assert(TargetRegisterInfo::isVirtualRegister(Reg) &&
"Only makes sense for vregs");
+ // Ignore debug uses because debug info doesn't affect the code.
if (MRI->use_nodbg_empty(Reg))
return true;
- // Ignoring debug uses is necessary so debug info doesn't affect the code.
- // This may leave a referencing dbg_value in the original block, before
- // the definition of the vreg. Dwarf generator handles this although the
- // user might not get the right info at runtime.
-
// BreakPHIEdge is true if all the uses are in the successor MBB being sunken
// into and they are all PHI nodes. In this case, machine-sink must break
// the critical edge first. e.g.
for (MachineBasicBlock::succ_iterator SI = ParentBlock->succ_begin(),
E = ParentBlock->succ_end(); SI != E; ++SI) {
MachineBasicBlock *SuccBlock = *SI;
- // It is not possible to sink an instruction into its own block. This can
- // happen with loops.
- if (ParentBlock == SuccBlock)
- continue;
-
- // It's not safe to sink instructions to EH landing pad. Control flow into
- // landing pad is implicitly defined.
- if (SuccBlock->isLandingPad())
- continue;
-
bool LocalUse = false;
if (AllUsesDominatedByBlock(Reg, SuccBlock, ParentBlock,
BreakPHIEdge, LocalUse)) {
return NULL;
}
}
+
+ // It is not possible to sink an instruction into its own block. This can
+ // happen with loops.
+ if (ParentBlock == SuccToSinkTo)
+ return NULL;
+
+ // It's not safe to sink instructions to EH landing pad. Control flow into
+ // landing pad is implicitly defined.
+ if (SuccToSinkTo && SuccToSinkTo->isLandingPad())
+ return NULL;
+
return SuccToSinkTo;
}