Do not overwrite an input register in shift operations.
'second_reg' is an input register that can survive the instruction.
Instead use the output register as a temporary result.
bug:21667432
Change-Id: I1a4577b0333c3fb184645023d5eae30555bbf65c
diff --git a/compiler/optimizing/code_generator_arm.cc b/compiler/optimizing/code_generator_arm.cc
index bd0bfcd..0fa38c0 100644
--- a/compiler/optimizing/code_generator_arm.cc
+++ b/compiler/optimizing/code_generator_arm.cc
@@ -2616,7 +2616,9 @@
case Primitive::kPrimInt: {
locations->SetInAt(0, Location::RequiresRegister());
locations->SetInAt(1, Location::RegisterOrConstant(op->InputAt(1)));
- locations->SetOut(Location::RequiresRegister(), Location::kNoOutputOverlap);
+ // Make the output overlap, as it will be used to hold the masked
+ // second input.
+ locations->SetOut(Location::RequiresRegister(), Location::kOutputOverlap);
break;
}
case Primitive::kPrimLong: {
@@ -2647,13 +2649,13 @@
// Arm doesn't mask the shift count so we need to do it ourselves.
if (second.IsRegister()) {
Register second_reg = second.AsRegister<Register>();
- __ and_(second_reg, second_reg, ShifterOperand(kMaxIntShiftValue));
+ __ and_(out_reg, second_reg, ShifterOperand(kMaxIntShiftValue));
if (op->IsShl()) {
- __ Lsl(out_reg, first_reg, second_reg);
+ __ Lsl(out_reg, first_reg, out_reg);
} else if (op->IsShr()) {
- __ Asr(out_reg, first_reg, second_reg);
+ __ Asr(out_reg, first_reg, out_reg);
} else {
- __ Lsr(out_reg, first_reg, second_reg);
+ __ Lsr(out_reg, first_reg, out_reg);
}
} else {
int32_t cst = second.GetConstant()->AsIntConstant()->GetValue();
@@ -2682,44 +2684,44 @@
Register second_reg = second.AsRegister<Register>();
if (op->IsShl()) {
+ __ and_(o_l, second_reg, ShifterOperand(kMaxLongShiftValue));
// Shift the high part
- __ and_(second_reg, second_reg, ShifterOperand(63));
- __ Lsl(o_h, high, second_reg);
+ __ Lsl(o_h, high, o_l);
// Shift the low part and `or` what overflew on the high part
- __ rsb(temp, second_reg, ShifterOperand(32));
+ __ rsb(temp, o_l, ShifterOperand(kArmBitsPerWord));
__ Lsr(temp, low, temp);
__ orr(o_h, o_h, ShifterOperand(temp));
// If the shift is > 32 bits, override the high part
- __ subs(temp, second_reg, ShifterOperand(32));
+ __ subs(temp, o_l, ShifterOperand(kArmBitsPerWord));
__ it(PL);
__ Lsl(o_h, low, temp, false, PL);
// Shift the low part
- __ Lsl(o_l, low, second_reg);
+ __ Lsl(o_l, low, o_l);
} else if (op->IsShr()) {
+ __ and_(o_h, second_reg, ShifterOperand(kMaxLongShiftValue));
// Shift the low part
- __ and_(second_reg, second_reg, ShifterOperand(63));
- __ Lsr(o_l, low, second_reg);
+ __ Lsr(o_l, low, o_h);
// Shift the high part and `or` what underflew on the low part
- __ rsb(temp, second_reg, ShifterOperand(32));
+ __ rsb(temp, o_h, ShifterOperand(kArmBitsPerWord));
__ Lsl(temp, high, temp);
__ orr(o_l, o_l, ShifterOperand(temp));
// If the shift is > 32 bits, override the low part
- __ subs(temp, second_reg, ShifterOperand(32));
+ __ subs(temp, o_h, ShifterOperand(kArmBitsPerWord));
__ it(PL);
__ Asr(o_l, high, temp, false, PL);
// Shift the high part
- __ Asr(o_h, high, second_reg);
+ __ Asr(o_h, high, o_h);
} else {
+ __ and_(o_h, second_reg, ShifterOperand(kMaxLongShiftValue));
// same as Shr except we use `Lsr`s and not `Asr`s
- __ and_(second_reg, second_reg, ShifterOperand(63));
- __ Lsr(o_l, low, second_reg);
- __ rsb(temp, second_reg, ShifterOperand(32));
+ __ Lsr(o_l, low, o_h);
+ __ rsb(temp, o_h, ShifterOperand(kArmBitsPerWord));
__ Lsl(temp, high, temp);
__ orr(o_l, o_l, ShifterOperand(temp));
- __ subs(temp, second_reg, ShifterOperand(32));
+ __ subs(temp, o_h, ShifterOperand(kArmBitsPerWord));
__ it(PL);
__ Lsr(o_l, high, temp, false, PL);
- __ Lsr(o_h, high, second_reg);
+ __ Lsr(o_h, high, o_h);
}
break;
}
diff --git a/compiler/optimizing/code_generator_arm.h b/compiler/optimizing/code_generator_arm.h
index 5b4b375..953e733 100644
--- a/compiler/optimizing/code_generator_arm.h
+++ b/compiler/optimizing/code_generator_arm.h
@@ -32,6 +32,7 @@
// Use a local definition to prevent copying mistakes.
static constexpr size_t kArmWordSize = kArmPointerSize;
+static constexpr size_t kArmBitsPerWord = kArmWordSize * kBitsPerByte;
static constexpr Register kParameterCoreRegisters[] = { R1, R2, R3 };
static constexpr size_t kParameterCoreRegistersLength = arraysize(kParameterCoreRegisters);