Avoid updating instr_ptr for tail calls (#785)

avoid updating instr_ptr for tail calls This avoids updating the instruction pointer of the current call frame upon a tail call since this call frame is going to be discarded upon a tail call.
wasmi-labs · Nov 13, 2023 · 194359f · 194359f
1 parent b7a3ef4
commit 194359f
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Showing 2 changed files with 2 additions and 11 deletions.
diff --git a/crates/wasmi/src/engine/executor.rs b/crates/wasmi/src/engine/executor.rs
@@ -606,9 +606,9 @@ impl<'ctx, 'engine> Executor<'ctx, 'engine> {
         func: &Func,
         kind: CallKind,
     ) -> Result<CallOutcome, TrapCode> {
-        self.next_instr_at(skip);
         self.sync_stack_ptr();
         if matches!(kind, CallKind::Nested) {
+            self.next_instr_at(skip);
             self.call_stack
                 .push(FuncFrame::new(self.ip, self.cache.instance()))?;
         }
@@ -638,12 +638,9 @@ impl<'ctx, 'engine> Executor<'ctx, 'engine> {
     /// with the outer structures.
     #[inline(always)]
     fn call_func_internal(&mut self, func: CompiledFunc, kind: CallKind) -> Result<(), TrapCode> {
-        self.next_instr_at(match kind {
-            CallKind::Nested => 1,
-            CallKind::Tail => 2,
-        });
         self.sync_stack_ptr();
         if matches!(kind, CallKind::Nested) {
+            self.next_instr_at(1);
             self.call_stack
                 .push(FuncFrame::new(self.ip, self.cache.instance()))?;
         }

diff --git a/crates/wasmi/src/engine/regmach/executor/instrs/call.rs b/crates/wasmi/src/engine/regmach/executor/instrs/call.rs
@@ -190,7 +190,6 @@ impl<'ctx, 'engine> Executor<'ctx, 'engine> {
     /// Executes an [`Instruction::ReturnCallInternal0`].
     #[inline(always)]
     pub fn execute_return_call_internal_0(&mut self, func: CompiledFunc) -> Result<(), TrapCode> {
-        self.update_instr_ptr_at(1);
         self.execute_return_call_internal_impl(func, None)?;
         Ok(())
     }
@@ -199,7 +198,6 @@ impl<'ctx, 'engine> Executor<'ctx, 'engine> {
     #[inline(always)]
     pub fn execute_return_call_internal(&mut self, func: CompiledFunc) -> Result<(), TrapCode> {
         let call_params = self.fetch_call_params(1);
-        self.update_instr_ptr_at(2);
         self.execute_return_call_internal_impl(func, Some(&call_params))?;
         Ok(())
     }
@@ -262,7 +260,6 @@ impl<'ctx, 'engine> Executor<'ctx, 'engine> {
         func: FuncIdx,
     ) -> Result<CallOutcome, TrapCode> {
         let func = self.cache.get_func(self.ctx, func);
-        self.update_instr_ptr_at(1);
         self.execute_return_call_imported_impl(&func, None)
     }
 
@@ -271,7 +268,6 @@ impl<'ctx, 'engine> Executor<'ctx, 'engine> {
     pub fn execute_return_call_imported(&mut self, func: FuncIdx) -> Result<CallOutcome, TrapCode> {
         let call_params = self.fetch_call_params(1);
         let func = self.cache.get_func(self.ctx, func);
-        self.update_instr_ptr_at(2);
         self.execute_return_call_imported_impl(&func, Some(&call_params))
     }
 
@@ -346,7 +342,6 @@ impl<'ctx, 'engine> Executor<'ctx, 'engine> {
         func_type: SignatureIdx,
     ) -> Result<CallOutcome, TrapCode> {
         let call_indirect_params = self.fetch_call_indirect_params(1);
-        self.update_instr_ptr_at(2);
         let results = self.caller_results();
         self.execute_call_indirect_impl(
             results,
@@ -365,7 +360,6 @@ impl<'ctx, 'engine> Executor<'ctx, 'engine> {
     ) -> Result<CallOutcome, TrapCode> {
         let call_indirect_params = self.fetch_call_indirect_params(1);
         let call_params = self.fetch_call_params(2);
-        self.update_instr_ptr_at(3);
         let results = self.caller_results();
         self.execute_call_indirect_impl(
             results,