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| -rw-r--r-- | llvm/docs/LangRef.rst | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst index 0612d360558..197439f5750 100644 --- a/llvm/docs/LangRef.rst +++ b/llvm/docs/LangRef.rst @@ -4412,12 +4412,20 @@ instructions (loads, stores, memory-accessing calls, etc.) that carry ``noalias`` metadata can specifically be specified not to alias with some other collection of memory access instructions that carry ``alias.scope`` metadata. Each type of metadata specifies a list of scopes where each scope has an id and -a domain. When evaluating an aliasing query, if for some domain, the set +a domain. + +When evaluating an aliasing query, if for some domain, the set of scopes with that domain in one instruction's ``alias.scope`` list is a subset of (or equal to) the set of scopes for that domain in another instruction's ``noalias`` list, then the two memory accesses are assumed not to alias. +Because scopes in one domain don't affect scopes in other domains, separate +domains can be used to compose multiple independent noalias sets. This is +used for example during inlining. As the noalias function parameters are +turned into noalias scope metadata, a new domain is used every time the +function is inlined. + The metadata identifying each domain is itself a list containing one or two entries. The first entry is the name of the domain. Note that if the name is a string then it can be combined across functions and translation units. A |
