Commit 8732a586 authored by Lars T Hansen's avatar Lars T Hansen
Browse files

Bug 1669179 - Clean up predicate for unaligned FP accesses. r=nbp 

Several interlinked changes here:

- the predicate SupportsFastUnalignedAccesses is renamed as SupportsFastUnalignedFPAccesses,
  as this is the sense that is needed - we already assume that unaligned integer accesses
  are supported.
- DataView accessors that use this predicate are rewritten to test that the access type
  is an FP access before using this predicate
- In Wasm, the uses of this predicate only pertain to when FP accesses are used to
  implement inlined/unrolled memory.copy and memory.fill, so move the predicate so
  that it guards this case only, not all cases.

Differential Revision: https://phabricator.services.mozilla.com/D123356
parent 30e0a7da

js/public/ScalarType.h

+23 −0
Original line number Diff line number Diff line
@@ -125,6 +125,29 @@ static inline bool isBigIntType(Type atype) { 
  MOZ_CRASH("invalid scalar type");

}



static inline bool isFloatingType(Type atype) {

  switch (atype) {

    case Int8:

    case Uint8:

    case Uint8Clamped:

    case Int16:

    case Uint16:

    case Int32:

    case Uint32:

    case Int64:

    case BigInt64:

    case BigUint64:

      return false;

    case Float32:

    case Float64:

    case Simd128:

      return true;

    case MaxTypedArrayViewType:

      break;

  }

  MOZ_CRASH("invalid scalar type");

}



static inline const char* name(Type atype) {

  switch (atype) {

    case Int8:

js/src/jit/CodeGenerator.cpp

+7 −4
Original line number Diff line number Diff line
@@ -12696,8 +12696,9 @@ void CodeGenerator::visitLoadDataViewElement(LLoadDataViewElement* lir) { 
                ToBoolean(littleEndian) == MOZ_LITTLE_ENDIAN();









  // Directly load if no byte swap is needed and the platform supports unaligned









  // accesses for floating point registers.









  if (noSwap && MacroAssembler::SupportsFastUnalignedAccesses()) {









  // accesses for the access.  (Such support is assumed for integer types.)









  if (noSwap && (!Scalar::isFloatingType(storageType) ||









                 MacroAssembler::SupportsFastUnalignedFPAccesses())) {









    if (!Scalar::isBigIntType(storageType)) {









      Label fail;









      masm.loadFromTypedArray(storageType, source, out, temp, &fail);








@@ -13077,8 +13078,10 @@ void CodeGenerator::visitStoreDataViewElement(LStoreDataViewElement* lir) {







                ToBoolean(littleEndian) == MOZ_LITTLE_ENDIAN();

















  // Directly store if no byte swap is needed and the platform supports









  // unaligned accesses for floating point registers.









  if (noSwap && MacroAssembler::SupportsFastUnalignedAccesses()) {









  // unaligned accesses for the access.  (Such support is assumed for integer









  // types.)









  if (noSwap && (!Scalar::isFloatingType(writeType) ||









                 MacroAssembler::SupportsFastUnalignedFPAccesses())) {









    if (!Scalar::isBigIntType(writeType)) {









      StoreToTypedArray(masm, writeType, value, dest);









    } else {
































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



+4
−1






























Original line number
Diff line number
Diff line







@@ -1686,7 +1686,10 @@ class Assembler : public AssemblerShared {

















  static bool SupportsFloatingPoint() { return HasVFP(); }









  static bool SupportsUnalignedAccesses() { return HasARMv7(); }









  static bool SupportsFastUnalignedAccesses() { return false; }









  // Note, returning false here is technically wrong, but one has to go via the









  // as_vldr_unaligned and as_vstr_unaligned instructions to get proper behavior









  // and those are NEON-specific and have to be asked for specifically.









  static bool SupportsFastUnalignedFPAccesses() { return false; }



















  static bool HasRoundInstruction(RoundingMode mode) { return false; }










































js/src/jit/arm64/Assembler-arm64.h



+1
−1






























Original line number
Diff line number
Diff line







@@ -537,7 +537,7 @@ class Assembler : public vixl::Assembler {

















  static bool SupportsFloatingPoint() { return true; }









  static bool SupportsUnalignedAccesses() { return true; }









  static bool SupportsFastUnalignedAccesses() { return true; }









  static bool SupportsFastUnalignedFPAccesses() { return true; }









  static bool SupportsWasmSimd() { return true; }



















  static bool HasRoundInstruction(RoundingMode mode) {
































js/src/jit/mips-shared/Assembler-mips-shared.h



+1
−1






























Original line number
Diff line number
Diff line







@@ -1229,7 +1229,7 @@ class AssemblerMIPSShared : public AssemblerShared {







#endif









  }









  static bool SupportsUnalignedAccesses() { return true; }









  static bool SupportsFastUnalignedAccesses() { return false; }









  static bool SupportsFastUnalignedFPAccesses() { return false; }



















  static bool HasRoundInstruction(RoundingMode mode) { return false; }