From 60b555107f30b739c55ed43eaaf83bc0f19dde63 Mon Sep 17 00:00:00 2001
From: Fabian <copy@copy.sh>
Date: Fri, 4 Nov 2022 18:36:30 -0600
Subject: [PATCH] identify add for the purpose of optimising conditions

---
 src/rust/codegen.rs          | 12 +++++++++---
 src/rust/jit.rs              |  5 +++++
 src/rust/jit_instructions.rs | 16 ++++++++++++++--
 3 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/src/rust/codegen.rs b/src/rust/codegen.rs
index 0ff037a9..ff245e86 100644
--- a/src/rust/codegen.rs
+++ b/src/rust/codegen.rs
@@ -340,7 +340,12 @@ fn gen_get_flags_changed(builder: &mut WasmBuilder) {
 }
 fn gen_get_last_result(builder: &mut WasmBuilder, previous_instruction: &Instruction) {
     match previous_instruction {
-        Instruction::Sub {
+        Instruction::Add {
+            dest: InstructionOperandDest::WasmLocal(l),
+            opsize: OPSIZE_32,
+            ..
+        }
+        | Instruction::Sub {
             dest: InstructionOperandDest::WasmLocal(l),
             opsize: OPSIZE_32,
             ..
@@ -1630,7 +1635,7 @@ pub fn gen_getzf(ctx: &mut JitContext, negate: ConditionNegate) {
                 }
             }
         },
-        Instruction::Cmp { .. } | Instruction::Sub { .. } => {
+        Instruction::Cmp { .. } | Instruction::Sub { .. } | Instruction::Add { .. } => {
             gen_profiler_stat_increment(ctx.builder, profiler::stat::CONDITION_OPTIMISED);
             gen_get_last_result(ctx.builder, &ctx.previous_instruction);
             if negate == ConditionNegate::False {
@@ -1757,6 +1762,7 @@ pub fn gen_getsf(ctx: &mut JitContext, negate: ConditionNegate) {
     match &ctx.previous_instruction {
         Instruction::Cmp { opsize, .. }
         | Instruction::Sub { opsize, .. }
+        | Instruction::Add { opsize, .. }
         | Instruction::Arithmetic { opsize, .. } => {
             let &opsize = opsize;
             gen_profiler_stat_increment(ctx.builder, profiler::stat::CONDITION_OPTIMISED);
@@ -1834,7 +1840,7 @@ pub fn gen_getof(ctx: &mut JitContext) {
             });
             ctx.builder.and_i32();
         },
-        &Instruction::Other | Instruction::Arithmetic { .. } => {
+        Instruction::Add { .. } | Instruction::Arithmetic { .. } | Instruction::Other => {
             // TODO: add
             gen_profiler_stat_increment(ctx.builder, profiler::stat::CONDITION_UNOPTIMISED);
             gen_get_flags_changed(ctx.builder);
diff --git a/src/rust/jit.rs b/src/rust/jit.rs
index a7ec551b..8e4a8b7e 100644
--- a/src/rust/jit.rs
+++ b/src/rust/jit.rs
@@ -271,6 +271,11 @@ pub enum Instruction {
         source: InstructionOperand,
         opsize: i32,
     },
+    Add {
+        dest: InstructionOperandDest,
+        source: InstructionOperand,
+        opsize: i32,
+    },
     // Any instruction that sets last_result
     Arithmetic {
         dest: InstructionOperandDest,
diff --git a/src/rust/jit_instructions.rs b/src/rust/jit_instructions.rs
index 4663a2e4..d179f48b 100644
--- a/src/rust/jit_instructions.rs
+++ b/src/rust/jit_instructions.rs
@@ -954,9 +954,15 @@ macro_rules! define_instruction_read_write_mem32(
 );
 
 fn gen_add8(ctx: &mut JitContext, dest_operand: &WasmLocal, source_operand: &LocalOrImmediate) {
-    ctx.current_instruction = Instruction::Arithmetic {
+    ctx.current_instruction = Instruction::Add {
         opsize: OPSIZE_8,
         dest: local_to_instruction_operand(ctx, dest_operand),
+        source: if source_operand.eq_local(dest_operand) {
+            InstructionOperand::Other // aliasing
+        }
+        else {
+            source_operand.to_instruction_operand(ctx)
+        },
     };
 
     ctx.builder.const_i32(global_pointers::last_op1 as i32);
@@ -979,9 +985,15 @@ fn gen_add8(ctx: &mut JitContext, dest_operand: &WasmLocal, source_operand: &Loc
         .load_fixed_u8(global_pointers::last_result as u32);
 }
 fn gen_add32(ctx: &mut JitContext, dest_operand: &WasmLocal, source_operand: &LocalOrImmediate) {
-    ctx.current_instruction = Instruction::Arithmetic {
+    ctx.current_instruction = Instruction::Add {
         opsize: OPSIZE_32,
         dest: local_to_instruction_operand(ctx, dest_operand),
+        source: if source_operand.eq_local(dest_operand) {
+            InstructionOperand::Other // aliasing
+        }
+        else {
+            source_operand.to_instruction_operand(ctx)
+        },
     };
 
     codegen::gen_set_last_op1(ctx.builder, &dest_operand);