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BinTools: classify every eightbyte of small objects on System V x86_64 #10

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BinTools: classify every eightbyte of small objects on System V x86_64 #10

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35 changes: 13 additions & 22 deletions extensions/bintools/jit_call_x64.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -685,31 +685,22 @@ inline int ClassifyObject(const PassInfo *info, ObjectClass *classes)
{
numWords = int((info->size + 7) / 8);

unsigned int j = 0;
// Each eightbyte gets the merged class of every field laid out in it (fields are
// naturally aligned, in declaration order). E.g. Vector { float x, y, z; } is
// SSE (x, y) + SSE (z), returned in xmm0 + xmm1.
for (int i = 0; i < numWords; i++)
{
classes[i] = ObjectClass::None;
size_t sizeSoFar = 0;
for (int k = 0; j < numFields; j++, k++)
{
size_t sz = TypeSize(fields[j]);
if (sizeSoFar + sz > 8)
break;
else
sizeSoFar += sz;

if (k == 0 && sizeSoFar == 8) {
classes[i] = ClassifyType(fields[j++]);
break;
} else if (j + 1 >= numFields) {
break;
}

const ObjectField &field1 = fields[j];
const ObjectField &field2 = fields[j + 1];

classes[i] = MergeClasses(ClassifyType(field1), ClassifyType(field2));
}
size_t fieldOffset = 0;
for (unsigned int j = 0; j < numFields; j++)
{
size_t sz = TypeSize(fields[j]);
fieldOffset = (fieldOffset + sz - 1) & ~(sz - 1);
size_t word = fieldOffset / 8;
if (word >= (size_t)numWords)
break;
classes[word] = MergeClasses(classes[word], ClassifyType(fields[j]));
fieldOffset += sz;
}
}

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