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Merged
jakobbotsch merged 3 commits into from
Feb 16, 2026
Merged

JIT: Remove dataSection flexible array #124373

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5e5cf99
JIT: Remove `dataSection` flexible array
jakobbotsch Feb 13, 2026
54d61a7
Missed reference
jakobbotsch Feb 13, 2026
ba10672
Encapsulate union accesses
jakobbotsch Feb 13, 2026
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2 changes: 1 addition & 1 deletion src/coreclr/jit/codegencommon.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -6831,7 +6831,7 @@ void CodeGen::genReportAsyncDebugInfo()
uint32_t diagNativeOffset = 0;
if (genAsyncResumeInfoTable != nullptr)
{
emitLocation& emitLoc = ((emitLocation*)genAsyncResumeInfoTable->dsCont)[i];
emitLocation& emitLoc = genAsyncResumeInfoTable->Locations()[i];
if (emitLoc.Valid())
{
diagNativeOffset = emitLoc.CodeOffset(GetEmitter());
Expand Down
2 changes: 1 addition & 1 deletion src/coreclr/jit/codegenlinear.cpp
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Expand Up @@ -961,7 +961,7 @@ void CodeGen::genRecordAsyncResume(GenTreeVal* asyncResume)
emitter::dataSection* asyncResumeInfo;
genEmitAsyncResumeInfoTable(&asyncResumeInfo);

((emitLocation*)asyncResumeInfo->dsCont)[index] = emitLocation(GetEmitter());
asyncResumeInfo->Locations()[index] = emitLocation(GetEmitter());
}

/*
Expand Down
67 changes: 34 additions & 33 deletions src/coreclr/jit/emit.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -7811,14 +7811,14 @@ UNATIVE_OFFSET emitter::emitDataGenBeg(unsigned size, unsigned alignment, var_ty

/* Allocate a data section descriptor and add it to the list */

dataSection* secDesc = emitDataSecCur = (dataSection*)emitGetMem(roundUp(sizeof(*secDesc) + size));
dataSection* secDesc = emitDataSecCur = (dataSection*)emitGetMem(sizeof(*secDesc));
secDesc->dsType = dataSection::data;
secDesc->Data() = (BYTE*)emitGetMem(size);

secDesc->dsSize = size;

secDesc->dsAlignment = alignment;

secDesc->dsType = dataSection::data;

secDesc->dsDataType = dataType;

secDesc->dsNext = nullptr;
Expand Down Expand Up @@ -7864,14 +7864,14 @@ UNATIVE_OFFSET emitter::emitBBTableDataGenBeg(unsigned numEntries, bool relative

/* Allocate a data section descriptor and add it to the list */

secDesc = emitDataSecCur = (dataSection*)emitGetMem(roundUp(sizeof(*secDesc) + numEntries * sizeof(BasicBlock*)));
secDesc = emitDataSecCur = (dataSection*)emitGetMem(sizeof(*secDesc));
secDesc->dsType = relativeAddr ? dataSection::blockRelative32 : dataSection::blockAbsoluteAddr;
secDesc->Blocks() = (BasicBlock**)emitGetMem(numEntries * sizeof(BasicBlock*));

secDesc->dsSize = emittedSize;

secDesc->dsAlignment = elemSize;

secDesc->dsType = relativeAddr ? dataSection::blockRelative32 : dataSection::blockAbsoluteAddr;

secDesc->dsDataType = TYP_UNKNOWN;

secDesc->dsNext = nullptr;
Expand Down Expand Up @@ -7905,14 +7905,15 @@ void emitter::emitAsyncResumeTable(unsigned numEntries, UNATIVE_OFFSET* dataSecO
unsigned emittedSize = sizeof(CORINFO_AsyncResumeInfo) * numEntries;
emitConsDsc.dsdOffs += emittedSize;

dataSection* secDesc = (dataSection*)emitGetMem(roundUp(sizeof(dataSection) + numEntries * sizeof(emitLocation)));
dataSection* secDesc = (dataSection*)emitGetMem(sizeof(dataSection));
secDesc->dsType = dataSection::asyncResumeInfo;
secDesc->Locations() = (emitLocation*)emitGetMem(numEntries * sizeof(emitLocation));

for (unsigned i = 0; i < numEntries; i++)
new (secDesc->dsCont + i * sizeof(emitLocation), jitstd::placement_t()) emitLocation();
new (&secDesc->Locations()[i], jitstd::placement_t()) emitLocation();

secDesc->dsSize = emittedSize;
secDesc->dsAlignment = TARGET_POINTER_SIZE;
secDesc->dsType = dataSection::asyncResumeInfo;
secDesc->dsDataType = TYP_UNKNOWN;
secDesc->dsNext = nullptr;

Expand Down Expand Up @@ -7949,7 +7950,7 @@ void emitter::emitDataGenData(unsigned offs, const void* data, UNATIVE_OFFSET si

assert(emitDataSecCur->dsType == dataSection::data);

memcpy(emitDataSecCur->dsCont + offs, data, size);
memcpy(emitDataSecCur->Data() + offs, data, size);
}

/*****************************************************************************
Expand All @@ -7967,7 +7968,7 @@ void emitter::emitDataGenData(unsigned index, BasicBlock* label)

assert(emitDataSecCur->dsSize >= emittedElemSize * (index + 1));

((BasicBlock**)(emitDataSecCur->dsCont))[index] = label;
emitDataSecCur->Blocks()[index] = label;
}

/*****************************************************************************
Expand Down Expand Up @@ -8011,7 +8012,7 @@ UNATIVE_OFFSET emitter::emitDataGenFind(const void* cnsAddr, unsigned cnsSize, u
//
if ((secDesc->dsType == dataSection::data) && (secDesc->dsSize >= cnsSize) && ((curOffs % alignment) == 0))
{
if (memcmp(cnsAddr, secDesc->dsCont, cnsSize) == 0)
if (memcmp(cnsAddr, secDesc->Data(), cnsSize) == 0)
{
cnum = curOffs;

Expand Down Expand Up @@ -8393,7 +8394,7 @@ void emitter::emitOutputDataSec(dataSecDsc* sec, AllocMemChunk* chunks)
target_size_t* bDstRW = (target_size_t*)dstRW;
for (unsigned i = 0; i < numElems; i++)
{
BasicBlock* block = ((BasicBlock**)dsc->dsCont)[i];
BasicBlock* block = dsc->Blocks()[i];

// Convert the BasicBlock* value to an IG address
insGroup* lab = (insGroup*)emitCodeGetCookie(block);
Expand Down Expand Up @@ -8424,7 +8425,7 @@ void emitter::emitOutputDataSec(dataSecDsc* sec, AllocMemChunk* chunks)

for (unsigned i = 0; i < numElems; i++)
{
BasicBlock* block = ((BasicBlock**)dsc->dsCont)[i];
BasicBlock* block = dsc->Blocks()[i];

// Convert the BasicBlock* value to an IG address
insGroup* lab = (insGroup*)emitCodeGetCookie(block);
Expand All @@ -8444,7 +8445,7 @@ void emitter::emitOutputDataSec(dataSecDsc* sec, AllocMemChunk* chunks)
CORINFO_AsyncResumeInfo* aDstRW = (CORINFO_AsyncResumeInfo*)dstRW;
for (size_t i = 0; i < numElems; i++)
{
emitLocation* emitLoc = &((emitLocation*)dsc->dsCont)[i];
emitLocation* emitLoc = &dsc->Locations()[i];

// Async call may have been removed very late, after we have introduced suspension/resumption.
// In those cases just encode null.
Expand All @@ -8468,7 +8469,7 @@ void emitter::emitOutputDataSec(dataSecDsc* sec, AllocMemChunk* chunks)
// Simple binary data: copy the bytes to the target
assert(dsc->dsType == dataSection::data);

memcpy(dstRW, dsc->dsCont, dscSize);
memcpy(dstRW, dsc->Data(), dscSize);

#ifdef DEBUG
if (EMITVERBOSE)
Expand All @@ -8477,7 +8478,7 @@ void emitter::emitOutputDataSec(dataSecDsc* sec, AllocMemChunk* chunks)

for (size_t i = 0; i < dscSize; i++)
{
printf("%02x ", dsc->dsCont[i]);
printf("%02x ", dsc->Data()[i]);
if ((((i + 1) % 16) == 0) && (i + 1 != dscSize))
{
printf("\n\t\t\t\t\t");
Expand All @@ -8487,10 +8488,10 @@ void emitter::emitOutputDataSec(dataSecDsc* sec, AllocMemChunk* chunks)
{
case TYP_FLOAT:
printf(" ; float %9.6g",
FloatingPointUtils::convertToDouble(*reinterpret_cast<float*>(&dsc->dsCont)));
FloatingPointUtils::convertToDouble(*reinterpret_cast<float*>(dsc->Data())));
break;
case TYP_DOUBLE:
printf(" ; double %12.9g", *reinterpret_cast<double*>(&dsc->dsCont));
printf(" ; double %12.9g", *reinterpret_cast<double*>(dsc->Data()));
break;
default:
break;
Expand Down Expand Up @@ -8551,7 +8552,7 @@ void emitter::emitDispDataSec(dataSecDsc* section, AllocMemChunk* dataChunks)
printf(labelFormat, "");
}

BasicBlock* block = reinterpret_cast<BasicBlock**>(data->dsCont)[i];
BasicBlock* block = data->Blocks()[i];
insGroup* ig = static_cast<insGroup*>(emitCodeGetCookie(block));

const char* blockLabel = emitLabelString(ig);
Expand Down Expand Up @@ -8617,7 +8618,7 @@ void emitter::emitDispDataSec(dataSecDsc* section, AllocMemChunk* dataChunks)
printf(labelFormat, label);
}

emitLocation* emitLoc = &((emitLocation*)data->dsCont)[i];
emitLocation* emitLoc = &data->Locations()[i];

printf("\tdq\t%s\n", resumeStubName);

Expand Down Expand Up @@ -8668,9 +8669,9 @@ void emitter::emitDispDataSec(dataSecDsc* section, AllocMemChunk* dataChunks)
{
printf("\t<Unexpected data size %d (expected >= 4)\n", data->dsSize);
}
printf("\tdd\t%08llXh\t", (UINT64) * reinterpret_cast<uint32_t*>(&data->dsCont[i]));
printf("\tdd\t%08llXh\t", (UINT64) * reinterpret_cast<uint32_t*>(&data->Data()[i]));
printf("\t; %9.6g",
FloatingPointUtils::convertToDouble(*reinterpret_cast<float*>(&data->dsCont[i])));
FloatingPointUtils::convertToDouble(*reinterpret_cast<float*>(&data->Data()[i])));
i += 4;
break;

Expand All @@ -8679,21 +8680,21 @@ void emitter::emitDispDataSec(dataSecDsc* section, AllocMemChunk* dataChunks)
{
printf("\t<Unexpected data size %d (expected >= 8)\n", data->dsSize);
}
printf("\tdq\t%016llXh", *reinterpret_cast<uint64_t*>(&data->dsCont[i]));
printf("\t; %12.9g", *reinterpret_cast<double*>(&data->dsCont[i]));
printf("\tdq\t%016llXh", *reinterpret_cast<uint64_t*>(&data->Data()[i]));
printf("\t; %12.9g", *reinterpret_cast<double*>(&data->Data()[i]));
i += 8;
break;

default:
switch (elemSize)
{
case 1:
printf("\tdb\t%02Xh", *reinterpret_cast<uint8_t*>(&data->dsCont[i]));
printf("\tdb\t%02Xh", *reinterpret_cast<uint8_t*>(&data->Data()[i]));
for (j = 1; j < 16; j++)
{
if (i + j >= data->dsSize)
break;
printf(", %02Xh", *reinterpret_cast<uint8_t*>(&data->dsCont[i + j]));
printf(", %02Xh", *reinterpret_cast<uint8_t*>(&data->Data()[i + j]));
}
i += j;
break;
Expand All @@ -8703,12 +8704,12 @@ void emitter::emitDispDataSec(dataSecDsc* section, AllocMemChunk* dataChunks)
{
printf("\t<Unexpected data size %d (expected size%%2 == 0)\n", data->dsSize);
}
printf("\tdw\t%04Xh", *reinterpret_cast<uint16_t*>(&data->dsCont[i]));
printf("\tdw\t%04Xh", *reinterpret_cast<uint16_t*>(&data->Data()[i]));
for (j = 2; j < 24; j += 2)
{
if (i + j >= data->dsSize)
break;
printf(", %04Xh", *reinterpret_cast<uint16_t*>(&data->dsCont[i + j]));
printf(", %04Xh", *reinterpret_cast<uint16_t*>(&data->Data()[i + j]));
}
i += j;
break;
Expand All @@ -8719,12 +8720,12 @@ void emitter::emitDispDataSec(dataSecDsc* section, AllocMemChunk* dataChunks)
{
printf("\t<Unexpected data size %d (expected size%%4 == 0)\n", data->dsSize);
}
printf("\tdd\t%08Xh", *reinterpret_cast<uint32_t*>(&data->dsCont[i]));
printf("\tdd\t%08Xh", *reinterpret_cast<uint32_t*>(&data->Data()[i]));
for (j = 4; j < 24; j += 4)
{
if (i + j >= data->dsSize)
break;
printf(", %08Xh", *reinterpret_cast<uint32_t*>(&data->dsCont[i + j]));
printf(", %08Xh", *reinterpret_cast<uint32_t*>(&data->Data()[i + j]));
}
i += j;
break;
Expand All @@ -8737,12 +8738,12 @@ void emitter::emitDispDataSec(dataSecDsc* section, AllocMemChunk* dataChunks)
{
printf("\t<Unexpected data size %d (expected size%%8 == 0)\n", data->dsSize);
}
printf("\tdq\t%016llXh", *reinterpret_cast<uint64_t*>(&data->dsCont[i]));
printf("\tdq\t%016llXh", *reinterpret_cast<uint64_t*>(&data->Data()[i]));
for (j = 8; j < 64; j += 8)
{
if (i + j >= data->dsSize)
break;
printf(", %016llXh", *reinterpret_cast<uint64_t*>(&data->dsCont[i + j]));
printf(", %016llXh", *reinterpret_cast<uint64_t*>(&data->Data()[i + j]));
}
i += j;
break;
Expand Down
30 changes: 26 additions & 4 deletions src/coreclr/jit/emit.h
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Expand Up @@ -3555,10 +3555,32 @@ class emitter
sectionType dsType;
var_types dsDataType;

// variable-sized array used to store the constant data, BasicBlock*
// array in the block cases, or emitLocation for the asyncResumeInfo
// case.
BYTE dsCont[0];
private:
union
{
BYTE* dsData; // for data blobs
BasicBlock** dsBlocks; // for block-based sections
emitLocation* dsLocations; // for async resume info
};

public:
BYTE*& Data()
{
assert(dsType == sectionType::data);
return dsData;
}

BasicBlock**& Blocks()
{
assert((dsType == sectionType::blockAbsoluteAddr) || (dsType == sectionType::blockRelative32));
return dsBlocks;
}

emitLocation*& Locations()
{
assert(dsType == sectionType::asyncResumeInfo);
return dsLocations;
}
};

/* These describe the entire initialized/uninitialized data sections */
Expand Down
2 changes: 1 addition & 1 deletion src/coreclr/jit/emitarm.cpp
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Expand Up @@ -7326,7 +7326,7 @@ void emitter::emitDispInsHelp(
if (jdsc != nullptr && id->idIns() == INS_movt)
{
unsigned cnt = jdsc->dsSize / TARGET_POINTER_SIZE;
BasicBlock** bbp = (BasicBlock**)jdsc->dsCont;
BasicBlock** bbp = jdsc->Blocks();

bool isBound = (emitCodeGetCookie(*bbp) != nullptr);

Expand Down
2 changes: 1 addition & 1 deletion src/coreclr/jit/emitxarch.cpp
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Expand Up @@ -12347,7 +12347,7 @@ void emitter::emitDispAddrMode(instrDesc* id, bool noDetail) const
if (jdsc && !noDetail)
{
unsigned cnt = (jdsc->dsSize - 1) / TARGET_POINTER_SIZE;
BasicBlock** bbp = (BasicBlock**)jdsc->dsCont;
BasicBlock** bbp = jdsc->Blocks();

#ifdef TARGET_AMD64
#define SIZE_LETTER "Q"
Expand Down
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