x86_64 ABI: Implement classification for bit-fields.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@64727 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGCall.cpp b/lib/CodeGen/CGCall.cpp
index 6f22adf..9c7991d 100644
--- a/lib/CodeGen/CGCall.cpp
+++ b/lib/CodeGen/CGCall.cpp
@@ -620,10 +620,13 @@
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 @@
// 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)