PPC: fix DCHECK errors

R=joransiu@ca.ibm.com

Change-Id: I8294e4719b134920cc93ad2f9f3be0a513dee0c3
Reviewed-on: https://chromium-review.googlesource.com/1222649Reviewed-by: Joran Siu <joransiu@ca.ibm.com>
Commit-Queue: Junliang Yan <jyan@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#55841}

src/compiler/ppc/code-generator-ppc.cc

@@ -2070,7 +2070,7 @@ CodeGenerator::CodeGenResult CodeGenerator::AssembleArchInstruction(
       Register output = i.OutputRegister();
       Register temp1 = r0;
       Register temp2 = kScratchReg;
-      Register temp3 = i.InputRegister(1);
+      Register temp3 = i.TempRegister(0);
       __ rldicl(temp1, input, 32, 32);
       __ rotlwi(temp2, input, 8);
       __ rlwimi(temp2, input, 24, 0, 7);

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

@@ -939,8 +939,9 @@ void InstructionSelector::VisitWord64ReverseBits(Node* node) { UNREACHABLE(); }
 
 void InstructionSelector::VisitWord64ReverseBytes(Node* node) {
   PPCOperandGenerator g(this);
+  InstructionOperand temp[] = {g.TempRegister()};
   Emit(kPPC_ByteRev64, g.DefineAsRegister(node),
-       g.UseRegister(node->InputAt(0)), g.TempRegister());
+       g.UseRegister(node->InputAt(0)), 1, temp);
 }
 
 void InstructionSelector::VisitWord32ReverseBytes(Node* node) {

src/ppc/macro-assembler-ppc.cc

@@ -2894,8 +2894,10 @@ void TurboAssembler::SwapP(Register src, Register dst, Register scratch) {
 }
 
 void TurboAssembler::SwapP(Register src, MemOperand dst, Register scratch) {
-  if (dst.ra() != r0) DCHECK(!AreAliased(src, dst.ra(), scratch));
-  if (dst.rb() != r0) DCHECK(!AreAliased(src, dst.rb(), scratch));
+  if (dst.ra() != r0 && dst.ra().is_valid())
+    DCHECK(!AreAliased(src, dst.ra(), scratch));
+  if (dst.rb() != r0 && dst.rb().is_valid())
+    DCHECK(!AreAliased(src, dst.rb(), scratch));
   DCHECK(!AreAliased(src, scratch));
   mr(scratch, src);
   LoadP(src, dst, r0);