Cache current thread in a reserved register and use it in LoadIsolate

runtime/vm/assembler_ia32_test.cc

Index: runtime/vm/assembler_ia32_test.cc
diff --git a/runtime/vm/assembler_ia32_test.cc b/runtime/vm/assembler_ia32_test.cc
index 2fd286621067807566aed22a0db9702740532592..b5415740eec97a438cce4ad15b6f99d63b73d0f6 100644
--- a/runtime/vm/assembler_ia32_test.cc
+++ b/runtime/vm/assembler_ia32_test.cc
@@ -3393,16 +3393,19 @@ ASSEMBLER_TEST_RUN(TestRepMovsBytes, test) {
 
 // Called from assembler_test.cc.
 ASSEMBLER_TEST_GENERATE(StoreIntoObject, assembler) {
+  __ pushl(THR);
   __ pushl(CTX);
-  __ movl(CTX, Address(ESP, 2 * kWordSize));
-  __ movl(EAX, Address(ESP, 3 * kWordSize));
-  __ movl(ECX, Address(ESP, 4 * kWordSize));
+  __ movl(CTX, Address(ESP, 3 * kWordSize));
+  __ movl(EAX, Address(ESP, 4 * kWordSize));
+  __ movl(ECX, Address(ESP, 5 * kWordSize));
+  __ movl(THR, Address(ESP, 6 * kWordSize));
   __ pushl(EAX);
   __ StoreIntoObject(ECX,
                      FieldAddress(ECX, GrowableObjectArray::data_offset()),
                      EAX);
   __ popl(EAX);
   __ popl(CTX);
+  __ popl(THR);
   __ ret();
 }