[RISC-V][LoongArch64] Handle reversed fields in lowered structs #115933
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
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@@ -2716,8 +2716,8 @@ static void SetFpStructInRegistersInfoField(FpStructInRegistersInfo& info, int i | |
| (index == 0 ? info.offset1st : info.offset2nd) = offset; | ||
| } | ||
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| static bool HandleInlineArray(int elementTypeIndex, int nElements, | ||
| FpStructInRegistersInfo& info, int& typeIndex, uint32_t& occupiedBytesMap DEBUG_ARG(int nestingLevel)) | ||
| { | ||
| int nFlattenedFieldsPerElement = typeIndex - elementTypeIndex; | ||
| if (nFlattenedFieldsPerElement == 0) | ||
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@@ -2759,45 +2759,65 @@ static bool HandleInlineArray(int elementTypeIndex, int nElements, FpStructInReg | |
| int sizeShiftMask = (info.flags & FpStruct::SizeShift1stMask) << 2; | ||
| info.flags = FpStruct::Flags(info.flags | floatFlag | sizeShiftMask); // merge with 1st field | ||
| info.offset2nd = info.offset1st + info.Size1st(); // bump up the field offset | ||
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| assert(info.Size1st() == info.Size2nd()); | ||
| uint32_t startOffset = info.offset2nd; | ||
| uint32_t endOffset = startOffset + info.Size2nd(); | ||
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| uint32_t fieldOccupation = (~0u << startOffset) ^ (~0u << endOffset); | ||
| if ((occupiedBytesMap & fieldOccupation) != 0) | ||
| { | ||
| LOG((LF_JIT, LL_EVERYTHING, "FpStructInRegistersInfo:%*s " | ||
| " * duplicated array element [%i..%i) overlaps with other fields (occupied bytes map: 0x%04x), treat as union\n", | ||
| nestingLevel * 4, "", startOffset, endOffset, occupiedBytesMap)); | ||
| return false; | ||
| } | ||
| occupiedBytesMap |= fieldOccupation; | ||
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| LOG((LF_JIT, LL_EVERYTHING, "FpStructInRegistersInfo:%*s * duplicated array element type\n", | ||
| nestingLevel * 4, "")); | ||
| } | ||
| return true; | ||
| } | ||
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| static bool FlattenFields(TypeHandle th, uint32_t structOffset, FpStructInRegistersInfo& info, int& typeIndex | ||
| DEBUG_ARG(int nestingLevel)) | ||
| { | ||
| bool isManaged = !th.IsTypeDesc(); | ||
| MethodTable* pMT = isManaged ? th.AsMethodTable() : th.AsNativeValueType(); | ||
| int nFields = isManaged ? pMT->GetNumIntroducedInstanceFields() : pMT->GetNativeLayoutInfo()->GetNumFields(); | ||
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| LOG((LF_JIT, LL_EVERYTHING, "FpStructInRegistersInfo:%*s flattening %s (%s, %i fields) at offset %u\n", | ||
| nestingLevel * 4, "", pMT->GetDebugClassName(), (isManaged ? "managed" : "native"), nFields, structOffset)); | ||
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| // TODO: templatize isManaged and use if constexpr for differences when we migrate to C++17 | ||
| // because the logic for both branches is nearly the same. | ||
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| uint32_t occupiedBytesMap = 0; | ||
| if (isManaged) | ||
| { | ||
| FieldDesc* fields = pMT->GetApproxFieldDescListRaw(); | ||
| int elementTypeIndex = typeIndex; | ||
| for (int i = 0; i < nFields; ++i) | ||
| { | ||
| uint32_t startOffset = structOffset + fields[i].GetOffset(); | ||
| uint32_t endOffset = startOffset + fields[i].GetSize(); | ||
|
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| uint32_t fieldOccupation = (~0u << startOffset) ^ (~0u << endOffset); | ||
| if ((occupiedBytesMap & fieldOccupation) != 0) | ||
| { | ||
| LOG((LF_JIT, LL_EVERYTHING, "FpStructInRegistersInfo:%*s " | ||
| " * field %s [%i..%i) overlaps with other fields (occupied bytes map: 0x%04x), treat as union\n", | ||
| nestingLevel * 4, "", fields[i].GetDebugName(), startOffset, endOffset, occupiedBytesMap)); | ||
| return false; | ||
| } | ||
| occupiedBytesMap |= fieldOccupation; | ||
|
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||
| CorElementType type = fields[i].GetFieldType(); | ||
| if (type == ELEMENT_TYPE_VALUETYPE) | ||
| { | ||
| MethodTable* nested = fields[i].GetApproxFieldTypeHandleThrowing().GetMethodTable(); | ||
| if (!FlattenFields(TypeHandle(nested), startOffset, info, typeIndex DEBUG_ARG(nestingLevel + 1))) | ||
| return false; | ||
| } | ||
| else if (fields[i].GetSize() <= TARGET_POINTER_SIZE) | ||
|
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@@ -2810,12 +2830,10 @@ static bool FlattenFields(TypeHandle th, uint32_t offset, FpStructInRegistersInf | |
| } | ||
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| bool isFloating = CorTypeInfo::IsFloat_NoThrow(type); | ||
| SetFpStructInRegistersInfoField(info, typeIndex++, isFloating, CorTypeInfo::Size_NoThrow(type), startOffset); | ||
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| LOG((LF_JIT, LL_EVERYTHING, "FpStructInRegistersInfo:%*s * found field %s [%i..%i), type: %s\n", | ||
| nestingLevel * 4, "", fields[i].GetDebugName(), startOffset, endOffset, CorTypeInfo::GetName(type))); | ||
| } | ||
| else | ||
| { | ||
|
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@@ -2842,7 +2860,7 @@ static bool FlattenFields(TypeHandle th, uint32_t offset, FpStructInRegistersInf | |
| return false; | ||
| } | ||
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| if (!HandleInlineArray(elementTypeIndex, nElements, info, typeIndex, occupiedBytesMap DEBUG_ARG(nestingLevel + 1))) | ||
| return false; | ||
| } | ||
| } | ||
|
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@@ -2851,15 +2869,18 @@ static bool FlattenFields(TypeHandle th, uint32_t offset, FpStructInRegistersInf | |
| const NativeFieldDescriptor* fields = pMT->GetNativeLayoutInfo()->GetNativeFieldDescriptors(); | ||
| for (int i = 0; i < nFields; ++i) | ||
| { | ||
| uint32_t startOffset = structOffset + fields[i].GetExternalOffset(); | ||
| uint32_t endOffset = startOffset + fields[i].NativeSize(); | ||
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| uint32_t fieldOccupation = (~0u << startOffset) ^ (~0u << endOffset); | ||
| if ((occupiedBytesMap & fieldOccupation) != 0) | ||
| { | ||
| LOG((LF_JIT, LL_EVERYTHING, "FpStructInRegistersInfo:%*s " | ||
| " * field %s [%i..%i) overlaps with other fields (occupied bytes map: 0x%04x), treat as union\n", | ||
| nestingLevel * 4, "", fields[i].GetFieldDesc()->GetDebugName(), startOffset, endOffset)); | ||
| return false; | ||
| } | ||
| occupiedBytesMap |= fieldOccupation; | ||
|
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| static const char* categoryNames[] = {"FLOAT", "NESTED", "INTEGER", "ILLEGAL"}; | ||
| NativeFieldCategory category = fields[i].GetCategory(); | ||
|
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@@ -2868,12 +2889,12 @@ static bool FlattenFields(TypeHandle th, uint32_t offset, FpStructInRegistersInf | |
| int elementTypeIndex = typeIndex; | ||
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| MethodTable* nested = fields[i].GetNestedNativeMethodTable(); | ||
| if (!FlattenFields(TypeHandle(nested), startOffset, info, typeIndex DEBUG_ARG(nestingLevel + 1))) | ||
| return false; | ||
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| // In native layout fixed arrays are marked as NESTED just like structs | ||
| int nElements = fields[i].GetNumElements(); | ||
| if (!HandleInlineArray(elementTypeIndex, nElements, info, typeIndex, occupiedBytesMap DEBUG_ARG(nestingLevel + 1))) | ||
| return false; | ||
| } | ||
| else if (fields[i].NativeSize() <= TARGET_POINTER_SIZE) | ||
|
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@@ -2886,13 +2907,10 @@ static bool FlattenFields(TypeHandle th, uint32_t offset, FpStructInRegistersInf | |
| } | ||
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| bool isFloating = (category == NativeFieldCategory::FLOAT); | ||
| SetFpStructInRegistersInfoField(info, typeIndex++, isFloating, fields[i].NativeSize(), startOffset); | ||
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| LOG((LF_JIT, LL_EVERYTHING, "FpStructInRegistersInfo:%*s * found field %s [%i..%i), type: %s\n", | ||
| nestingLevel * 4, "", fields[i].GetFieldDesc()->GetDebugName(), startOffset, endOffset, categoryNames[(int)category])); | ||
| } | ||
| else | ||
| { | ||
|
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@@ -2930,6 +2948,21 @@ FpStructInRegistersInfo MethodTable::GetFpStructInRegistersInfo(TypeHandle th) | |
| } | ||
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| assert(nFields == 1 || nFields == 2); | ||
| if (nFields == 2 && info.offset1st > info.offset2nd) | ||
| { | ||
| LOG((LF_JIT, LL_EVERYTHING, "FpStructInRegistersInfo: struct %s (%u bytes): swap fields to match memory order\n", | ||
| (!th.IsTypeDesc() ? th.AsMethodTable() : th.AsNativeValueType())->GetDebugClassName(), th.GetSize())); | ||
| info.flags = FpStruct::Flags( | ||
| ((info.flags & FloatInt) << (PosIntFloat - PosFloatInt)) | | ||
| ((info.flags & IntFloat) >> (PosIntFloat - PosFloatInt)) | | ||
| ((info.flags & SizeShift1stMask) << (PosSizeShift2nd - PosSizeShift1st)) | | ||
| ((info.flags & SizeShift2ndMask) >> (PosSizeShift2nd - PosSizeShift1st)) | ||
| ); | ||
| std::swap(info.offset1st, info.offset2nd); | ||
| } | ||
|
Comment on lines
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+2962
There was a problem hiding this comment. The order matters for two floats and the calling convention wasn't clear. The only precedent I could find was GCC/gnat compiling Ada of all places, I made a proposal following it: riscv-non-isa/riscv-elf-psabi-doc#463, LoongArch gnat also behaves this way. For int-float structs it doesn't matter but I'm ordering the fields as they come in memory anyway for consistency. |
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| assert((info.flags & (OnlyOne | BothFloat)) == 0); | ||
| assert((info.flags & FloatInt) == 0 || info.Size1st() == sizeof(float) || info.Size1st() == sizeof(double)); | ||
| assert((info.flags & IntFloat) == 0 || info.Size2nd() == sizeof(float) || info.Size2nd() == sizeof(double)); | ||
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| if ((info.flags & (FloatInt | IntFloat)) == (FloatInt | IntFloat)) | ||
| { | ||
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Is
nFields == 2the only case that needs to be handled? What about e.g. 8 byte fields and a double field? Can that combination not be passed in an integer + float register?Uh oh!
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Yes
Only structs with one or two primitive fields (at least one of them FP) are lowered, structs with more fields are passed in integer registers and/or on the stack as they are laid out in memory.
https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/87aecf601722171c570120a46003be3c17ad3108/riscv-cc.adoc?plain=1#L316-L336