Revert "Bit width analysis for avoiding conversion of bitops to unsigned."
TBR=sigmund@google.com
BUG=
Review URL: https://codereview.chromium.org/2510893002 .
diff --git a/pkg/compiler/lib/src/ssa/codegen.dart b/pkg/compiler/lib/src/ssa/codegen.dart
index 08a66d4..c882259 100644
--- a/pkg/compiler/lib/src/ssa/codegen.dart
+++ b/pkg/compiler/lib/src/ssa/codegen.dart
@@ -2,7 +2,6 @@
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
-import 'dart:math' as math;
import '../common.dart';
import '../common/codegen.dart' show CodegenRegistry, CodegenWorkItem;
import '../common/tasks.dart' show CompilerTask;
@@ -211,58 +210,8 @@
return false;
}
- // Returns the number of bits occupied by the value computed by [instruction].
- // Returns `32` if the value is negative or does not fit in a smaller number
- // of bits.
- int bitWidth(HInstruction instruction) {
- const int MAX = 32;
- int constant(HInstruction insn) {
- if (insn.isConstantInteger()) {
- IntConstantValue constant = insn.constant;
- return constant.primitiveValue;
- }
- return null;
- }
-
- if (instruction.isConstantInteger()) {
- int value = constant(instruction);
- if (value < 0) return MAX;
- if (value > ((1 << 31) - 1)) return MAX;
- return value.bitLength;
- }
- if (instruction is HBitAnd) {
- return math.min(bitWidth(instruction.left), bitWidth(instruction.right));
- }
- if (instruction is HBitOr || instruction is HBitXor) {
- int leftWidth = bitWidth(instruction.left);
- if (leftWidth == MAX) return MAX;
- return math.max(leftWidth, bitWidth(instruction.right));
- }
- if (instruction is HShiftLeft) {
- int shiftCount = constant(instruction.right);
- if (shiftCount == null || shiftCount < 0 || shiftCount > 31) return MAX;
- int leftWidth = bitWidth(instruction.left);
- int width = leftWidth + shiftCount;
- return math.min(width, MAX);
- }
- if (instruction is HShiftRight) {
- int shiftCount = constant(instruction.right);
- if (shiftCount == null || shiftCount < 0 || shiftCount > 31) return MAX;
- int leftWidth = bitWidth(instruction.left);
- if (leftWidth >= MAX) return MAX;
- return math.max(leftWidth - shiftCount, 0);
- }
- if (instruction is HAdd) {
- return math.min(
- 1 + math.max(bitWidth(instruction.left), bitWidth(instruction.right)),
- MAX);
- }
- return MAX;
- }
-
bool requiresUintConversion(instruction) {
if (instruction.isUInt31(compiler)) return false;
- if (bitWidth(instruction) <= 31) return false;
// If the result of a bit-operation is only used by other bit
// operations, we do not have to convert to an unsigned integer.
return hasNonBitOpUser(instruction, new Set<HPhi>());
