[mips] Zero-sized structs cannot be ignored in MipsABIInfo::classifyReturnType() for O32
Summary:
They are returned indirectly which causes the other arguments to move to
the next argument slot.
With this, utils/ABITest does not discover any failing cases in the first
500 attempts on big/little endian for O32. Previously some of these failed.
Also tested N32/N64 little endian (big endian has other known issues) with
no issues.
Reviewers: atanasyan
Reviewed By: atanasyan
Subscribers: atanasyan, cfe-commits
Differential Revision: http://reviews.llvm.org/D4811
llvm-svn: 217147
diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp
index fb3b931..d33d6a0 100644
--- a/clang/lib/CodeGen/TargetInfo.cpp
+++ b/clang/lib/CodeGen/TargetInfo.cpp
@@ -5548,7 +5548,12 @@
ABIArgInfo MipsABIInfo::classifyReturnType(QualType RetTy) const {
uint64_t Size = getContext().getTypeSize(RetTy);
- if (RetTy->isVoidType() || Size == 0)
+ if (RetTy->isVoidType())
+ return ABIArgInfo::getIgnore();
+
+ // O32 doesn't treat zero-sized structs differently from other structs.
+ // However, N32/N64 ignores zero sized return values.
+ if (!IsO32 && Size == 0)
return ABIArgInfo::getIgnore();
if (isAggregateTypeForABI(RetTy) || RetTy->isVectorType()) {