ARM64: Fix SHR logic error.

src/arm64/lithium-codegen-arm64.cc

 // Copyright 2013 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/v8.h"
 
 #include "src/arm64/lithium-codegen-arm64.h"
 #include "src/arm64/lithium-gap-resolver-arm64.h"
 #include "src/code-stubs.h"
 #include "src/hydrogen-osr.h"
@@ skipping 4873 matching lines @@
   Register left = ToRegister32(instr->left());
   Register result = ToRegister32(instr->result());
 
   if (right_op->IsRegister()) {
     Register right = ToRegister32(instr->right());
     switch (instr->op()) {
       case Token::ROR: __ Ror(result, left, right); break;
       case Token::SAR: __ Asr(result, left, right); break;
       case Token::SHL: __ Lsl(result, left, right); break;
       case Token::SHR:
+        __ Lsr(result, left, right);
         if (instr->can_deopt()) {
-          Label right_not_zero;
-          __ Cbnz(right, &right_not_zero);
-          DeoptimizeIfNegative(left, instr->environment());
-          __ Bind(&right_not_zero);
+          // If `left >>> right` >= 0x80000000, the result is not representable
+          // in a signed 32-bit smi.
+          DeoptimizeIfNegative(result, instr->environment());
         }
-        __ Lsr(result, left, right);
         break;
       default: UNREACHABLE();
     }
   } else {
     DCHECK(right_op->IsConstantOperand());
     int shift_count = JSShiftAmountFromLConstant(right_op);
     if (shift_count == 0) {
       if ((instr->op() == Token::SHR) && instr->can_deopt()) {
         DeoptimizeIfNegative(left, instr->environment());
       }
@@ skipping 34 matching lines @@
       case Token::SAR:
         __ Ubfx(result, right, kSmiShift, 5);
         __ Asr(result, left, result);
         __ Bic(result, result, kSmiShiftMask);
         break;
       case Token::SHL:
         __ Ubfx(result, right, kSmiShift, 5);
         __ Lsl(result, left, result);
         break;
       case Token::SHR:
-        if (instr->can_deopt()) {
-          Label right_not_zero;
-          __ Cbnz(right, &right_not_zero);
-          DeoptimizeIfNegative(left, instr->environment());
-          __ Bind(&right_not_zero);
-        }
         __ Ubfx(result, right, kSmiShift, 5);
         __ Lsr(result, left, result);
         __ Bic(result, result, kSmiShiftMask);
+        if (instr->can_deopt()) {
+          // If `left >>> right` >= 0x80000000, the result is not representable
+          // in a signed 32-bit smi.
+          DeoptimizeIfNegative(result, instr->environment());
+        }
         break;
       default: UNREACHABLE();
     }
   } else {
     DCHECK(right_op->IsConstantOperand());
     int shift_count = JSShiftAmountFromLConstant(right_op);
     if (shift_count == 0) {
       if ((instr->op() == Token::SHR) && instr->can_deopt()) {
         DeoptimizeIfNegative(left, instr->environment());
       }
@@ skipping 1053 matching lines @@
   Handle<ScopeInfo> scope_info = instr->scope_info();
   __ Push(scope_info);
   __ Push(ToRegister(instr->function()));
   CallRuntime(Runtime::kPushBlockContext, 2, instr);
   RecordSafepoint(Safepoint::kNoLazyDeopt);
 }
 
 
 
 } }  // namespace v8::internal