s390: fix 390x debug build break

R=joransiu@ca.ibm.com

Change-Id: I066b6d14694393cae43285a71bfc6aff91418505
Reviewed-on: https://chromium-review.googlesource.com/984593Reviewed-by: Joran Siu <joransiu@ca.ibm.com>
Commit-Queue: Junliang Yan <jyan@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#52287}

src/compiler/s390/instruction-selector-s390.cc

@@ -271,7 +271,7 @@ bool S390OpcodeOnlySupport12BitDisp(InstructionCode op) {
 
 ArchOpcode SelectLoadOpcode(Node* node) {
   NodeMatcher m(node);
-  DCHECK(m.IsLoad());
+  DCHECK(m.IsLoad() || m.IsPoisonedLoad());
   LoadRepresentation load_rep = LoadRepresentationOf(node->op());
   ArchOpcode opcode = kArchNop;
   switch (load_rep.representation()) {

src/s390/assembler-s390.cc

@@ -371,6 +371,7 @@ void Assembler::GetCode(Isolate* isolate, CodeDesc* desc) {
   desc->buffer_size = buffer_size_;
   desc->instr_size = pc_offset();
   desc->reloc_size = (buffer_ + buffer_size_) - reloc_info_writer.pos();
+  desc->constant_pool_size = 0;
   desc->origin = this;
   desc->unwinding_info_size = 0;
   desc->unwinding_info = nullptr;

src/s390/macro-assembler-s390.cc

@@ -1659,7 +1659,7 @@ void MacroAssembler::AssertConstructor(Register object, Register scratch) {
     STATIC_ASSERT(kSmiTag == 0);
     TestIfSmi(object);
     Check(ne, AbortReason::kOperandIsASmiAndNotAConstructor);
-    LoadP(scratch, FieldMemOperand(scratch, HeapObject::kMapOffset));
+    LoadP(scratch, FieldMemOperand(object, HeapObject::kMapOffset));
     tm(FieldMemOperand(scratch, Map::kBitFieldOffset),
        Operand(Map::IsConstructorBit::kMask));
     Check(ne, AbortReason::kOperandIsNotAConstructor);