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Rename areAllFields32Or64BitBasicType to canExpandIndirectArgument to closer match what it is semantically used for. 

Also, fix a major bug where fields from a C++ struct might be dropped -- the expand action doesn't handle them correctly yet.

llvm-svn: 86502
This commit is contained in:
Daniel Dunbar 2009-11-09 01:33:53 +00:00
parent 96c0a3e6c2
commit 11c08c8e5b
1 changed files with 29 additions and 10 deletions
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39
clang/lib/CodeGen/TargetABIInfo.cpp
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@ -168,8 +168,28 @@ static bool is32Or64BitBasicType(QualType Ty, ASTContext &Context) {
return Size == 32 || Size == 64;
}
static bool areAllFields32Or64BitBasicType(const RecordDecl *RD,
ASTContext &Context) {
/// canExpandIndirectArgument - Test whether an argument type which is to be
/// passed indirectly (on the stack) would have the equivalent layout if it was
/// expanded into separate arguments. If so, we prefer to do the latter to avoid
/// inhibiting optimizations.
///
// FIXME: This predicate is missing many cases, currently it just follows
// llvm-gcc (checks that all fields are 32-bit or 64-bit primitive types). We
// should probably make this smarter, or better yet make the LLVM backend
// capable of handling it.
static bool canExpandIndirectArgument(QualType Ty, ASTContext &Context) {
// We can only expand structure types.
const RecordType *RT = Ty->getAs<RecordType>();
if (!RT)
return false;
// We can only expand (C) structures.
//
// FIXME: This needs to be generalized to handle classes as well.
const RecordDecl *RD = RT->getDecl();
if (!RD->isStruct() || isa<CXXRecordDecl>(RD))
return false;
for (RecordDecl::field_iterator i = RD->field_begin(), e = RD->field_end();
i != e; ++i) {
const FieldDecl *FD = *i;
@ -442,14 +462,13 @@ ABIArgInfo X86_32ABIInfo::classifyArgumentType(QualType Ty,
if (Ty->isStructureType() && Context.getTypeSize(Ty) == 0)
return ABIArgInfo::getIgnore();
// Expand structs with size <= 128-bits which consist only of
// basic types (int, long long, float, double, xxx*). This is
// non-recursive and does not ignore empty fields.
if (const RecordType *RT = Ty->getAsStructureType()) {
if (Context.getTypeSize(Ty) <= 4*32 &&
areAllFields32Or64BitBasicType(RT->getDecl(), Context))
return ABIArgInfo::getExpand();
}
// Expand small (<= 128-bit) record types when we know that the stack layout
// of those arguments will match the struct. This is important because the
// LLVM backend isn't smart enough to remove byval, which inhibits many
// optimizations.
if (Context.getTypeSize(Ty) <= 4*32 &&
canExpandIndirectArgument(Ty, Context))
return ABIArgInfo::getExpand();
return ABIArgInfo::getIndirect(getIndirectArgumentAlignment(Ty, Context));
} else {