A64: Let the MacroAssembler resolve branches to distant targets.

src/a64/instructions-a64.h

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 262 matching lines @@
       return UncondBranchType;
     } else if (IsCompareBranch()) {
       return CompareBranchType;
     } else if (IsTestBranch()) {
       return TestBranchType;
     } else {
       return UnknownBranchType;
     }
   }
 
+  static int ImmBranchRangeBitwidth(ImmBranchType branch_type) {
+    switch (branch_type) {
+      case UncondBranchType:
+        return ImmUncondBranch_width;
+      case CondBranchType:
+        return ImmCondBranch_width;
+      case CompareBranchType:
+        return ImmCmpBranch_width;
+      case TestBranchType:
+        return ImmTestBranch_width;
+      default:
+        UNREACHABLE();
+        return 0;
+    }
+  }
+
+  // The range of the branch instruction, expressed as 'instr +- range'.
+  static int32_t ImmBranchRange(ImmBranchType branch_type) {
+    return
+      (1 << (ImmBranchRangeBitwidth(branch_type) + kInstructionSizeLog2)) / 2 -
+      kInstructionSize;
+  }
+
   int ImmBranch() const {
     switch (BranchType()) {
       case CondBranchType: return ImmCondBranch();
       case UncondBranchType: return ImmUncondBranch();
       case CompareBranchType: return ImmCmpBranch();
       case TestBranchType: return ImmTestBranch();
       default: UNREACHABLE();
     }
     return 0;
   }
@@ skipping 29 matching lines @@
 
   // Find the PC offset encoded in this instruction. 'this' may be a branch or
   // a PC-relative addressing instruction.
   // The offset returned is unscaled.
   ptrdiff_t ImmPCOffset();
 
   // Find the target of this instruction. 'this' may be a branch or a
   // PC-relative addressing instruction.
   Instruction* ImmPCOffsetTarget();
 
+  static bool IsValidImmPCOffset(ImmBranchType branch_type, int32_t offset);
+  bool IsTargetInImmPCOffsetRange(Instruction* target);
   // Patch a PC-relative offset to refer to 'target'. 'this' may be a branch or
   // a PC-relative addressing instruction.
   void SetImmPCOffsetTarget(Instruction* target);
   // Patch a literal load instruction to load from 'source'.
   void SetImmLLiteral(Instruction* source);
 
   uint8_t* LiteralAddress() {
     int offset = ImmLLiteral() << kLiteralEntrySizeLog2;
     return reinterpret_cast<uint8_t*>(this) + offset;
   }
@@ skipping 140 matching lines @@
   TRACE_ENABLE   = 1 << 6,
   TRACE_DISABLE  = 2 << 6,
   TRACE_OVERRIDE = 3 << 6
 };
 
 
 } }  // namespace v8::internal
 
 
 #endif  // V8_A64_INSTRUCTIONS_A64_H_