Bug 1204028: Evaluate LHS reference before RHS in destructuring

Issue #73
[Depends on] Bug 1147371: Implement IteratorClose

1 files changed, 29 insertions, 1 deletions

diff --git a/js/src/jit/BaselineCompiler.cpp b/js/src/jit/BaselineCompiler.cpp
index 4dcc10b61..2f0d41707 100644
--- a/js/src/jit/BaselineCompiler.cpp
+++ b/js/src/jit/BaselineCompiler.cpp
@@ -1147,7 +1147,7 @@ BaselineCompiler::emit_JSOP_PICK()
     //     after : A B D E C
 
     // First, move value at -(amount + 1) into R0.
-    int depth = -(GET_INT8(pc) + 1);
+    int32_t depth = -(GET_INT8(pc) + 1);
     masm.loadValue(frame.addressOfStackValue(frame.peek(depth)), R0);
 
     // Move the other values down.
@@ -1166,6 +1166,34 @@ BaselineCompiler::emit_JSOP_PICK()
 }
 
 bool
+BaselineCompiler::emit_JSOP_UNPICK()
+{
+    frame.syncStack(0);
+
+    // Pick takes the top of the stack value and moves it under the nth value.
+    // For instance, unpick 2:
+    //     before: A B C D E
+    //     after : A B E C D
+
+    // First, move value at -1 into R0.
+    masm.loadValue(frame.addressOfStackValue(frame.peek(-1)), R0);
+
+    // Move the other values up.
+    int32_t depth = -(GET_INT8(pc) + 1);
+    for (int32_t i = -1; i > depth; i--) {
+        Address source = frame.addressOfStackValue(frame.peek(i - 1));
+        Address dest = frame.addressOfStackValue(frame.peek(i));
+        masm.loadValue(source, R1);
+        masm.storeValue(R1, dest);
+    }
+
+    // Store R0 under the nth value.
+    Address dest = frame.addressOfStackValue(frame.peek(depth));
+    masm.storeValue(R0, dest);
+    return true;
+}
+
+bool
 BaselineCompiler::emit_JSOP_GOTO()
 {
     frame.syncStack(0);