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[wasm] Simplify exceptional continuation in interpreter.

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This unifies how continuations after a control transfer are handled
within the interpreter loop. To avoid bumping the {pc} we can either
reset the opcode length to zero or just "continue" the loop. This just
unifies the approach for the entire {Execute} method.

R=clemensh@chromium.org

Change-Id: Ifc33c3a87cff69d417f61fa0bc234260c7fa502a
Reviewed-on: https://chromium-review.googlesource.com/c/1458216
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59434}
This commit is contained in:
Michael Starzinger 2019-02-07 12:33:37 +01:00 committed by Commit Bot
parent 4c65986a44
commit eb69c7da2c
1 changed files with 14 additions and 18 deletions
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32
src/wasm/wasm-interpreter.cc
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@ -1412,13 +1412,12 @@ class ThreadImpl {
}
void ReloadFromFrameOnException(Decoder* decoder, InterpreterCode** code,
pc_t* pc, pc_t* limit, int* len) {
pc_t* pc, pc_t* limit) {
Frame* top = &frames_.back();
*code = top->code;
*pc = top->pc;
*limit = top->code->end - top->code->start;
decoder->Reset(top->code->start, top->code->end);
*len = 0; // The {pc} has already been set correctly.
}
int LookupTargetDelta(InterpreterCode* code, pc_t pc) {
@ -2377,13 +2376,12 @@ class ThreadImpl {
#ifdef DEBUG
// Compute the stack effect of this opcode, and verify later that the
// stack was modified accordingly (unless an exception was thrown).
// stack was modified accordingly.
std::pair<uint32_t, uint32_t> stack_effect =
StackEffect(codemap_->module(), frames_.back().code->function->sig,
code->orig_start + pc, code->orig_end);
sp_t expected_new_stack_height =
StackHeight() - stack_effect.first + stack_effect.second;
bool exception_was_thrown = false;
#endif
switch (orig) {
@ -2424,15 +2422,15 @@ class ThreadImpl {
CommitPc(pc); // Needed for local unwinding.
const WasmException* exception = &module()->exceptions[imm.index];
if (!DoThrowException(exception, imm.index)) return;
ReloadFromFrameOnException(&decoder, &code, &pc, &limit, &len);
break;
ReloadFromFrameOnException(&decoder, &code, &pc, &limit);
continue; // Do not bump pc.
}
case kExprRethrow: {
WasmValue ex = Pop();
CommitPc(pc); // Needed for local unwinding.
if (!DoRethrowException(&ex)) return;
ReloadFromFrameOnException(&decoder, &code, &pc, &limit, &len);
break;
ReloadFromFrameOnException(&decoder, &code, &pc, &limit);
continue; // Do not bump pc.
}
case kExprSelect: {
WasmValue cond = Pop();
@ -2481,7 +2479,7 @@ class ThreadImpl {
size_t arity = code->function->sig->return_count();
if (!DoReturn(&decoder, &code, &pc, &limit, arity)) return;
PAUSE_IF_BREAK_FLAG(AfterReturn);
continue;
continue; // Do not bump pc.
}
case kExprUnreachable: {
return DoTrap(kTrapUnreachable, pc);
@ -2563,9 +2561,8 @@ class ThreadImpl {
case ExternalCallResult::EXTERNAL_UNWOUND:
return;
case ExternalCallResult::EXTERNAL_CAUGHT:
ReloadFromFrameOnException(&decoder, &code, &pc, &limit, &len);
DCHECK(exception_was_thrown = true);
break;
ReloadFromFrameOnException(&decoder, &code, &pc, &limit);
continue; // Do not bump pc.
}
if (result.type != ExternalCallResult::INTERNAL) break;
}
@ -2573,7 +2570,7 @@ class ThreadImpl {
if (!DoCall(&decoder, target, &pc, &limit)) return;
code = target;
PAUSE_IF_BREAK_FLAG(AfterCall);
continue; // don't bump pc
continue; // Do not bump pc.
} break;
case kExprCallIndirect: {
CallIndirectImmediate<Decoder::kNoValidate> imm(&decoder,
@ -2591,7 +2588,7 @@ class ThreadImpl {
return;
code = result.interpreter_code;
PAUSE_IF_BREAK_FLAG(AfterCall);
continue; // don't bump pc
continue; // Do not bump pc.
case ExternalCallResult::INVALID_FUNC:
return DoTrap(kTrapFuncInvalid, pc);
case ExternalCallResult::SIGNATURE_MISMATCH:
@ -2603,9 +2600,8 @@ class ThreadImpl {
case ExternalCallResult::EXTERNAL_UNWOUND:
return;
case ExternalCallResult::EXTERNAL_CAUGHT:
ReloadFromFrameOnException(&decoder, &code, &pc, &limit, &len);
DCHECK(exception_was_thrown = true);
break;
ReloadFromFrameOnException(&decoder, &code, &pc, &limit);
continue; // Do not bump pc.
}
} break;
case kExprGetGlobal: {
@ -2853,7 +2849,7 @@ class ThreadImpl {
}
#ifdef DEBUG
if (!WasmOpcodes::IsControlOpcode(opcode) && !exception_was_thrown) {
if (!WasmOpcodes::IsControlOpcode(opcode)) {
DCHECK_EQ(expected_new_stack_height, StackHeight());
}
#endif