Optimizing: Fix long-to-fp conversion on x86.
long-to-fp conversion implemented using SSE loses the precision.
The test is included. CL uses FPU to provide the correct result.
Change-Id: I8eaf3c46819a8cb52642a7e7d7c4e3e0edbc88db
Signed-off-by: Serguei Katkov <serguei.i.katkov@intel.com>
diff --git a/compiler/optimizing/code_generator_x86.cc b/compiler/optimizing/code_generator_x86.cc
index 92b62e2..ef896aa 100644
--- a/compiler/optimizing/code_generator_x86.cc
+++ b/compiler/optimizing/code_generator_x86.cc
@@ -1525,10 +1525,8 @@
case Primitive::kPrimLong:
// Processing a Dex `long-to-float' instruction.
- locations->SetInAt(0, Location::RequiresRegister());
- locations->SetOut(Location::RequiresFpuRegister());
- locations->AddTemp(Location::RequiresFpuRegister());
- locations->AddTemp(Location::RequiresFpuRegister());
+ locations->SetInAt(0, Location::Any());
+ locations->SetOut(Location::Any());
break;
case Primitive::kPrimDouble:
@@ -1558,10 +1556,8 @@
case Primitive::kPrimLong:
// Processing a Dex `long-to-double' instruction.
- locations->SetInAt(0, Location::RequiresRegister());
- locations->SetOut(Location::RequiresFpuRegister());
- locations->AddTemp(Location::RequiresFpuRegister());
- locations->AddTemp(Location::RequiresFpuRegister());
+ locations->SetInAt(0, Location::Any());
+ locations->SetOut(Location::Any());
break;
case Primitive::kPrimFloat:
@@ -1782,37 +1778,31 @@
case Primitive::kPrimLong: {
// Processing a Dex `long-to-float' instruction.
- Register low = in.AsRegisterPairLow<Register>();
- Register high = in.AsRegisterPairHigh<Register>();
- XmmRegister result = out.AsFpuRegister<XmmRegister>();
- XmmRegister temp = locations->GetTemp(0).AsFpuRegister<XmmRegister>();
- XmmRegister constant = locations->GetTemp(1).AsFpuRegister<XmmRegister>();
+ size_t adjustment = 0;
- // Operations use doubles for precision reasons (each 32-bit
- // half of a long fits in the 53-bit mantissa of a double,
- // but not in the 24-bit mantissa of a float). This is
- // especially important for the low bits. The result is
- // eventually converted to float.
+ // Create stack space for the call to
+ // InstructionCodeGeneratorX86::PushOntoFPStack and/or X86Assembler::fstps below.
+ // TODO: enhance register allocator to ask for stack temporaries.
+ if (!in.IsDoubleStackSlot() || !out.IsStackSlot()) {
+ adjustment = Primitive::ComponentSize(Primitive::kPrimLong);
+ __ subl(ESP, Immediate(adjustment));
+ }
- // low = low - 2^31 (to prevent bit 31 of `low` to be
- // interpreted as a sign bit)
- __ subl(low, Immediate(0x80000000));
- // temp = int-to-double(high)
- __ cvtsi2sd(temp, high);
- // temp = temp * 2^32
- __ LoadLongConstant(constant, k2Pow32EncodingForDouble);
- __ mulsd(temp, constant);
- // result = int-to-double(low)
- __ cvtsi2sd(result, low);
- // result = result + 2^31 (restore the original value of `low`)
- __ LoadLongConstant(constant, k2Pow31EncodingForDouble);
- __ addsd(result, constant);
- // result = result + temp
- __ addsd(result, temp);
- // result = double-to-float(result)
- __ cvtsd2ss(result, result);
- // Restore low.
- __ addl(low, Immediate(0x80000000));
+ // Load the value to the FP stack, using temporaries if needed.
+ PushOntoFPStack(in, 0, adjustment, false, true);
+
+ if (out.IsStackSlot()) {
+ __ fstps(Address(ESP, out.GetStackIndex() + adjustment));
+ } else {
+ __ fstps(Address(ESP, 0));
+ Location stack_temp = Location::StackSlot(0);
+ codegen_->Move32(out, stack_temp);
+ }
+
+ // Remove the temporary stack space we allocated.
+ if (adjustment != 0) {
+ __ addl(ESP, Immediate(adjustment));
+ }
break;
}
@@ -1841,29 +1831,31 @@
case Primitive::kPrimLong: {
// Processing a Dex `long-to-double' instruction.
- Register low = in.AsRegisterPairLow<Register>();
- Register high = in.AsRegisterPairHigh<Register>();
- XmmRegister result = out.AsFpuRegister<XmmRegister>();
- XmmRegister temp = locations->GetTemp(0).AsFpuRegister<XmmRegister>();
- XmmRegister constant = locations->GetTemp(1).AsFpuRegister<XmmRegister>();
+ size_t adjustment = 0;
- // low = low - 2^31 (to prevent bit 31 of `low` to be
- // interpreted as a sign bit)
- __ subl(low, Immediate(0x80000000));
- // temp = int-to-double(high)
- __ cvtsi2sd(temp, high);
- // temp = temp * 2^32
- __ LoadLongConstant(constant, k2Pow32EncodingForDouble);
- __ mulsd(temp, constant);
- // result = int-to-double(low)
- __ cvtsi2sd(result, low);
- // result = result + 2^31 (restore the original value of `low`)
- __ LoadLongConstant(constant, k2Pow31EncodingForDouble);
- __ addsd(result, constant);
- // result = result + temp
- __ addsd(result, temp);
- // Restore low.
- __ addl(low, Immediate(0x80000000));
+ // Create stack space for the call to
+ // InstructionCodeGeneratorX86::PushOntoFPStack and/or X86Assembler::fstpl below.
+ // TODO: enhance register allocator to ask for stack temporaries.
+ if (!in.IsDoubleStackSlot() || !out.IsDoubleStackSlot()) {
+ adjustment = Primitive::ComponentSize(Primitive::kPrimLong);
+ __ subl(ESP, Immediate(adjustment));
+ }
+
+ // Load the value to the FP stack, using temporaries if needed.
+ PushOntoFPStack(in, 0, adjustment, false, true);
+
+ if (out.IsDoubleStackSlot()) {
+ __ fstpl(Address(ESP, out.GetStackIndex() + adjustment));
+ } else {
+ __ fstpl(Address(ESP, 0));
+ Location stack_temp = Location::DoubleStackSlot(0);
+ codegen_->Move64(out, stack_temp);
+ }
+
+ // Remove the temporary stack space we allocated.
+ if (adjustment != 0) {
+ __ addl(ESP, Immediate(adjustment));
+ }
break;
}
@@ -2203,24 +2195,43 @@
}
}
-void InstructionCodeGeneratorX86::PushOntoFPStack(Location source, uint32_t temp_offset,
- uint32_t stack_adjustment, bool is_float) {
+void InstructionCodeGeneratorX86::PushOntoFPStack(Location source,
+ uint32_t temp_offset,
+ uint32_t stack_adjustment,
+ bool is_fp,
+ bool is_wide) {
if (source.IsStackSlot()) {
- DCHECK(is_float);
- __ flds(Address(ESP, source.GetStackIndex() + stack_adjustment));
+ DCHECK(!is_wide);
+ if (is_fp) {
+ __ flds(Address(ESP, source.GetStackIndex() + stack_adjustment));
+ } else {
+ __ filds(Address(ESP, source.GetStackIndex() + stack_adjustment));
+ }
} else if (source.IsDoubleStackSlot()) {
- DCHECK(!is_float);
- __ fldl(Address(ESP, source.GetStackIndex() + stack_adjustment));
+ DCHECK(is_wide);
+ if (is_fp) {
+ __ fldl(Address(ESP, source.GetStackIndex() + stack_adjustment));
+ } else {
+ __ fildl(Address(ESP, source.GetStackIndex() + stack_adjustment));
+ }
} else {
// Write the value to the temporary location on the stack and load to FP stack.
- if (is_float) {
+ if (!is_wide) {
Location stack_temp = Location::StackSlot(temp_offset);
codegen_->Move32(stack_temp, source);
- __ flds(Address(ESP, temp_offset));
+ if (is_fp) {
+ __ flds(Address(ESP, temp_offset));
+ } else {
+ __ filds(Address(ESP, temp_offset));
+ }
} else {
Location stack_temp = Location::DoubleStackSlot(temp_offset);
codegen_->Move64(stack_temp, source);
- __ fldl(Address(ESP, temp_offset));
+ if (is_fp) {
+ __ fldl(Address(ESP, temp_offset));
+ } else {
+ __ fildl(Address(ESP, temp_offset));
+ }
}
}
}
@@ -2239,8 +2250,9 @@
__ subl(ESP, Immediate(2 * elem_size));
// Load the values to the FP stack in reverse order, using temporaries if needed.
- PushOntoFPStack(second, elem_size, 2 * elem_size, is_float);
- PushOntoFPStack(first, 0, 2 * elem_size, is_float);
+ const bool is_wide = !is_float;
+ PushOntoFPStack(second, elem_size, 2 * elem_size, /* is_fp */ true, is_wide);
+ PushOntoFPStack(first, 0, 2 * elem_size, /* is_fp */ true, is_wide);
// Loop doing FPREM until we stabilize.
Label retry;
diff --git a/compiler/optimizing/code_generator_x86.h b/compiler/optimizing/code_generator_x86.h
index 0cc3c65..1cb9e32 100644
--- a/compiler/optimizing/code_generator_x86.h
+++ b/compiler/optimizing/code_generator_x86.h
@@ -171,8 +171,10 @@
void GenerateMemoryBarrier(MemBarrierKind kind);
void HandleFieldSet(HInstruction* instruction, const FieldInfo& field_info);
void HandleFieldGet(HInstruction* instruction, const FieldInfo& field_info);
+ // Push value to FPU stack. `is_fp` specifies whether the value is floating point or not.
+ // `is_wide` specifies whether it is long/double or not.
void PushOntoFPStack(Location source, uint32_t temp_offset,
- uint32_t stack_adjustment, bool is_float);
+ uint32_t stack_adjustment, bool is_fp, bool is_wide);
void GenerateImplicitNullCheck(HNullCheck* instruction);
void GenerateExplicitNullCheck(HNullCheck* instruction);
diff --git a/compiler/utils/x86/assembler_x86.cc b/compiler/utils/x86/assembler_x86.cc
index 4cca529..7b206a3 100644
--- a/compiler/utils/x86/assembler_x86.cc
+++ b/compiler/utils/x86/assembler_x86.cc
@@ -883,6 +883,13 @@
}
+void X86Assembler::filds(const Address& src) {
+ AssemblerBuffer::EnsureCapacity ensured(&buffer_);
+ EmitUint8(0xDB);
+ EmitOperand(0, src);
+}
+
+
void X86Assembler::fincstp() {
AssemblerBuffer::EnsureCapacity ensured(&buffer_);
EmitUint8(0xD9);
diff --git a/compiler/utils/x86/assembler_x86.h b/compiler/utils/x86/assembler_x86.h
index f3675ae..a933474 100644
--- a/compiler/utils/x86/assembler_x86.h
+++ b/compiler/utils/x86/assembler_x86.h
@@ -349,6 +349,7 @@
void fistpl(const Address& dst);
void fistps(const Address& dst);
void fildl(const Address& src);
+ void filds(const Address& src);
void fincstp();
void ffree(const Immediate& index);
diff --git a/compiler/utils/x86_64/assembler_x86_64.cc b/compiler/utils/x86_64/assembler_x86_64.cc
index 2e0d9e1..699b0b2 100644
--- a/compiler/utils/x86_64/assembler_x86_64.cc
+++ b/compiler/utils/x86_64/assembler_x86_64.cc
@@ -984,6 +984,13 @@
}
+void X86_64Assembler::filds(const Address& src) {
+ AssemblerBuffer::EnsureCapacity ensured(&buffer_);
+ EmitUint8(0xDB);
+ EmitOperand(0, src);
+}
+
+
void X86_64Assembler::fincstp() {
AssemblerBuffer::EnsureCapacity ensured(&buffer_);
EmitUint8(0xD9);
diff --git a/compiler/utils/x86_64/assembler_x86_64.h b/compiler/utils/x86_64/assembler_x86_64.h
index a786a6c..3df0950 100644
--- a/compiler/utils/x86_64/assembler_x86_64.h
+++ b/compiler/utils/x86_64/assembler_x86_64.h
@@ -389,6 +389,7 @@
void fistpl(const Address& dst);
void fistps(const Address& dst);
void fildl(const Address& src);
+ void filds(const Address& src);
void fincstp();
void ffree(const Immediate& index);
diff --git a/test/422-type-conversion/src/Main.java b/test/422-type-conversion/src/Main.java
index 7ce2868..da5bd76 100644
--- a/test/422-type-conversion/src/Main.java
+++ b/test/422-type-conversion/src/Main.java
@@ -321,6 +321,7 @@
assertFloatEquals(9223372036854775807F, $opt$LongToFloat(9223372036854775807L)); // 2^63 - 1
assertFloatEquals(-9223372036854775807F, $opt$LongToFloat(-9223372036854775807L)); // -(2^63 - 1)
assertFloatEquals(-9223372036854775808F, $opt$LongToFloat(-9223372036854775808L)); // -(2^63)
+ assertFloatEquals(Float.intBitsToFloat(-555858671), $opt$LongToFloat(-8008112895877447681L));
}
private static void longToDouble() {