From 2fb7d3d583d15cea366881bb3bd13d6604115ec5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dominik=20Inf=C3=BChr?= <dominik.infuehr@gmail.com>
Date: Sun, 27 Oct 2024 22:14:07 +0100
Subject: [PATCH] boots: Start removing duplicate stores as well

---
 pkgs/boots/load_elimination.dora | 13 +++++++++++++
 tests/opt/load-elimination.dora  | 11 +++++++++++
 2 files changed, 24 insertions(+)

diff --git a/pkgs/boots/load_elimination.dora b/pkgs/boots/load_elimination.dora
index 17a225ef0..73374b5de 100644
--- a/pkgs/boots/load_elimination.dora
+++ b/pkgs/boots/load_elimination.dora
@@ -64,9 +64,22 @@ pub fn performLoadElimination(ci: CompilationInfo, graph: Graph) {
                 if inst.hasClassInfo() {
                     let class_info = inst.getClassInfo();
                     let field_offset = inst.getOffset();
+
+                    let object = inst.getInput(0).getValue();
+                    let field = Field(object, class_info, field_offset);
+                    let cur_value = data.class_values.get(field);
+
                     data.class_values.retainIf(|field: Field, value: Inst|: Bool {
                         field.class_info != class_info || field.offset != field_offset
                     });
+
+                    let new_value = inst.getInput(1).getValue();
+                    if cur_value is Some(cur_value) && cur_value == new_value {
+                        assert(!inst.hasUses());
+                        inst.remove();
+                    }
+
+                    data.class_values.insert(field, new_value);
                 }
 
             } else if op.isCall() {
diff --git a/tests/opt/load-elimination.dora b/tests/opt/load-elimination.dora
index 673dace76..01a3d74ba 100644
--- a/tests/opt/load-elimination.dora
+++ b/tests/opt/load-elimination.dora
@@ -14,6 +14,9 @@ fn main() {
 
     let x = Foo(100, 300);
     assert(f3(x, x) == 200);
+
+    let x = Foo(100, 300);
+    assert(f4(x, 12) == 12);
 }
 
 @Optimize
@@ -34,3 +37,11 @@ fn f3(foo: Foo, foo2: Foo): Int {
     foo2.b = 10;
     x + foo.a
 }
+
+@Optimize
+fn f4(foo: Foo, value: Int): Int {
+    let tmp = foo.a;
+    foo.a = value;
+    foo.a = value;
+    foo.a
+}