From b573d7e57bcb51e3368b2c96338ad454bf3393c8 Mon Sep 17 00:00:00 2001
From: ctw-ian <chentingwei2@huawei.com>
Date: Fri, 28 Oct 2022 09:10:55 +0000
Subject: [PATCH] Support Nullish Coalesce on es2abc

Issue:I5YDWR

Signed-off-by: ctw-ian <chentingwei2@huawei.com>
Change-Id: I9c4721ae3b5ddfb7778da12774a1d964df3a1e2c
---
 es2panda/compiler/core/pandagen.cpp           | 10 ++++++++++
 es2panda/compiler/core/pandagen.h             |  1 +
 es2panda/ir/expressions/binaryExpression.cpp  | 20 +++++++++++--------
 .../nullishCoalesce-expected.txt              |  3 +++
 .../js/binaryExpression/nullishCoalesce.js    |  9 +++++++++
 5 files changed, 35 insertions(+), 8 deletions(-)
 create mode 100644 es2panda/test/compiler/js/binaryExpression/nullishCoalesce-expected.txt
 create mode 100644 es2panda/test/compiler/js/binaryExpression/nullishCoalesce.js

diff --git a/es2panda/compiler/core/pandagen.cpp b/es2panda/compiler/core/pandagen.cpp
index 3488d439f9..ed81f39bda 100644
--- a/es2panda/compiler/core/pandagen.cpp
+++ b/es2panda/compiler/core/pandagen.cpp
@@ -1071,6 +1071,16 @@ void PandaGen::BranchIfFalse(const ir::AstNode *node, Label *target)
     sa_.Emit<Jnez>(node, target);
 }
 
+void PandaGen::BranchIfStrictNull(const ir::AstNode *node, class Label *target)
+{
+    RegScope rs(this);
+    VReg tmp = AllocReg();
+    StoreAccumulator(node, tmp);
+    LoadConst(node, Constant::JS_NULL);
+    ra_.Emit<Stricteq>(node, 0, tmp);
+    sa_.Emit<Jnez>(node, target);
+}
+
 void PandaGen::EmitThrow(const ir::AstNode *node)
 {
     sa_.Emit<Throw>(node);
diff --git a/es2panda/compiler/core/pandagen.h b/es2panda/compiler/core/pandagen.h
index cdc5a69bc9..02f17f126c 100644
--- a/es2panda/compiler/core/pandagen.h
+++ b/es2panda/compiler/core/pandagen.h
@@ -313,6 +313,7 @@ public:
     void BranchIfNotTrue(const ir::AstNode *node, class Label *target);
     void BranchIfFalse(const ir::AstNode *node, class Label *target);
     void BranchIfNotFalse(const ir::AstNode *node, class Label *target);
+    void BranchIfStrictNull(const ir::AstNode *node, class Label *target);
 
     void EmitThrow(const ir::AstNode *node);
     void EmitRethrow(const ir::AstNode *node);
diff --git a/es2panda/ir/expressions/binaryExpression.cpp b/es2panda/ir/expressions/binaryExpression.cpp
index 58fafd3d1a..526685b453 100644
--- a/es2panda/ir/expressions/binaryExpression.cpp
+++ b/es2panda/ir/expressions/binaryExpression.cpp
@@ -43,13 +43,9 @@ void BinaryExpression::CompileLogical(compiler::PandaGen *pg) const
     compiler::RegScope rs(pg);
     compiler::VReg lhs = pg->AllocReg();
 
-    if (operator_ == lexer::TokenType::PUNCTUATOR_NULLISH_COALESCING) {
-        // TODO(parser): Nullish Coalesce
-        compiler::PandaGen::Unimplemented();
-    }
-
     ASSERT(operator_ == lexer::TokenType::PUNCTUATOR_LOGICAL_AND ||
-           operator_ == lexer::TokenType::PUNCTUATOR_LOGICAL_OR);
+           operator_ == lexer::TokenType::PUNCTUATOR_LOGICAL_OR ||
+           operator_ == lexer::TokenType::PUNCTUATOR_NULLISH_COALESCING);
     auto *skipRight = pg->AllocLabel();
     auto *endLabel = pg->AllocLabel();
 
@@ -59,9 +55,17 @@ void BinaryExpression::CompileLogical(compiler::PandaGen *pg) const
 
     if (operator_ == lexer::TokenType::PUNCTUATOR_LOGICAL_AND) {
         pg->BranchIfFalse(this, skipRight);
-    } else {
-        ASSERT(operator_ == lexer::TokenType::PUNCTUATOR_LOGICAL_OR);
+    } else if (operator_ == lexer::TokenType::PUNCTUATOR_LOGICAL_OR) {
         pg->BranchIfTrue(this, skipRight);
+    } else {
+        ASSERT(operator_ == lexer::TokenType::PUNCTUATOR_NULLISH_COALESCING);
+        auto *nullish = pg->AllocLabel();
+        // if lhs === null
+        pg->BranchIfStrictNull(this, nullish);
+        pg->LoadAccumulator(this, lhs);
+        // if lhs === undefined
+        pg->BranchIfStrictNotUndefined(this, skipRight);
+        pg->SetLabel(this, nullish);
     }
 
     // left is true/false(and/or) then right -> acc
diff --git a/es2panda/test/compiler/js/binaryExpression/nullishCoalesce-expected.txt b/es2panda/test/compiler/js/binaryExpression/nullishCoalesce-expected.txt
new file mode 100644
index 0000000000..0429fae9e5
--- /dev/null
+++ b/es2panda/test/compiler/js/binaryExpression/nullishCoalesce-expected.txt
@@ -0,0 +1,3 @@
+2
+4
+5
diff --git a/es2panda/test/compiler/js/binaryExpression/nullishCoalesce.js b/es2panda/test/compiler/js/binaryExpression/nullishCoalesce.js
new file mode 100644
index 0000000000..45d895e52b
--- /dev/null
+++ b/es2panda/test/compiler/js/binaryExpression/nullishCoalesce.js
@@ -0,0 +1,9 @@
+let a = 2;
+let b = a ?? 3;
+print(b);
+a = null;
+b = a ?? 4;
+print(b);
+a = undefined;
+b = a ?? 5;
+print(b);
\ No newline at end of file
-- 
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