[ic] [stubs] Don't use Code::flags in megamorphic stub cache hash computations.

src/ic/arm/stub-cache-arm.cc

 // Copyright 2012 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.
 
 #if V8_TARGET_ARCH_ARM
 
 #include "src/codegen.h"
 #include "src/ic/ic.h"
 #include "src/ic/stub-cache.h"
 #include "src/interface-descriptors.h"
 
 namespace v8 {
 namespace internal {
 
 #define __ ACCESS_MASM(masm)
 
 static void ProbeTable(StubCache* stub_cache, MacroAssembler* masm,
-                       Code::Flags flags, StubCache::Table table,
-                       Register receiver, Register name,
+                       StubCache::Table table, Register receiver, Register name,
                        // Number of the cache entry, not scaled.
                        Register offset, Register scratch, Register scratch2,
                        Register offset_scratch) {
   ExternalReference key_offset(stub_cache->key_reference(table));
   ExternalReference value_offset(stub_cache->value_reference(table));
   ExternalReference map_offset(stub_cache->map_reference(table));
 
   uint32_t key_off_addr = reinterpret_cast<uint32_t>(key_offset.address());
   uint32_t value_off_addr = reinterpret_cast<uint32_t>(value_offset.address());
   uint32_t map_off_addr = reinterpret_cast<uint32_t>(map_offset.address());
 
   // Check the relative positions of the address fields.
   DCHECK(value_off_addr > key_off_addr);
   DCHECK((value_off_addr - key_off_addr) % 4 == 0);
   DCHECK((value_off_addr - key_off_addr) < (256 * 4));
   DCHECK(map_off_addr > key_off_addr);
   DCHECK((map_off_addr - key_off_addr) % 4 == 0);
   DCHECK((map_off_addr - key_off_addr) < (256 * 4));
 
   Label miss;
   Register base_addr = scratch;
   scratch = no_reg;
 
   // Multiply by 3 because there are 3 fields per entry (name, code, map).
   __ add(offset_scratch, offset, Operand(offset, LSL, 1));
 
   // Calculate the base address of the entry.
-  __ mov(base_addr, Operand(key_offset));
-  __ add(base_addr, base_addr, Operand(offset_scratch, LSL, kPointerSizeLog2));
+  __ add(base_addr, offset_scratch, Operand(key_offset));
 
   // Check that the key in the entry matches the name.
   __ ldr(ip, MemOperand(base_addr, 0));
   __ cmp(name, ip);
   __ b(ne, &miss);
 
   // Check the map matches.
   __ ldr(ip, MemOperand(base_addr, map_off_addr - key_off_addr));
   __ ldr(scratch2, FieldMemOperand(receiver, HeapObject::kMapOffset));
   __ cmp(ip, scratch2);
   __ b(ne, &miss);
 
   // Get the code entry from the cache.
   Register code = scratch2;
   scratch2 = no_reg;
   __ ldr(code, MemOperand(base_addr, value_off_addr - key_off_addr));
 
+#ifdef DEBUG
   // Check that the flags match what we're looking for.
   Register flags_reg = base_addr;
   base_addr = no_reg;
   __ ldr(flags_reg, FieldMemOperand(code, Code::kFlagsOffset));
   // It's a nice optimization if this constant is encodable in the bic insn.
 
+  Code::Flags flags = Code::RemoveHolderFromFlags(
+      Code::ComputeHandlerFlags(stub_cache->ic_kind()));
   uint32_t mask = Code::kFlagsNotUsedInLookup;
   DCHECK(__ ImmediateFitsAddrMode1Instruction(mask));
   __ bic(flags_reg, flags_reg, Operand(mask));
   __ cmp(flags_reg, Operand(flags));
-  __ b(ne, &miss);
+  __ Check(eq, kUnexpectedValue);
 
-#ifdef DEBUG
   if (FLAG_test_secondary_stub_cache && table == StubCache::kPrimary) {
     __ jmp(&miss);
   } else if (FLAG_test_primary_stub_cache && table == StubCache::kSecondary) {
     __ jmp(&miss);
   }
 #endif
 
   // Jump to the first instruction in the code stub.
   __ add(pc, code, Operand(Code::kHeaderSize - kHeapObjectTag));
 
   // Miss: fall through.
   __ bind(&miss);
 }
 
 void StubCache::GenerateProbe(MacroAssembler* masm, Register receiver,
                               Register name, Register scratch, Register extra,
                               Register extra2, Register extra3) {
-  Code::Flags flags =
-      Code::RemoveHolderFromFlags(Code::ComputeHandlerFlags(ic_kind_));
-
   Label miss;
 
   // Make sure that code is valid. The multiplying code relies on the
   // entry size being 12.
   DCHECK(sizeof(Entry) == 12);
 
   // Make sure that there are no register conflicts.
   DCHECK(!AreAliased(receiver, name, scratch, extra, extra2, extra3));
 
   // Check scratch, extra and extra2 registers are valid.
@@ skipping 24 matching lines @@
   __ IncrementCounter(counters->megamorphic_stub_cache_probes(), 1, extra2,
                       extra3);
 
   // Check that the receiver isn't a smi.
   __ JumpIfSmi(receiver, &miss);
 
   // Get the map of the receiver and compute the hash.
   __ ldr(scratch, FieldMemOperand(name, Name::kHashFieldOffset));
   __ ldr(ip, FieldMemOperand(receiver, HeapObject::kMapOffset));
   __ add(scratch, scratch, Operand(ip));
-  uint32_t mask = kPrimaryTableSize - 1;
-  // We shift out the last two bits because they are not part of the hash and
-  // they are always 01 for maps.
-  __ mov(scratch, Operand(scratch, LSR, kCacheIndexShift));
-  // Mask down the eor argument to the minimum to keep the immediate
-  // ARM-encodable.
-  __ eor(scratch, scratch, Operand((flags >> kCacheIndexShift) & mask));
-  // Prefer and_ to ubfx here because ubfx takes 2 cycles.
-  __ and_(scratch, scratch, Operand(mask));
+  __ mov(ip, Operand(kPrimaryTableSize - 1));
+  __ and_(scratch, scratch, Operand(ip, LSL, kCacheIndexShift));
 
   // Probe the primary table.
-  ProbeTable(this, masm, flags, kPrimary, receiver, name, scratch, extra,
-             extra2, extra3);
+  ProbeTable(this, masm, kPrimary, receiver, name, scratch, extra, extra2,
+             extra3);
 
   // Primary miss: Compute hash for secondary probe.
-  __ sub(scratch, scratch, Operand(name, LSR, kCacheIndexShift));
-  uint32_t mask2 = kSecondaryTableSize - 1;
-  __ add(scratch, scratch, Operand((flags >> kCacheIndexShift) & mask2));
-  __ and_(scratch, scratch, Operand(mask2));
+  __ sub(scratch, scratch, Operand(name));
+  __ add(scratch, scratch, Operand(kSecondaryMagic));
+  __ mov(ip, Operand(kSecondaryTableSize - 1));
+  __ and_(scratch, scratch, Operand(ip, LSL, kCacheIndexShift));
 
   // Probe the secondary table.
-  ProbeTable(this, masm, flags, kSecondary, receiver, name, scratch, extra,
-             extra2, extra3);
+  ProbeTable(this, masm, kSecondary, receiver, name, scratch, extra, extra2,
+             extra3);
 
   // Cache miss: Fall-through and let caller handle the miss by
   // entering the runtime system.
   __ bind(&miss);
   __ IncrementCounter(counters->megamorphic_stub_cache_misses(), 1, extra2,
                       extra3);
 }
 
 
 #undef __
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM