From fd7c7b7c574f2df17818016f58d6eef6deb07f79 Mon Sep 17 00:00:00 2001
From: Cameron Clark <cameron.clark@hey.com>
Date: Tue, 31 Dec 2024 02:16:25 +0000
Subject: [PATCH] feat(minifier): try collapse conditional to logical or expr

---
 .../peephole_minimize_conditions.rs           | 40 ++++++++++++++-----
 tasks/minsize/minsize.snap                    |  4 +-
 2 files changed, 33 insertions(+), 11 deletions(-)

diff --git a/crates/oxc_minifier/src/ast_passes/peephole_minimize_conditions.rs b/crates/oxc_minifier/src/ast_passes/peephole_minimize_conditions.rs
index f3b4e8593bd3a..088de64dddbbf 100644
--- a/crates/oxc_minifier/src/ast_passes/peephole_minimize_conditions.rs
+++ b/crates/oxc_minifier/src/ast_passes/peephole_minimize_conditions.rs
@@ -57,6 +57,9 @@ impl<'a> Traverse<'a> for PeepholeMinimizeConditions {
     fn exit_expression(&mut self, expr: &mut Expression<'a>, ctx: &mut TraverseCtx<'a>) {
         if let Some(folded_expr) = match expr {
             Expression::UnaryExpression(e) => Self::try_minimize_not(e, ctx),
+            Expression::ConditionalExpression(conditional_expr) => {
+                Self::try_minimize_conditional(conditional_expr, ctx)
+            }
             _ => None,
         } {
             *expr = folded_expr;
@@ -253,6 +256,28 @@ impl<'a> PeepholeMinimizeConditions {
             None => ctx.ast.void_0(return_stmt.span),
         }
     }
+
+    /// `a ? a : b` -> `a || b`
+    fn try_minimize_conditional(
+        expr: &mut ConditionalExpression<'a>,
+        ctx: &mut TraverseCtx<'a>,
+    ) -> Option<Expression<'a>> {
+        let Expression::Identifier(test_ident) = &expr.test else { return None };
+        let Expression::Identifier(consequent_ident) = &expr.consequent else { return None };
+
+        if test_ident.name != consequent_ident.name {
+            return None;
+        }
+
+        let ident = ctx.ast.move_expression(&mut expr.test);
+
+        Some(ctx.ast.expression_logical(
+            expr.span,
+            ident,
+            LogicalOperator::Or,
+            ctx.ast.move_expression(&mut expr.alternate),
+        ))
+    }
 }
 
 /// <https://github.com/google/closure-compiler/blob/v20240609/test/com/google/javascript/jscomp/PeepholeMinimizeConditionsTest.java>
@@ -662,21 +687,18 @@ mod test {
     }
 
     #[test]
-    #[ignore]
     fn test_minimize_hook() {
         fold("x ? x : y", "x || y");
-        // We assume GETPROPs don't have side effects.
-        fold("x.y ? x.y : x.z", "x.y || x.z");
-        fold("x?.y ? x?.y : x.z", "x?.y || x.z");
-        fold("x?.y ? x?.y : x?.z", "x?.y || x?.z");
+        fold_same("x.y ? x.y : x.z");
+        fold_same("x?.y ? x?.y : x.z");
+        fold_same("x?.y ? x?.y : x?.z");
 
-        // This can be folded if x() does not have side effects.
         fold_same("x() ? x() : y()");
         fold_same("x?.() ? x?.() : y()");
 
-        fold("!x ? foo() : bar()", "x ? bar() : foo()");
-        fold("while(!(x ? y : z)) foo();", "while(x ? !y : !z) foo();");
-        fold("(x ? !y : !z) ? foo() : bar()", "(x ? y : z) ? bar() : foo()");
+        // fold("!x ? foo() : bar()", "x ? bar() : foo()");
+        // fold("while(!(x ? y : z)) foo();", "while(x ? !y : !z) foo();");
+        // fold("(x ? !y : !z) ? foo() : bar()", "(x ? y : z) ? bar() : foo()");
     }
 
     #[test]
diff --git a/tasks/minsize/minsize.snap b/tasks/minsize/minsize.snap
index 93dc7f191d799..934fbc3765a1a 100644
--- a/tasks/minsize/minsize.snap
+++ b/tasks/minsize/minsize.snap
@@ -21,7 +21,7 @@ Original   | minified   | minified   | gzip       | gzip       | Fixture
 
 3.20 MB    | 1.01 MB    | 1.01 MB    | 332.21 kB  | 331.56 kB  | echarts.js
 
-6.69 MB    | 2.32 MB    | 2.31 MB    | 493.08 kB  | 488.28 kB  | antd.js   
+6.69 MB    | 2.32 MB    | 2.31 MB    | 493.07 kB  | 488.28 kB  | antd.js   
 
-10.95 MB   | 3.51 MB    | 3.49 MB    | 910.42 kB  | 915.50 kB  | typescript.js
+10.95 MB   | 3.51 MB    | 3.49 MB    | 910.37 kB  | 915.50 kB  | typescript.js