Implement minor branch optimization in executor (#806)

* minor optimization in executor * apply rustfmt * move utility methods into submodule
wasmi-labs · Nov 25, 2023 · 80e1d21 · 80e1d21
1 parent 834c3fb
commit 80e1d21
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Showing 2 changed files with 30 additions and 13 deletions.
diff --git a/crates/wasmi/src/engine/regmach/executor/instrs.rs b/crates/wasmi/src/engine/regmach/executor/instrs.rs
@@ -2,7 +2,7 @@ use self::{call::CallOutcome, return_::ReturnOutcome};
 use crate::{
     core::{TrapCode, UntypedValue},
     engine::{
-        bytecode::{BlockFuel, BranchOffset, FuncIdx},
+        bytecode::{BlockFuel, FuncIdx},
         cache::InstanceCache,
         config::FuelCosts,
         func_types::FuncTypeRegistry,
@@ -916,16 +916,6 @@ impl<'ctx, 'engine> Executor<'ctx, 'engine> {
         Ok(())
     }
 
-    /// Branches and adjusts the value stack.
-    ///
-    /// # Note
-    ///
-    /// Offsets the instruction pointer using the given [`BranchOffset`].
-    #[inline(always)]
-    fn branch_to(&mut self, offset: BranchOffset) {
-        self.ip.offset(offset.to_i32() as isize)
-    }
-
     /// Returns the [`ValueStackPtr`] of the [`CallFrame`].
     fn frame_stack_ptr(&mut self, frame: &CallFrame) -> ValueStackPtr {
         Self::frame_stack_ptr_impl(self.value_stack, frame)

diff --git a/crates/wasmi/src/engine/regmach/executor/instrs/branch.rs b/crates/wasmi/src/engine/regmach/executor/instrs/branch.rs
@@ -1,7 +1,14 @@
 use super::Executor;
 use crate::engine::{
     bytecode::BranchOffset,
-    regmach::bytecode::{BranchBinOpInstr, BranchBinOpInstrImm16, Const16, Const32, Register},
+    regmach::bytecode::{
+        BranchBinOpInstr,
+        BranchBinOpInstrImm16,
+        BranchOffset16,
+        Const16,
+        Const32,
+        Register,
+    },
 };
 use core::cmp;
 use wasmi_core::UntypedValue;
@@ -10,6 +17,26 @@ use wasmi_core::UntypedValue;
 use crate::engine::regmach::bytecode::Instruction;
 
 impl<'ctx, 'engine> Executor<'ctx, 'engine> {
+    /// Branches and adjusts the value stack.
+    ///
+    /// # Note
+    ///
+    /// Offsets the instruction pointer using the given [`BranchOffset`].
+    #[inline(always)]
+    fn branch_to(&mut self, offset: BranchOffset) {
+        self.ip.offset(offset.to_i32() as isize)
+    }
+
+    /// Branches and adjusts the value stack.
+    ///
+    /// # Note
+    ///
+    /// Offsets the instruction pointer using the given [`BranchOffset`].
+    #[inline(always)]
+    fn branch_to16(&mut self, offset: BranchOffset16) {
+        self.ip.offset(offset.to_i16() as isize)
+    }
+
     #[inline(always)]
     pub fn execute_branch(&mut self, offset: BranchOffset) {
         self.branch_to(offset)
@@ -47,7 +74,7 @@ impl<'ctx, 'engine> Executor<'ctx, 'engine> {
         let lhs: T = self.get_register_as(instr.lhs);
         let rhs = T::from(instr.rhs);
         if f(lhs, rhs) {
-            return self.branch_to(instr.offset.into());
+            return self.branch_to16(instr.offset);
         }
         self.next_instr()
     }