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x86_64 ABI: Implement classification for bit-fields. 

llvm-svn: 64727
This commit is contained in:
Daniel Dunbar 2009-02-17 02:45:44 +00:00
parent 325dec7343
commit 7f0e2368bb
1 changed files with 26 additions and 2 deletions
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28
clang/lib/CodeGen/CGCall.cpp
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@ -620,10 +620,13 @@ void X86_64ABIInfo::classify(QualType Ty,
for (RecordDecl::field_iterator i = RD->field_begin(),
e = RD->field_end(); i != e; ++i, ++idx) {
uint64_t Offset = OffsetBase + Layout.getFieldOffset(idx);
bool BitField = i->isBitField();
// AMD64-ABI 3.2.3p2: Rule 1. If ..., or it contains unaligned
// fields, it has class MEMORY.
if (Offset % Context.getTypeAlign(i->getType())) {
//
// Note, skip this test for bitfields, see below.
if (!BitField && Offset % Context.getTypeAlign(i->getType())) {
Lo = Memory;
return;
}
@ -635,7 +638,28 @@ void X86_64ABIInfo::classify(QualType Ty,
// separately. Each eightbyte gets initialized to class
// NO_CLASS.
Class FieldLo, FieldHi;
classify(i->getType(), Context, Offset, FieldLo, FieldHi);
// Bitfields require special handling, they do not force the
// structure to be passed in memory even if unaligned, and
// therefore they can straddle an eightbyte.
if (BitField) {
uint64_t Offset = OffsetBase + Layout.getFieldOffset(idx);
uint64_t Size =
i->getBitWidth()->getIntegerConstantExprValue(Context).getZExtValue();
uint64_t EB_Lo = Offset / 64;
uint64_t EB_Hi = (Offset + Size - 1) / 64;
FieldLo = FieldHi = NoClass;
if (EB_Lo) {
assert(EB_Hi == EB_Lo && "Invalid classification, type > 16 bytes.");
FieldLo = NoClass;
FieldHi = Integer;
} else {
FieldLo = Integer;
FieldHi = EB_Hi ? Integer : NoClass;
}
} else
classify(i->getType(), Context, Offset, FieldLo, FieldHi);
Lo = merge(Lo, FieldLo);
Hi = merge(Hi, FieldHi);
if (Lo == Memory || Hi == Memory)