, uint32_t value) {
switch (regNum) {
case UNW_REG_IP:
_registers.__r[9] = value;
_registers.__pc = value;
return;
case UNW_REG_SP:
_registers.__r[1] = value;

6
libunwind/src/UnwindRegistersRestore.S
View File

@ -758,7 +758,7 @@ DEFINE_LIBUNWIND_PRIVATE_FUNCTION(_ZN9libunwind14Registers_or1k6jumptoEv)
# thread_state pointer is in r3
#
# restore integral registerrs
# restore integral registers
l.lwz r0, 0(r3)
l.lwz r1, 4(r3)
l.lwz r2, 8(r3)
@ -768,7 +768,7 @@ DEFINE_LIBUNWIND_PRIVATE_FUNCTION(_ZN9libunwind14Registers_or1k6jumptoEv)
l.lwz r6, 24(r3)
l.lwz r7, 28(r3)
l.lwz r8, 32(r3)
l.lwz r9, 36(r3)
# skip r9
l.lwz r10, 40(r3)
l.lwz r11, 44(r3)
l.lwz r12, 48(r3)
@ -795,6 +795,8 @@ DEFINE_LIBUNWIND_PRIVATE_FUNCTION(_ZN9libunwind14Registers_or1k6jumptoEv)
# at last, restore r3
l.lwz r3, 12(r3)
# load new pc into ra
l.lwz r9, 128(r3)
# jump to pc
l.jr r9
l.nop

2
libunwind/src/UnwindRegistersSave.S
View File

@ -938,6 +938,8 @@ DEFINE_LIBUNWIND_FUNCTION(unw_getcontext)
l.sw 116(r3), r29
l.sw 120(r3), r30
l.sw 124(r3), r31
# store ra to pc
l.sw 128(r3), r9
#endif
#endif /* !defined(__USING_SJLJ_EXCEPTIONS__) */