From 0ea7c7cd81880bfe855a59c60d45c978b83b3a15 Mon Sep 17 00:00:00 2001
From: Fabian <copy@copy.sh>
Date: Fri, 4 Nov 2022 12:30:33 -0600
Subject: [PATCH] optimise getof

---
 src/rust/codegen.rs | 102 ++++++++++++++++++++++++++++----------------
 1 file changed, 66 insertions(+), 36 deletions(-)

diff --git a/src/rust/codegen.rs b/src/rust/codegen.rs
index d1ec3066..043274e1 100644
--- a/src/rust/codegen.rs
+++ b/src/rust/codegen.rs
@@ -1784,48 +1784,78 @@ pub fn gen_getsf(ctx: &mut JitContext) {
 }
 
 pub fn gen_getof(ctx: &mut JitContext) {
-    gen_profiler_stat_increment(ctx.builder, profiler::stat::CONDITION_UNOPTIMISED);
-    gen_get_flags_changed(ctx.builder);
-    let flags_changed = ctx.builder.tee_new_local();
-    ctx.builder.const_i32(FLAG_OVERFLOW);
-    ctx.builder.and_i32();
-    ctx.builder.if_i32();
-    {
-        gen_get_last_op1(ctx.builder, &ctx.previous_instruction);
-        let last_op1 = ctx.builder.tee_new_local();
-        gen_get_last_result(ctx.builder, &ctx.previous_instruction);
-        let last_result = ctx.builder.tee_new_local();
-        ctx.builder.xor_i32();
+    match &ctx.previous_instruction {
+        Instruction::Cmp { opsize, .. } | Instruction::Sub { opsize, .. } => {
+            let &opsize = opsize;
+            gen_profiler_stat_increment(ctx.builder, profiler::stat::CONDITION_OPTIMISED);
+            gen_get_last_op1(ctx.builder, &ctx.previous_instruction);
+            gen_get_last_result(ctx.builder, &ctx.previous_instruction);
+            ctx.builder.xor_i32();
 
-        ctx.builder.get_local(&last_result);
-        ctx.builder.get_local(&last_op1);
-        ctx.builder.sub_i32();
-        gen_get_flags_changed(ctx.builder);
-        ctx.builder.const_i32(31);
-        ctx.builder.shr_u_i32();
-        ctx.builder.sub_i32();
+            gen_get_last_op1(ctx.builder, &ctx.previous_instruction);
+            gen_get_last_op1(ctx.builder, &ctx.previous_instruction);
+            gen_get_last_result(ctx.builder, &ctx.previous_instruction);
+            ctx.builder.sub_i32();
+            ctx.builder.xor_i32();
+            ctx.builder.and_i32();
 
-        ctx.builder.get_local(&last_result);
-        ctx.builder.xor_i32();
+            ctx.builder.const_i32(if opsize == OPSIZE_32 {
+                0x8000_0000u32 as i32
+            }
+            else if opsize == OPSIZE_16 {
+                0x8000
+            }
+            else {
+                0x80
+            });
+            ctx.builder.and_i32();
+        },
+        &Instruction::Other | Instruction::Arithmetic { .. } => {
+            // TODO: add
+            gen_profiler_stat_increment(ctx.builder, profiler::stat::CONDITION_UNOPTIMISED);
+            gen_get_flags_changed(ctx.builder);
+            let flags_changed = ctx.builder.tee_new_local();
+            ctx.builder.const_i32(FLAG_OVERFLOW);
+            ctx.builder.and_i32();
+            ctx.builder.if_i32();
+            {
+                gen_get_last_op1(ctx.builder, &ctx.previous_instruction);
+                let last_op1 = ctx.builder.tee_new_local();
+                gen_get_last_result(ctx.builder, &ctx.previous_instruction);
+                let last_result = ctx.builder.tee_new_local();
+                ctx.builder.xor_i32();
 
-        ctx.builder.and_i32();
+                ctx.builder.get_local(&last_result);
+                ctx.builder.get_local(&last_op1);
+                ctx.builder.sub_i32();
+                gen_get_flags_changed(ctx.builder);
+                ctx.builder.const_i32(31);
+                ctx.builder.shr_u_i32();
+                ctx.builder.sub_i32();
 
-        gen_get_last_op_size(ctx.builder);
-        ctx.builder.shr_u_i32();
-        ctx.builder.const_i32(1);
-        ctx.builder.and_i32();
+                ctx.builder.get_local(&last_result);
+                ctx.builder.xor_i32();
 
-        ctx.builder.free_local(last_op1);
-        ctx.builder.free_local(last_result);
+                ctx.builder.and_i32();
+
+                gen_get_last_op_size(ctx.builder);
+                ctx.builder.shr_u_i32();
+                ctx.builder.const_i32(1);
+                ctx.builder.and_i32();
+
+                ctx.builder.free_local(last_op1);
+                ctx.builder.free_local(last_result);
+            }
+            ctx.builder.else_();
+            {
+                gen_get_flags(ctx.builder);
+                ctx.builder.const_i32(FLAG_OVERFLOW);
+                ctx.builder.and_i32();
+            }
+            ctx.builder.block_end();
+            ctx.builder.free_local(flags_changed);
+        },
     }
-    ctx.builder.else_();
-    {
-        gen_get_flags(ctx.builder);
-        ctx.builder.const_i32(FLAG_OVERFLOW);
-        ctx.builder.and_i32();
-    }
-    ctx.builder.block_end();
-    ctx.builder.free_local(flags_changed);
 }
 
 pub fn gen_test_be(ctx: &mut JitContext, negate: ConditionNegate) {