ART: Fix Quick-style LR vs PC core spill mask bug
It's always been a bug that Quick marked PC as spilled instead of
LR. The root cause was a mutation of the spill mask at frame exit,
when LR is being restored into PC to return. A local should have
been used to keep the actual spill mask safe and sound.
This has only worked because nobody ever uses LR, even after long
jumps for exception dispatch. However, single-frame deoptimization
needs this to work, and I'd rather fix this than being forced to
have machine-specific fixups.
Also fix in optimizing, and bump the oat version.
Change-Id: Ib032a533408bf464097fc96dcbfc5b6a68bf59a1
diff --git a/compiler/dex/quick/arm/call_arm.cc b/compiler/dex/quick/arm/call_arm.cc
index eb8730c..868d9a4 100644
--- a/compiler/dex/quick/arm/call_arm.cc
+++ b/compiler/dex/quick/arm/call_arm.cc
@@ -547,27 +547,28 @@
cfi_.RestoreMany(DwarfFpReg(0), fp_spill_mask_);
}
bool unspill_LR_to_PC = (core_spill_mask_ & (1 << rs_rARM_LR.GetRegNum())) != 0;
+ uint32_t core_unspill_mask = core_spill_mask_;
if (unspill_LR_to_PC) {
- core_spill_mask_ &= ~(1 << rs_rARM_LR.GetRegNum());
- core_spill_mask_ |= (1 << rs_rARM_PC.GetRegNum());
+ core_unspill_mask &= ~(1 << rs_rARM_LR.GetRegNum());
+ core_unspill_mask |= (1 << rs_rARM_PC.GetRegNum());
}
- if (core_spill_mask_ != 0u) {
- if ((core_spill_mask_ & ~(0xffu | (1u << rs_rARM_PC.GetRegNum()))) == 0u) {
+ if (core_unspill_mask != 0u) {
+ if ((core_unspill_mask & ~(0xffu | (1u << rs_rARM_PC.GetRegNum()))) == 0u) {
// Unspilling only low regs and/or PC, use 16-bit POP.
constexpr int pc_bit_shift = rs_rARM_PC.GetRegNum() - 8;
NewLIR1(kThumbPop,
- (core_spill_mask_ & ~(1u << rs_rARM_PC.GetRegNum())) |
- ((core_spill_mask_ & (1u << rs_rARM_PC.GetRegNum())) >> pc_bit_shift));
- } else if (IsPowerOfTwo(core_spill_mask_)) {
+ (core_unspill_mask & ~(1u << rs_rARM_PC.GetRegNum())) |
+ ((core_unspill_mask & (1u << rs_rARM_PC.GetRegNum())) >> pc_bit_shift));
+ } else if (IsPowerOfTwo(core_unspill_mask)) {
// kThumb2Pop cannot be used to unspill a single register.
- NewLIR1(kThumb2Pop1, CTZ(core_spill_mask_));
+ NewLIR1(kThumb2Pop1, CTZ(core_unspill_mask));
} else {
- NewLIR1(kThumb2Pop, core_spill_mask_);
+ NewLIR1(kThumb2Pop, core_unspill_mask);
}
// If we pop to PC, there is no further epilogue code.
if (!unspill_LR_to_PC) {
cfi_.AdjustCFAOffset(-num_core_spills_ * kArmPointerSize);
- cfi_.RestoreMany(DwarfCoreReg(0), core_spill_mask_);
+ cfi_.RestoreMany(DwarfCoreReg(0), core_unspill_mask);
DCHECK_EQ(cfi_.GetCurrentCFAOffset(), 0); // empty stack.
}
}