Fix inlined keyed property load on ARM...

src/arm/codegen-arm.cc

Index: src/arm/codegen-arm.cc
===================================================================
--- src/arm/codegen-arm.cc	(revision 4624)
+++ src/arm/codegen-arm.cc	(working copy)
@@ -5578,8 +5578,8 @@
 
     // Load the key and receiver from the stack to r0 and r1.
     frame_->PopToR1R0();
-    Register receiver = r0;
-    Register key = r1;
+    Register key = r0;
+    Register receiver = r1;
     VirtualFrame::SpilledScope spilled(frame_);
 
     // The deferred code expects key and receiver in r0 and r1.
@@ -5595,7 +5595,7 @@
     // instructions generated need to be fixed, so the constant pool is blocked
     // while generating this code.
 #ifdef DEBUG
-    int kInlinedKeyedLoadInstructions = 19;
+    int kInlinedKeyedLoadInstructions = 20;
     Label check_inlined_codesize;
     masm_->bind(&check_inlined_codesize);
 #endif
@@ -5632,15 +5632,13 @@
       __ add(scratch1,
              scratch1,
              Operand(FixedArray::kHeaderSize - kHeapObjectTag));
-      __ ldr(r0,
+      __ ldr(ip,

[Erik Corry, 2010/05/10 10:16:48]

Ip is a register that is used behind our backs by the macro assembler.  We are a
little lax about not making the assumption that we can use it for other things. 
In this case we are expecting it to be preserved across four instructions, one
of which is not even generated here (it's in the deferred object's Branch
method).  I would feel better if we used VirtualFrame::scratch0() for this.

[Søren Thygesen Gjesse, 2010/05/10 10:45:26]

Done.

              MemOperand(scratch1, key, LSL,
                         kPointerSizeLog2 - (kSmiTagSize + kSmiShiftSize)));
-      __ cmp(r0, scratch2);
-      // This is the only branch to deferred where r0 and r1 do not contain the
-      // receiver and key.  We can't just load undefined here because we have to
-      // check the prototype.
+      __ cmp(ip, scratch2);
       deferred->Branch(eq);
 
+      __ mov(r0, ip);
       // Make sure that the expected number of instructions are generated.
       ASSERT_EQ(kInlinedKeyedLoadInstructions,
                 masm_->InstructionsGeneratedSince(&check_inlined_codesize));