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Lockstep: match the native block's loop-exit point, not the first arrival #4

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Lockstep: match the native block's loop-exit point, not the first arrival #4

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11 changes: 10 additions & 1 deletion Source/Core/Core/PowerPC/StaticRecomp/StaticRecompLockstep_Check.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -184,7 +184,16 @@ void StaticRecompLockstepVerifier::LockstepCheck(u32 entry_pc, u32 end_pc, const
// must execute the inlined iteration before stopping. An arrival by any
// branch (including a call to an address which also happens to be a loop
// header) is already the native dispatch boundary.
if (!end_is_loop_header || before + 4u != end_pc)
// ...and on a loop header, not until the shadow has done as much work as
// the native block did. A generated chunk leaves an inlined loop at its
// header once the block's charge crosses DOLRECOMP_C_LOOP_CYCLE_BUDGET
// (emitter.c:324), so the iteration it stops on is timing-determined and
// cannot be inferred from the code. Stopping at the first branch arrival
// compares two different iterations of the same loop at the same PC,
// which is the long-standing GPR divergence on both arm64 and x86-64.
if (!end_is_loop_header)
break;
if (interp_cycles >= native_charge)
break;
}
if (ppc.Exceptions != 0)
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