Fix exception handling during deoptimization

When interpreting a deoptimized shadow frame, we may start with a
pending exception thrown by a previous deoptimized shadow frame (from
a previous invoke). Therefore, we need to handle it before executing
any instruction, otherwise we execute incorrect code.

Because we need the DEX pc of the throwing instruction to find a
matching catch handler, we initialize deoptimized shadow frames with
the current DEX pc at the time the stack is deoptimized.
When we are about to interpret a deoptimized shadow frame, we need to
update the shadow frame with the DEX pc of the next instruction to
interpret. There are three cases:
- if there is no pending exception, this is the instruction following
the current one.
- if there is a pending exception and we found a matching catch
handler, this is the first instruction of this handler.
- if there is a pending exception but there is no matching catch
handler, we do not execute the deoptimized shadow frame and continue
to its caller.

The verifier now fails when a method starts with a move-exception
instruction. Indeed we cannot start executing a method with a pending
exception.

Bug: 19057915
Bug: 19041195
Bug: 18607595
Change-Id: I355ac81e6ac098edc7e3cc8c13dbfa24a2969ab2

1 files changed, 1 insertions, 3 deletions

diff --git a/runtime/quick_exception_handler.cc b/runtime/quick_exception_handler.cc
index 3517848927..34f6713d70 100644
--- a/runtime/quick_exception_handler.cc
+++ b/runtime/quick_exception_handler.cc
@@ -204,9 +204,7 @@ class DeoptimizeStackVisitor FINAL : public StackVisitor {
     CHECK(code_item != nullptr);
     uint16_t num_regs = code_item->registers_size_;
     uint32_t dex_pc = GetDexPc();
-    const Instruction* inst = Instruction::At(code_item->insns_ + dex_pc);
-    uint32_t new_dex_pc = dex_pc + inst->SizeInCodeUnits();
-    ShadowFrame* new_frame = ShadowFrame::Create(num_regs, nullptr, m, new_dex_pc);
+    ShadowFrame* new_frame = ShadowFrame::Create(num_regs, nullptr, m, dex_pc);
     StackHandleScope<3> hs(self_);
     mirror::Class* declaring_class = m->GetDeclaringClass();
     Handle<mirror::DexCache> h_dex_cache(hs.NewHandle(declaring_class->GetDexCache()));