We have to be sure to generate a relocatable instruction when

handling external references before a heap serialization.
Review URL: http://codereview.chromium.org/151080

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2310 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/assembler-arm.cc

@@ -491,6 +491,20 @@ static bool fits_shifter(uint32_t imm32,
 }
 
 
+// We have to use the temporary register for things that can be relocated even
+// if they can be encoded in the ARM's 12 bits of immediate-offset instruction
+// space.  There is no guarantee that the relocated location can be similarly
+// encoded.
+static bool MustUseIp(RelocInfo::Mode rmode) {
+  if (rmode == RelocInfo::EXTERNAL_REFERENCE) {
+    return Serializer::enabled();
+  } else if (rmode == RelocInfo::NONE) {
+    return false;
+  }
+  return true;
+}
+
+
 void Assembler::addrmod1(Instr instr,
                          Register rn,
                          Register rd,
@@ -501,8 +515,7 @@ void Assembler::addrmod1(Instr instr,
     // immediate
     uint32_t rotate_imm;
     uint32_t immed_8;
-    if ((x.rmode_ != RelocInfo::NONE &&
-         x.rmode_ != RelocInfo::EXTERNAL_REFERENCE) ||
+    if (MustUseIp(x.rmode_) ||
         !fits_shifter(x.imm32_, &rotate_imm, &immed_8, &instr)) {
       // The immediate operand cannot be encoded as a shifter operand, so load
       // it first to register ip and change the original instruction to use ip.
@@ -904,8 +917,7 @@ void Assembler::msr(SRegisterFieldMask fields, const Operand& src,
     // immediate
     uint32_t rotate_imm;
     uint32_t immed_8;
-    if ((src.rmode_ != RelocInfo::NONE &&
-         src.rmode_ != RelocInfo::EXTERNAL_REFERENCE)||
+    if (MustUseIp(src.rmode_) ||
         !fits_shifter(src.imm32_, &rotate_imm, &immed_8, NULL)) {
       // immediate operand cannot be encoded, load it first to register ip
       RecordRelocInfo(src.rmode_, src.imm32_);