There was a bug in older Cortex-A53, however in newer versions of Cortex-A53,
webkit fails to build.  The code is removed for newer versions of Cortex-A53.   
See https://bugs.webkit.org/show_bug.cgi?id=197192

From: Brian Woodcox <bw@InSkyData.com>
Date: March 18, 2020

--- a/Source/JavaScriptCore/assembler/ARM64Assembler.h
+++ a/Source/JavaScriptCore/assembler/ARM64Assembler.h
@@ -740,7 +740,6 @@
     {
         ASSERT(!(offset & 0xfff));
         insn(pcRelative(true, offset >> 12, rd));
-        nopCortexA53Fix843419();
     }
 
     template<int datasize, SetFlags setFlags = DontSetFlags>
@@ -1390,7 +1389,6 @@
     ALWAYS_INLINE void madd(RegisterID rd, RegisterID rn, RegisterID rm, RegisterID ra)
     {
         CHECK_DATASIZE();
-        nopCortexA53Fix835769<datasize>();
         insn(dataProcessing3Source(DATASIZE, DataOp_MADD, rm, ra, rn, rd));
     }
 
@@ -1443,7 +1441,6 @@
     ALWAYS_INLINE void msub(RegisterID rd, RegisterID rn, RegisterID rm, RegisterID ra)
     {
         CHECK_DATASIZE();
-        nopCortexA53Fix835769<datasize>();
         insn(dataProcessing3Source(DATASIZE, DataOp_MSUB, rm, ra, rn, rd));
     }
 
@@ -1691,7 +1688,6 @@
 
     ALWAYS_INLINE void smaddl(RegisterID rd, RegisterID rn, RegisterID rm, RegisterID ra)
     {
-        nopCortexA53Fix835769<64>();
         insn(dataProcessing3Source(Datasize_64, DataOp_SMADDL, rm, ra, rn, rd));
     }
 
@@ -1702,7 +1698,6 @@
 
     ALWAYS_INLINE void smsubl(RegisterID rd, RegisterID rn, RegisterID rm, RegisterID ra)
     {
-        nopCortexA53Fix835769<64>();
         insn(dataProcessing3Source(Datasize_64, DataOp_SMSUBL, rm, ra, rn, rd));
     }
 
@@ -1960,7 +1955,6 @@
 
     ALWAYS_INLINE void umaddl(RegisterID rd, RegisterID rn, RegisterID rm, RegisterID ra)
     {
-        nopCortexA53Fix835769<64>();
         insn(dataProcessing3Source(Datasize_64, DataOp_UMADDL, rm, ra, rn, rd));
     }
 
@@ -1971,7 +1965,6 @@
 
     ALWAYS_INLINE void umsubl(RegisterID rd, RegisterID rn, RegisterID rm, RegisterID ra)
     {
-        nopCortexA53Fix835769<64>();
         insn(dataProcessing3Source(Datasize_64, DataOp_UMSUBL, rm, ra, rn, rd));
     }
 
@@ -3691,37 +3684,6 @@
         return 0x1e7e0000 | (dn << 5) | rd;
     }
 
-    // Workaround for Cortex-A53 erratum (835769). Emit an extra nop if the
-    // last instruction in the buffer is a load, store or prefetch. Needed
-    // before 64-bit multiply-accumulate instructions.
-    template<int datasize>
-    ALWAYS_INLINE void nopCortexA53Fix835769()
-    {
-#if CPU(ARM64_CORTEXA53)
-        CHECK_DATASIZE();
-        if (datasize == 64) {
-            if (LIKELY(m_buffer.codeSize() >= sizeof(int32_t))) {
-                // From ARMv8 Reference Manual, Section C4.1: the encoding of the
-                // instructions in the Loads and stores instruction group is:
-                // ---- 1-0- ---- ---- ---- ---- ---- ----
-                if (UNLIKELY((*reinterpret_cast_ptr<int32_t*>(reinterpret_cast_ptr<char*>(m_buffer.data()) + m_buffer.codeSize() - sizeof(int32_t)) & 0x0a000000) == 0x08000000))
-                    nop();
-            }
-        }
-#endif
-    }
-
-    // Workaround for Cortex-A53 erratum (843419). Emit extra nops to avoid
-    // wrong address access after ADRP instruction.
-    ALWAYS_INLINE void nopCortexA53Fix843419()
-    {
-#if CPU(ARM64_CORTEXA53)
-        nop();
-        nop();
-        nop();
-#endif
-    }
-
     Vector<LinkRecord, 0, UnsafeVectorOverflow> m_jumpsToLink;
     int m_indexOfLastWatchpoint;
     int m_indexOfTailOfLastWatchpoint;
--- a/Source/JavaScriptCore/offlineasm/arm64.rb
+++ a/Source/JavaScriptCore/offlineasm/arm64.rb
@@ -351,33 +351,6 @@
     newList
 end
 
-# Workaround for Cortex-A53 erratum (835769)
-def arm64CortexA53Fix835769(list)
-    newList = []
-    lastOpcodeUnsafe = false
-
-    list.each {
-        | node |
-        if node.is_a? Instruction
-            case node.opcode
-            when /^store/, /^load/
-                # List all macro instructions that can be lowered to a load, store or prefetch ARM64 assembly instruction
-                lastOpcodeUnsafe = true
-            when  "muli", "mulp", "mulq", "smulli"
-                # List all macro instructions that can be lowered to a 64-bit multiply-accumulate ARM64 assembly instruction
-                # (defined as one of MADD, MSUB, SMADDL, SMSUBL, UMADDL or UMSUBL).
-                if lastOpcodeUnsafe
-                    newList << Instruction.new(node.codeOrigin, "nopCortexA53Fix835769", [])
-                end
-                lastOpcodeUnsafe = false
-            else
-                lastOpcodeUnsafe = false
-            end
-        end
-        newList << node
-    }
-    newList
-end
 
 class Sequence
     def getModifiedListARM64(result = @list)
@@ -470,7 +443,6 @@
         result = arm64FixSpecialRegisterArithmeticMode(result)
         result = assignRegistersToTemporaries(result, :gpr, ARM64_EXTRA_GPRS)
         result = assignRegistersToTemporaries(result, :fpr, ARM64_EXTRA_FPRS)
-        result = arm64CortexA53Fix835769(result)
         return result
     end
 end
@@ -1115,10 +1087,6 @@
             $asm.puts "bfi #{operands[3].arm64Operand(:quad)}, #{operands[0].arm64Operand(:quad)}, #{operands[1].value}, #{operands[2].value}"
         when "pcrtoaddr"
             $asm.puts "adr #{operands[1].arm64Operand(:quad)}, #{operands[0].value}"
-        when "nopCortexA53Fix835769"
-            $asm.putStr("#if CPU(ARM64_CORTEXA53)")
-            $asm.puts "nop"
-            $asm.putStr("#endif")
         when "globaladdr"
             uid = $asm.newUID
 
--- a/Source/JavaScriptCore/offlineasm/instructions.rb
+++ a/Source/JavaScriptCore/offlineasm/instructions.rb
@@ -354,7 +354,6 @@
     [
      "bfiq", # Bit field insert <source reg> <last bit written> <width immediate> <dest reg>
      "pcrtoaddr",   # Address from PC relative offset - adr instruction
-     "nopFixCortexA53Err835769", # nop on Cortex-A53 (nothing otherwise)
      "globaladdr",
      "divi",
      "divis",
--- a/Source/cmake/OptionsCommon.cmake
+++ a/Source/cmake/OptionsCommon.cmake
@@ -19,32 +19,6 @@
 set_property(GLOBAL PROPERTY USE_FOLDERS ON)
 define_property(TARGET PROPERTY FOLDER INHERITED BRIEF_DOCS "folder" FULL_DOCS "IDE folder name")
 
-# Detect Cortex-A53 core if CPU is ARM64 and OS is Linux.
-# Query /proc/cpuinfo for each available core and check reported CPU part number: 0xd03 signals Cortex-A53.
-# (see Main ID Register in ARM Cortex-A53 MPCore Processor Technical Reference Manual)
-set(WTF_CPU_ARM64_CORTEXA53_INITIALVALUE OFF)
-if (WTF_CPU_ARM64 AND (${CMAKE_SYSTEM_NAME} STREQUAL "Linux"))
-    execute_process(COMMAND nproc OUTPUT_VARIABLE PROC_COUNT)
-    math(EXPR PROC_MAX ${PROC_COUNT}-1)
-    foreach (PROC_ID RANGE ${PROC_MAX})
-        execute_process(COMMAND taskset -c ${PROC_ID} grep "^CPU part" /proc/cpuinfo OUTPUT_VARIABLE PROC_PART)
-        if (PROC_PART MATCHES "0xd03")
-            set(WTF_CPU_ARM64_CORTEXA53_INITIALVALUE ON)
-            break ()
-        endif ()
-    endforeach ()
-endif ()
-option(WTF_CPU_ARM64_CORTEXA53 "Enable Cortex-A53-specific code paths" ${WTF_CPU_ARM64_CORTEXA53_INITIALVALUE})
-
-if (WTF_CPU_ARM64_CORTEXA53)
-    if (NOT WTF_CPU_ARM64)
-        message(FATAL_ERROR "WTF_CPU_ARM64_CORTEXA53 set without WTF_CPU_ARM64")
-    endif ()
-    WEBKIT_PREPEND_GLOBAL_COMPILER_FLAGS(-mfix-cortex-a53-835769)
-endif ()
-
-EXPOSE_VARIABLE_TO_BUILD(WTF_CPU_ARM64_CORTEXA53)
-
 set(ARM_TRADITIONAL_DETECTED FALSE)
 if (WTF_CPU_ARM)
     set(ARM_THUMB2_TEST_SOURCE