ARM/ARM64: Fix smashed CODE_REG in intrinsics with InvokeMathCFunctionInstrs.

runtime/vm/intrinsifier_ia32.cc

Index: runtime/vm/intrinsifier_ia32.cc
diff --git a/runtime/vm/intrinsifier_ia32.cc b/runtime/vm/intrinsifier_ia32.cc
index 576c6a06acf43991a39d57c2aba52aeedc5a35d2..130b5d69e9e2c3441c25e8adae9c51e9ac07131c 100644
--- a/runtime/vm/intrinsifier_ia32.cc
+++ b/runtime/vm/intrinsifier_ia32.cc
@@ -41,16 +41,16 @@ intptr_t Intrinsifier::ParameterSlotFromSp() { return 0; }
 
 
 void Intrinsifier::IntrinsicCallPrologue(Assembler* assembler) {
+  COMPILE_ASSERT(CALLEE_SAVED_TEMP != ARGS_DESC_REG);
+
   assembler->Comment("IntrinsicCallPrologue");
-  assembler->movl(CALLEE_SAVED_TEMP, ICREG);

[Vyacheslav Egorov (Google), 2016/05/25 11:15:31]

I wonder why this was preserved in the first place. I can't find any uses in the
prologue.

[rmacnak, 2016/05/25 16:58:51]

I suspect it was for something in the past. I previously removed it from
ParallelMoveResolver when adding support for the iOS ARM ABI.

-  assembler->movl(CALLEE_SAVED_TEMP2, ARGS_DESC_REG);
+  assembler->movl(CALLEE_SAVED_TEMP, ARGS_DESC_REG);
 }
 
 
 void Intrinsifier::IntrinsicCallEpilogue(Assembler* assembler) {
   assembler->Comment("IntrinsicCallEpilogue");
-  assembler->movl(ICREG, CALLEE_SAVED_TEMP);
-  assembler->movl(ARGS_DESC_REG, CALLEE_SAVED_TEMP2);
+  assembler->movl(ARGS_DESC_REG, CALLEE_SAVED_TEMP);
 }