Revert of Add SIMD 128 alignment support to Heap. (patchset #3 id:40001 of...

Revert of Add SIMD 128 alignment support to Heap. (patchset #3 id:40001 of https://codereview.chromium.org/1159453004/)

Reason for revert:
Breaks Linux - arm64 - sim - MSAN
TBR=jochen

Original issue's description:
> Add SIMD 128 alignment support to Heap.
> Adds SIMD 128 alignment sizes and masks.
> Adds support in Heap for SIMD alignments and fills.
> Reworks cctest so that each test independently aligns its allocation address, rather than depending on the previous tests ending state. Adds test cases for SIMD.
>
> LOG=N
> BUG=v8:4124

TBR=hpayer@chromium.org,jochen@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:4124

Review URL: https://codereview.chromium.org/1169453003

Cr-Commit-Position: refs/heads/master@{#28768}

src/globals.h

@@ -197,8 +197,6 @@ typedef int32_t uc32;
 const int kOneByteSize    = kCharSize;
 const int kUC16Size     = sizeof(uc16);      // NOLINT
 
-// 128 bit SIMD value size.
-const int kSimd128Size = 16;
 
 // Round up n to be a multiple of sz, where sz is a power of 2.
 #define ROUND_UP(n, sz) (((n) + ((sz) - 1)) & ~((sz) - 1))
@@ -311,10 +309,6 @@ const intptr_t kPointerAlignmentMask = kPointerAlignment - 1;
 const intptr_t kDoubleAlignment = 8;
 const intptr_t kDoubleAlignmentMask = kDoubleAlignment - 1;
 
-// Desired alignment for 128 bit SIMD values.
-const intptr_t kSimd128Alignment = 16;
-const intptr_t kSimd128AlignmentMask = kSimd128Alignment - 1;
-
 // Desired alignment for generated code is 32 bytes (to improve cache line
 // utilization).
 const int kCodeAlignmentBits = 5;
@@ -455,12 +449,7 @@ enum AllocationSpace {
 const int kSpaceTagSize = 3;
 const int kSpaceTagMask = (1 << kSpaceTagSize) - 1;
 
-enum AllocationAlignment {
-  kWordAligned,
-  kDoubleAligned,
-  kDoubleUnaligned,
-  kSimd128Unaligned
-};
+enum AllocationAlignment { kWordAligned, kDoubleAligned, kDoubleUnaligned };
 
 // A flag that indicates whether objects should be pretenured when
 // allocated (allocated directly into the old generation) or not

src/heap/heap.cc

@@ -1995,8 +1995,6 @@ int Heap::GetMaximumFillToAlign(AllocationAlignment alignment) {
     case kDoubleAligned:
     case kDoubleUnaligned:
       return kDoubleSize - kPointerSize;
-    case kSimd128Unaligned:
-      return kSimd128Size - kPointerSize;
     default:
       UNREACHABLE();
   }
@@ -2010,10 +2008,6 @@ int Heap::GetFillToAlign(Address address, AllocationAlignment alignment) {
     return kPointerSize;
   if (alignment == kDoubleUnaligned && (offset & kDoubleAlignmentMask) == 0)
     return kDoubleSize - kPointerSize;  // No fill if double is always aligned.
-  if (alignment == kSimd128Unaligned) {
-    return (kSimd128Size - (static_cast<int>(offset) + kPointerSize)) &
-           kSimd128AlignmentMask;
-  }
   return 0;
 }