Expand TCO on nullish and conditional expression

Signed-off-by: HyukWoo Park <[email protected]>
Samsung · May 11, 2023 · 0285779 · 0285779
1 parent f621248
commit 0285779
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Showing 6 changed files with 57 additions and 21 deletions.
diff --git a/src/parser/ast/BinaryExpressionNullishCoalescingNode.h b/src/parser/ast/BinaryExpressionNullishCoalescingNode.h
@@ -42,19 +42,38 @@ class BinaryExpressionNullishCoalescingNode : public ExpressionNode {
             context->m_canSkipCopyToRegister = false;
         }
 
-        size_t resultRegisterExpected = dstRegister;
+        m_left->generateExpressionByteCode(codeBlock, context, dstRegister);
 
-        m_left->generateExpressionByteCode(codeBlock, context, resultRegisterExpected);
-
-        codeBlock->pushCode<JumpIfUndefinedOrNull>(JumpIfUndefinedOrNull(ByteCodeLOC(m_loc.index), true, resultRegisterExpected), context, this->m_loc.index);
+        codeBlock->pushCode<JumpIfUndefinedOrNull>(JumpIfUndefinedOrNull(ByteCodeLOC(m_loc.index), true, dstRegister), context, this->m_loc.index);
         size_t pos = codeBlock->lastCodePosition<JumpIfUndefinedOrNull>();
 
-        m_right->generateExpressionByteCode(codeBlock, context, resultRegisterExpected);
+        m_right->generateExpressionByteCode(codeBlock, context, dstRegister);
+        codeBlock->peekCode<JumpIfUndefinedOrNull>(pos)->m_jumpPosition = codeBlock->currentCodeSize();
+
+        context->m_canSkipCopyToRegister = directBefore;
+    }
+
+#if defined(ENABLE_TCO)
+    virtual void generateTCOExpressionByteCode(ByteCodeBlock* codeBlock, ByteCodeGenerateContext* context, ByteCodeRegisterIndex dstRegister, bool& isTailCall) override
+    {
+        bool isSlow = !canUseDirectRegister(context, m_left, m_right);
+        bool directBefore = context->m_canSkipCopyToRegister;
+        if (isSlow) {
+            context->m_canSkipCopyToRegister = false;
+        }
+
+        m_left->generateExpressionByteCode(codeBlock, context, dstRegister);
+
+        codeBlock->pushCode<JumpIfUndefinedOrNull>(JumpIfUndefinedOrNull(ByteCodeLOC(m_loc.index), true, dstRegister), context, this->m_loc.index);
+        size_t pos = codeBlock->lastCodePosition<JumpIfUndefinedOrNull>();
 
+        // try TCO only for right hand-side because we need to check the result of left hand-side expression
+        m_right->generateTCOExpressionByteCode(codeBlock, context, dstRegister, isTailCall);
         codeBlock->peekCode<JumpIfUndefinedOrNull>(pos)->m_jumpPosition = codeBlock->currentCodeSize();
 
         context->m_canSkipCopyToRegister = directBefore;
     }
+#endif
 
     virtual void iterateChildrenIdentifier(const std::function<void(AtomicString name, bool isAssignment)>& fn) override
     {

diff --git a/src/parser/ast/CallExpressionNode.h b/src/parser/ast/CallExpressionNode.h
@@ -288,7 +288,7 @@ class CallExpressionNode : public ExpressionNode {
     }
 
 #if defined(ENABLE_TCO)
-    virtual void generateTCOExpressionByteCode(ByteCodeBlock* codeBlock, ByteCodeGenerateContext* context, ByteCodeRegisterIndex dstRegister, bool& skipEnd) override
+    virtual void generateTCOExpressionByteCode(ByteCodeBlock* codeBlock, ByteCodeGenerateContext* context, ByteCodeRegisterIndex dstRegister, bool& isTailCall) override
     {
         if (m_callee->isIdentifier() && m_callee->asIdentifier()->name().string()->equals("eval")) {
             ByteCodeRegisterIndex evalIndex = context->getRegister();
@@ -416,8 +416,7 @@ class CallExpressionNode : public ExpressionNode {
         } else if (isCalleeHasReceiver) {
             if (dstRegister == context->m_returnRegister) {
                 // Try tail recursion optimization (TCO)
-                ASSERT(!skipEnd);
-                skipEnd = true;
+                isTailCall = true;
                 if (context->m_codeBlock->isTailRecursionTarget()) {
                     codeBlock->pushCode(TailRecursionWithReceiver(ByteCodeLOC(m_loc.index), receiverIndex, calleeIndex, argumentsStartIndex, m_arguments.size()), context, this->m_loc.index);
                 } else {
@@ -429,8 +428,7 @@ class CallExpressionNode : public ExpressionNode {
         } else {
             if (dstRegister == context->m_returnRegister) {
                 // Try tail recursion optimization (TCO)
-                ASSERT(!skipEnd);
-                skipEnd = true;
+                isTailCall = true;
                 if (context->m_codeBlock->isTailRecursionTarget()) {
                     codeBlock->pushCode(TailRecursion(ByteCodeLOC(m_loc.index), calleeIndex, argumentsStartIndex, m_arguments.size()), context, this->m_loc.index);
                 } else {

diff --git a/src/parser/ast/ConditionalExpressionNode.h b/src/parser/ast/ConditionalExpressionNode.h
@@ -37,8 +37,6 @@ class ConditionalExpressionNode : public ExpressionNode {
     virtual ASTNodeType type() override { return ASTNodeType::ConditionalExpression; }
     virtual void generateExpressionByteCode(ByteCodeBlock* codeBlock, ByteCodeGenerateContext* context, ByteCodeRegisterIndex dstRegister) override
     {
-        size_t resultRegisterExpected = dstRegister;
-
         size_t testReg = m_test->getRegister(codeBlock, context);
         m_test->generateExpressionByteCode(codeBlock, context, testReg);
         codeBlock->pushCode(JumpIfFalse(ByteCodeLOC(m_loc.index), testReg), context, this->m_loc.index);
@@ -59,6 +57,30 @@ class ConditionalExpressionNode : public ExpressionNode {
         jumpForEndOfConsequence->m_jumpPosition = codeBlock->currentCodeSize();
     }
 
+#if defined(ENABLE_TCO)
+    virtual void generateTCOExpressionByteCode(ByteCodeBlock* codeBlock, ByteCodeGenerateContext* context, ByteCodeRegisterIndex dstRegister, bool& isTailCall) override
+    {
+        size_t testReg = m_test->getRegister(codeBlock, context);
+        m_test->generateExpressionByteCode(codeBlock, context, testReg);
+        codeBlock->pushCode(JumpIfFalse(ByteCodeLOC(m_loc.index), testReg), context, this->m_loc.index);
+
+        // give testReg
+        context->giveUpRegister();
+
+        size_t jumpPosForTestIsFalse = codeBlock->lastCodePosition<JumpIfFalse>();
+        m_consequente->generateTCOExpressionByteCode(codeBlock, context, dstRegister, isTailCall);
+        codeBlock->pushCode(Jump(ByteCodeLOC(m_loc.index), SIZE_MAX), context, this->m_loc.index);
+        JumpIfFalse* jumpForTestIsFalse = codeBlock->peekCode<JumpIfFalse>(jumpPosForTestIsFalse);
+        size_t jumpPosForEndOfConsequence = codeBlock->lastCodePosition<Jump>();
+
+        jumpForTestIsFalse->m_jumpPosition = codeBlock->currentCodeSize();
+        m_alternate->generateTCOExpressionByteCode(codeBlock, context, dstRegister, isTailCall);
+
+        Jump* jumpForEndOfConsequence = codeBlock->peekCode<Jump>(jumpPosForEndOfConsequence);
+        jumpForEndOfConsequence->m_jumpPosition = codeBlock->currentCodeSize();
+    }
+#endif
+
     virtual void iterateChildrenIdentifier(const std::function<void(AtomicString name, bool isAssignment)>& fn) override
     {
         m_test->iterateChildrenIdentifier(fn);

diff --git a/src/parser/ast/Node.h b/src/parser/ast/Node.h
@@ -316,9 +316,9 @@ class Node {
     }
 
 #if defined(ENABLE_TCO)
-    virtual void generateTCOExpressionByteCode(ByteCodeBlock* codeBlock, ByteCodeGenerateContext* context, ByteCodeRegisterIndex dstRegister, bool& skipEnd)
+    virtual void generateTCOExpressionByteCode(ByteCodeBlock* codeBlock, ByteCodeGenerateContext* context, ByteCodeRegisterIndex dstRegister, bool& isTailCall)
     {
-        UNUSED_PARAMETER(skipEnd);
+        UNUSED_PARAMETER(isTailCall);
         generateExpressionByteCode(codeBlock, context, dstRegister);
     }
 #endif

diff --git a/src/parser/ast/ReturnStatementNode.h b/src/parser/ast/ReturnStatementNode.h
@@ -60,15 +60,15 @@ class ReturnStatementNode : public StatementNode {
             }
             context->giveUpRegister();
         } else {
-            bool skipEnd = false;
+            bool isTailCall = false;
             size_t r;
             if (m_argument) {
                 r = m_argument->getRegister(codeBlock, context);
                 if (context->tryCatchWithBlockStatementCount() == 0) {
                     // consider tail recursion (TCO)
                     context->setReturnRegister(r);
 #if defined(ENABLE_TCO)
-                    m_argument->generateTCOExpressionByteCode(codeBlock, context, r, skipEnd);
+                    m_argument->generateTCOExpressionByteCode(codeBlock, context, r, isTailCall);
 #else
                     m_argument->generateExpressionByteCode(codeBlock, context, r);
 #endif
@@ -81,7 +81,8 @@ class ReturnStatementNode : public StatementNode {
                 codeBlock->pushCode(LoadLiteral(ByteCodeLOC(m_loc.index), r, Value()), context, this->m_loc.index);
             }
 
-            if (!skipEnd) {
+            if (!isTailCall || (m_argument->type() != CallExpression)) {
+                // skip End bytecode only if it directly returns the result of tail call
                 codeBlock->pushCode(End(ByteCodeLOC(m_loc.index), r), context, this->m_loc.index);
             }
             context->giveUpRegister();

diff --git a/tools/test/test262/excludelist.orig.xml b/tools/test/test262/excludelist.orig.xml
@@ -5070,8 +5070,6 @@
     <test id="language/expressions/class/scope-name-lex-open-heritage"><reason>TODO</reason></test>
     <test id="language/expressions/coalesce/chainable-if-parenthesis-covered-logical-and"><reason>TODO</reason></test>
     <test id="language/expressions/coalesce/chainable-if-parenthesis-covered-logical-or"><reason>TODO</reason></test>
-    <test id="language/expressions/coalesce/tco-pos-null"><reason>TODO</reason></test>
-    <test id="language/expressions/coalesce/tco-pos-undefined"><reason>TODO</reason></test>
     <test id="language/expressions/comma/tco-final"><reason>TODO</reason></test>
     <test id="language/expressions/compound-assignment/S11.13.2_A6.10_T1"><reason>TODO</reason></test>
     <test id="language/expressions/compound-assignment/S11.13.2_A6.11_T1"><reason>TODO</reason></test>
@@ -5117,8 +5115,6 @@
     <test id="language/expressions/compound-assignment/right-shift-non-simple"><reason>TODO</reason></test>
     <test id="language/expressions/compound-assignment/subtract-non-simple"><reason>TODO</reason></test>
     <test id="language/expressions/compound-assignment/u-right-shift-non-simple"><reason>TODO</reason></test>
-    <test id="language/expressions/conditional/tco-cond"><reason>TODO</reason></test>
-    <test id="language/expressions/conditional/tco-pos"><reason>TODO</reason></test>
     <test id="language/expressions/delete/super-property-null-base"><reason>TODO</reason></test>
     <test id="language/expressions/dynamic-import/2nd-param-assert-enumeration"><reason>TODO</reason></test>
     <test id="language/expressions/function/eval-var-scope-syntax-err"><reason>TODO</reason></test>