MIPS64 Fix load and store of float32 constant from/to stack

Tests that pointed out error are
cctest/test-code-generator/FuzzAssembleMove and
cctest/test-multiple-return/ReturnLastValueFloat32
on big endian architecture.

Change-Id: I47eb5d3b3aeffef4531f7961e94c0ccd7dece191
Reviewed-on: https://chromium-review.googlesource.com/1078755Reviewed-by: Ivica Bogosavljevic <ivica.bogosavljevic@mips.com>
Commit-Queue: Ivica Bogosavljevic <ivica.bogosavljevic@mips.com>
Cr-Commit-Position: refs/heads/master@{#53455}

src/compiler/mips64/code-generator-mips64.cc

@@ -10,6 +10,7 @@
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/osr.h"
 #include "src/heap/heap-inl.h"
+#include "src/mips64/constants-mips64.h"
 #include "src/mips64/macro-assembler-mips64.h"
 #include "src/optimized-compilation-info.h"
 
@@ -1786,7 +1787,9 @@ CodeGenerator::CodeGenResult CodeGenerator::AssembleArchInstruction(
           __ Ldc1(i.OutputDoubleRegister(), MemOperand(fp, offset));
         } else {
           DCHECK_EQ(op->representation(), MachineRepresentation::kFloat32);
-          __ lwc1(i.OutputSingleRegister(0), MemOperand(fp, offset));
+          __ lwc1(
+              i.OutputSingleRegister(0),
+              MemOperand(fp, offset + kLessSignificantWordInDoublewordOffset));
         }
       } else {
         __ Ld(i.OutputRegister(0), MemOperand(fp, offset));
@@ -3634,10 +3637,10 @@ void CodeGenerator::AssembleMove(InstructionOperand* source,
       if (destination->IsFPStackSlot()) {
         MemOperand dst = g.ToMemOperand(destination);
         if (bit_cast<int32_t>(src.ToFloat32()) == 0) {
-          __ Sw(zero_reg, dst);
+          __ Sd(zero_reg, dst);
         } else {
           __ li(kScratchReg, Operand(bit_cast<int32_t>(src.ToFloat32())));
-          __ Sw(kScratchReg, dst);
+          __ Sd(kScratchReg, dst);
         }
       } else {
         DCHECK(destination->IsFPRegister());

src/mips64/constants-mips64.h

@@ -84,8 +84,10 @@ const uint32_t kMipsSdlOffset = 0;
 
 #if defined(V8_TARGET_LITTLE_ENDIAN)
 const uint32_t kLeastSignificantByteInInt32Offset = 0;
+const uint32_t kLessSignificantWordInDoublewordOffset = 0;
 #elif defined(V8_TARGET_BIG_ENDIAN)
 const uint32_t kLeastSignificantByteInInt32Offset = 3;
+const uint32_t kLessSignificantWordInDoublewordOffset = 4;
 #else
 #error Unknown endianness
 #endif