diff options
Diffstat (limited to 'llvm/lib/Transforms/IPO/ArgumentPromotion.cpp')
| -rw-r--r-- | llvm/lib/Transforms/IPO/ArgumentPromotion.cpp | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp b/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp index c7c57ab5644..440f3f20d61 100644 --- a/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp +++ b/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp @@ -245,6 +245,24 @@ CallGraphNode *ArgPromotion::PromoteArguments(CallGraphNode *CGN) { Argument *PtrArg = PointerArgs[i]; Type *AgTy = cast<PointerType>(PtrArg->getType())->getElementType(); + // Replace sret attribute with noalias. This reduces register pressure by + // avoiding a register copy. + if (PtrArg->hasStructRetAttr()) { + unsigned ArgNo = PtrArg->getArgNo(); + F->setAttributes( + F->getAttributes() + .removeAttribute(F->getContext(), ArgNo + 1, Attribute::StructRet) + .addAttribute(F->getContext(), ArgNo + 1, Attribute::NoAlias)); + for (Use &U : F->uses()) { + CallSite CS(U.getUser()); + CS.setAttributes( + CS.getAttributes() + .removeAttribute(F->getContext(), ArgNo + 1, + Attribute::StructRet) + .addAttribute(F->getContext(), ArgNo + 1, Attribute::NoAlias)); + } + } + // If this is a byval argument, and if the aggregate type is small, just // pass the elements, which is always safe, if the passed value is densely // packed or if we can prove the padding bytes are never accessed. This does |
