Bug 1289054 - Part 18: Implement the 64bit variant of WasmTruncate on arm, r=bbouvier

js/src/asmjs/WasmTypes.cpp

@@ -200,6 +200,30 @@ UModI64(uint32_t x_hi, uint32_t x_lo, uint32_t y_hi, uint32_t y_lo)
     return x % y;
 }
 
+static int64_t
+TruncateDoubleToInt64(double input)
+{
+    // Note: INT64_MAX is not representable in double. It is actually INT64_MAX + 1.
+    // Therefore also sending the failure value.
+    if (input >= double(INT64_MAX))
+        return 0x8000000000000000;
+    if (input < double(INT64_MIN))
+        return 0x8000000000000000;
+    return int64_t(input);
+}
+
+static uint64_t
+TruncateDoubleToUint64(double input)
+{
+    // Note: UINT64_MAX is not representable in double. It is actually UINT64_MAX + 1.
+    // Therefore also sending the failure value.
+    if (input >= double(UINT64_MAX))
+        return 0x8000000000000000;
+    if (input <= -1.0)
+        return 0x8000000000000000;
+    return uint64_t(input);
+}
+
 template <class F>
 static inline void*
 FuncCast(F* pf, ABIFunctionType type)
@@ -247,6 +271,10 @@ wasm::AddressOf(SymbolicAddress imm, ExclusiveContext* cx)
         return FuncCast(ModI64, Args_General4);
       case SymbolicAddress::UModI64:
         return FuncCast(UModI64, Args_General4);
+      case SymbolicAddress::TruncateDoubleToUint64:
+        return FuncCast(TruncateDoubleToUint64, Args_Int64_Double);
+      case SymbolicAddress::TruncateDoubleToInt64:
+        return FuncCast(TruncateDoubleToInt64, Args_Int64_Double);
 #if defined(JS_CODEGEN_ARM)
       case SymbolicAddress::aeabi_idivmod:
         return FuncCast(__aeabi_idivmod, Args_General2);

js/src/asmjs/WasmTypes.h

@@ -901,6 +901,8 @@ enum class SymbolicAddress
     UDivI64,
     ModI64,
     UModI64,
+    TruncateDoubleToInt64,
+    TruncateDoubleToUint64,
     Limit
 };
 

js/src/jit/IonTypes.h

@@ -762,10 +762,11 @@ enum {
     ArgType_General = 0x1,
     ArgType_Double  = 0x2,
     ArgType_Float32 = 0x3,
+    ArgType_Int64 = 0x4,
 
     RetType_Shift   = 0x0,
-    ArgType_Shift   = 0x2,
-    ArgType_Mask    = 0x3
+    ArgType_Shift   = 0x3,
+    ArgType_Mask    = 0x7
 };
 
 enum ABIFunctionType
@@ -782,6 +783,9 @@ enum ABIFunctionType
     Args_General7 = Args_General6 | (ArgType_General << (ArgType_Shift * 7)),
     Args_General8 = Args_General7 | (ArgType_General << (ArgType_Shift * 8)),
 
+    // int64 f(double)
+    Args_Int64_Double = (ArgType_Int64 << RetType_Shift) | (ArgType_Double << ArgType_Shift),
+
     // double f()
     Args_Double_None = ArgType_Double << RetType_Shift,
 

js/src/jit/arm/CodeGenerator-arm.cpp

@@ -2968,6 +2968,45 @@ CodeGeneratorARM::visitWasmTruncateToInt32(LWasmTruncateToInt32* lir)
     masm.bind(ool->rejoin());
 }
 
+void
+CodeGeneratorARM::visitWasmTruncateToInt64(LWasmTruncateToInt64* lir)
+{
+    FloatRegister input = ToFloatRegister(lir->input());
+    FloatRegister inputDouble = input;
+    Register64 output = ToOutRegister64(lir);
+
+    MWasmTruncateToInt64* mir = lir->mir();
+    MIRType fromType = mir->input()->type();
+
+    auto* ool = new(alloc()) OutOfLineWasmTruncateCheck(mir, input);
+    addOutOfLineCode(ool, mir);
+
+    ScratchDoubleScope scratchScope(masm);
+    if (fromType == MIRType::Float32) {
+        inputDouble = ScratchDoubleReg;
+        masm.convertFloat32ToDouble(input, inputDouble);
+    }
+
+    masm.Push(input);
+
+    masm.setupUnalignedABICall(output.high);
+    masm.passABIArg(inputDouble, MoveOp::DOUBLE);
+    if (lir->mir()->isUnsigned())
+        masm.callWithABI(wasm::SymbolicAddress::TruncateDoubleToUint64);
+    else
+        masm.callWithABI(wasm::SymbolicAddress::TruncateDoubleToInt64);
+
+    masm.Pop(input);
+
+    masm.ma_cmp(output.high, Imm32(0x80000000));
+    masm.ma_cmp(output.low, Imm32(0x00000000), Assembler::Equal);
+    masm.ma_b(ool->entry(), Assembler::Equal);
+
+    masm.bind(ool->rejoin());
+
+    MOZ_ASSERT(ReturnReg64 == output);
+}
+
 void
 CodeGeneratorARM::visitOutOfLineWasmTruncateCheck(OutOfLineWasmTruncateCheck* ool)
 {
@@ -2989,39 +3028,57 @@ CodeGeneratorARM::visitOutOfLineWasmTruncateCheck(OutOfLineWasmTruncateCheck* oo
     // Handle special values.
     Label fail;
 
+    // By default test for the following inputs and bail:
+    // signed:   ] -Inf, INTXX_MIN - 1.0 ] and [ INTXX_MAX + 1.0 : +Inf [
+    // unsigned: ] -Inf, -1.0 ] and [ UINTXX_MAX + 1.0 : +Inf [
+    // Note: we cannot always represent those exact values. As a result
+    // this changes the actual comparison a bit.
     double minValue, maxValue;
-    if (ool->isUnsigned()) {
-        minValue = -1;
-        maxValue = double(UINT32_MAX) + 1.0;
+    Assembler::DoubleCondition minCond = Assembler::DoubleLessThanOrEqual;
+    Assembler::DoubleCondition maxCond = Assembler::DoubleGreaterThanOrEqual;
+    if (ool->toType() == MIRType::Int64) {
+        if (ool->isUnsigned()) {
+            minValue = -1;
+            maxValue = double(UINT64_MAX) + 1.0;
+        } else {
+            // In the float32/double range there exists no value between
+            // INT64_MIN and INT64_MIN - 1.0. Making INT64_MIN the lower-bound.
+            minValue = double(INT64_MIN);
+            minCond = Assembler::DoubleLessThan;
+            maxValue = double(INT64_MAX) + 1.0;
+        }
     } else {
-        minValue = double(INT32_MIN) - 1.0;
-        maxValue = double(INT32_MAX) + 1.0;
+        if (ool->isUnsigned()) {
+            minValue = -1;
+            maxValue = double(UINT32_MAX) + 1.0;
+        } else {
+            if (fromType == MIRType::Float32) {
+                // In the float32 range there exists no value between
+                // INT32_MIN and INT32_MIN - 1.0. Making INT32_MIN the lower-bound.
+                minValue = double(INT32_MIN);
+                minCond = Assembler::DoubleLessThan;
+            } else {
+                minValue = double(INT32_MIN) - 1.0;
+            }
+            maxValue = double(INT32_MAX) + 1.0;
+        }
     }
 
     if (fromType == MIRType::Double) {
         scratch = scratchScope.doubleOverlay();
         masm.loadConstantDouble(minValue, scratch);
-        masm.branchDouble(Assembler::DoubleLessThanOrEqual, input, scratch, &fail);
+        masm.branchDouble(minCond, input, scratch, &fail);
 
         masm.loadConstantDouble(maxValue, scratch);
-        masm.branchDouble(Assembler::DoubleGreaterThanOrEqual, input, scratch, &fail);
+        masm.branchDouble(maxCond, input, scratch, &fail);
     } else {
         MOZ_ASSERT(fromType == MIRType::Float32);
         scratch = scratchScope.singleOverlay();
-
-        // For int32, float(minValue) rounds to INT32_MIN, we want to fail when
-        // input < float(minValue).
-        // For uint32, float(minValue) == -1, we want to fail when input <= -1.
-        auto condition = minValue == -1.0
-                         ? Assembler::DoubleLessThanOrEqual
-                         : Assembler::DoubleLessThan;
-
         masm.loadConstantFloat32(float(minValue), scratch);
-        masm.branchFloat(condition, input, scratch, &fail);
+        masm.branchFloat(minCond, input, scratch, &fail);
 
-        // maxValue is exactly represented in both cases.
         masm.loadConstantFloat32(float(maxValue), scratch);
-        masm.branchFloat(Assembler::DoubleGreaterThanOrEqual, input, scratch, &fail);
+        masm.branchFloat(maxCond, input, scratch, &fail);
     }
 
     // We had an actual correct value, get back to where we were.

js/src/jit/arm/CodeGenerator-arm.h

@@ -177,6 +177,7 @@ class CodeGeneratorARM : public CodeGeneratorShared
     virtual void visitClzI64(LClzI64* ins);
     virtual void visitCtzI64(LCtzI64* ins);
     virtual void visitNotI64(LNotI64* ins);
+    virtual void visitWasmTruncateToInt64(LWasmTruncateToInt64* ins);
 
     // Out of line visitors.
     void visitOutOfLineBailout(OutOfLineBailout* ool);

js/src/jit/arm/LIR-arm.h

@@ -541,6 +541,21 @@ class LAsmJSAtomicBinopCallout : public LCallInstructionHelper<1, 2, 0>
     }
 };
 
+class LWasmTruncateToInt64 : public LCallInstructionHelper<INT64_PIECES, 1, 0>
+{
+  public:
+    LIR_HEADER(WasmTruncateToInt64);
+
+    LWasmTruncateToInt64(const LAllocation& in)
+    {
+        setOperand(0, in);
+    }
+
+    MWasmTruncateToInt64* mir() const {
+        return mir_->toWasmTruncateToInt64();
+    }
+};
+
 } // namespace jit
 } // namespace js
 

js/src/jit/arm/LOpcodes-arm.h

@@ -21,6 +21,7 @@
     _(AsmJSAtomicExchangeCallout) \
     _(AsmJSAtomicBinopCallout)  \
     _(DivOrModI64)              \
-    _(UDivOrModI64)
+    _(UDivOrModI64)             \
+    _(WasmTruncateToInt64)
 
 #endif /* jit_arm_LOpcodes_arm_h */

js/src/jit/arm/Lowering-arm.cpp

@@ -915,7 +915,10 @@ LIRGeneratorARM::visitRandom(MRandom* ins)
 void
 LIRGeneratorARM::visitWasmTruncateToInt64(MWasmTruncateToInt64* ins)
 {
-    MOZ_CRASH("NY");
+    MDefinition* opd = ins->input();
+    MOZ_ASSERT(opd->type() == MIRType::Double || opd->type() == MIRType::Float32);
+
+    defineReturn(new(alloc()) LWasmTruncateToInt64(useRegisterAtStart(opd)), ins);
 }
 
 void

js/src/jit/arm/Simulator-arm.cpp

@@ -2287,6 +2287,7 @@ typedef double (*Prototype_Double_None)();
 typedef double (*Prototype_Double_Double)(double arg0);
 typedef double (*Prototype_Double_Int)(int32_t arg0);
 typedef int32_t (*Prototype_Int_Double)(double arg0);
+typedef int64_t (*Prototype_Int64_Double)(double arg0);
 typedef int32_t (*Prototype_Int_DoubleIntInt)(double arg0, int32_t arg1, int32_t arg2);
 typedef int32_t (*Prototype_Int_IntDoubleIntInt)(int32_t arg0, double arg1, int32_t arg2,
                                                  int32_t arg3);
@@ -2429,6 +2430,16 @@ Simulator::softwareInterrupt(SimInstruction* instr)
             setCallResult(result);
             break;
           }
+          case Args_Int64_Double: {
+            double dval0, dval1;
+            int32_t ival;
+            getFpArgs(&dval0, &dval1, &ival);
+            Prototype_Int64_Double target = reinterpret_cast<Prototype_Int64_Double>(external);
+            int64_t result = target(dval0);
+            scratchVolatileRegisters(/* scratchFloat = true */);
+            setCallResult(result);
+            break;
+          }
           case Args_Double_None: {
             Prototype_Double_None target = reinterpret_cast<Prototype_Double_None>(external);
             double dresult = target();