[turbofan] Reland of `Add alignment parameter to StackSlot operator`

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

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/code-generator.h"
 #include "src/compilation-info.h"
 #include "src/compiler/code-generator-impl.h"
 #include "src/compiler/gap-resolver.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/osr.h"
@@ skipping 757 matching lines @@
       __ sw(value, MemOperand(at));
       __ CheckPageFlag(object, scratch0,
                        MemoryChunk::kPointersFromHereAreInterestingMask, ne,
                        ool->entry());
       __ bind(ool->exit());
       break;
     }
     case kArchStackSlot: {
       FrameOffset offset =
           frame_access_state()->GetFrameOffset(i.InputInt32(0));
-      __ Addu(i.OutputRegister(), offset.from_stack_pointer() ? sp : fp,
-              Operand(offset.offset()));
+      Register base_reg = offset.from_stack_pointer() ? sp : fp;
+      __ Addu(i.OutputRegister(), base_reg, Operand(offset.offset()));
+      int alignment = i.InputInt32(1);
+      DCHECK(alignment == 0 || alignment == 4 || alignment == 8 ||
+             alignment == 16);
+      if (FLAG_debug_code && alignment > 0) {
+        // Verify that the output_register is properly aligned
+        __ And(kScratchReg, i.OutputRegister(), Operand(kPointerSize - 1));
+        __ Assert(eq, kAllocationIsNotDoubleAligned, kScratchReg,
+                  Operand(zero_reg));
+      }
+
+      if (alignment == 2 * kPointerSize) {
+        Label done;
+        __ Addu(kScratchReg, base_reg, Operand(offset.offset()));
+        __ And(kScratchReg, kScratchReg, Operand(alignment - 1));
+        __ BranchShort(&done, eq, kScratchReg, Operand(zero_reg));
+        __ Addu(i.OutputRegister(), i.OutputRegister(), kPointerSize);
+        __ bind(&done);
+      } else if (alignment > 2 * kPointerSize) {
+        Label done;
+        __ Addu(kScratchReg, base_reg, Operand(offset.offset()));
+        __ And(kScratchReg, kScratchReg, Operand(alignment - 1));
+        __ BranchShort(&done, eq, kScratchReg, Operand(zero_reg));
+        __ li(kScratchReg2, alignment);
+        __ Subu(kScratchReg2, kScratchReg2, Operand(kScratchReg));
+        __ Addu(i.OutputRegister(), i.OutputRegister(), kScratchReg2);
+        __ bind(&done);
+      }
       break;
     }
     case kIeee754Float64Acos:
       ASSEMBLE_IEEE754_UNOP(acos);
       break;
     case kIeee754Float64Acosh:
       ASSEMBLE_IEEE754_UNOP(acosh);
       break;
     case kIeee754Float64Asin:
       ASSEMBLE_IEEE754_UNOP(asin);
@@ skipping 1949 matching lines @@
       padding_size -= v8::internal::Assembler::kInstrSize;
     }
   }
 }
 
 #undef __
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8