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<!doctype html><html lang=en-us><head><meta charset=utf-8><meta http-equiv=x-ua-compatible content="IE=edge"><meta name=viewport content="width=device-width,initial-scale=1,maximum-scale=1,user-scalable=no"><title>Constraints - MLIR</title><meta name=description content="Multi-Level IR Compiler Framework"><meta name=generator content="Hugo 0.119.0"><link href=https://mlir.llvm.org/index.xml rel=alternate type=application/rss+xml><link rel=canonical href=https://mlir.llvm.org/docs/DefiningDialects/Constraints/><link rel=stylesheet href=https://mlir.llvm.org/css/theme.css><script src=https://use.fontawesome.com/releases/v5.0.6/js/all.js></script> <link rel=stylesheet href=https://mlir.llvm.org/css/chroma.min.css><script src=https://cdn.jsdelivr.net/npm/jquery@3.3.1/dist/jquery.min.js></script> <script src=https://cdn.jsdelivr.net/npm/jquery.easing@1.4.1/jquery.easing.min.js></script> <script src=https://mlir.llvm.org/js/bundle.js></script> <script type=text/javascript src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script> <script type=text/x-mathjax-config> MathJax.Hub.Config({ tex2jax: { inlineMath: [['$', '$'] ], displayMath: [ ['$$','$$'], ["\\[","\\]"] ] } }); </script><link rel=apple-touch-icon sizes=180x180 href="/apple-touch-icon.png?v=1"><link rel=icon type=image/png sizes=32x32 href="/favicon-32x32.png?v=1"><link rel=icon type=image/png sizes=16x16 href="/favicon-16x16.png?v=1"><link rel=manifest href="/site.webmanifest?v=1"><link rel=mask-icon href="/safari-pinned-tab.svg?v=1" color=#3775e0><link rel="shortcut icon" href="/favicon.ico?v=1"><meta name=msapplication-TileColor content="#2d89ef"><meta name=theme-color content="#ffffff"><link rel=icon href=/favicon.svg type=image/svg+xml sizes=any><style>:root{}</style></head><body><div class=container><header><h1><div><img src=https://mlir.llvm.org//mlir-logo.png width=40px align=absmiddle> MLIR</div></h1>Multi-Level IR Compiler Framework</header><div class=global-menu><nav><ul><li class=parent><a href>Community</a><ul class=sub-menu><li class=child><a href=https://llvm.discourse.group/c/mlir/31>Forums</a></li><li class=child><a href=https://discord.gg/xS7Z362>Chat</a></li></ul></li><li><a href=/getting_started/Debugging/>Debugging Tips</a></li><li><a href=/getting_started/Faq/>FAQ</a></li><li class=parent><a href=https://github.com/llvm/llvm-project/tree/main/mlir>Source</a><ul class=sub-menu><li class=child><a href=/doxygen/>Doxygen</a></li><li class=child><a href=https://github.com/llvm/llvm-project/tree/main/mlir>GitHub</a></li></ul></li><li><a href="https://bugs.llvm.org/buglist.cgi?bug_status=__open__&list_id=177877&order=changeddate%20DESC%2Cpriority%2Cbug_severity&product=MLIR&query_format=specific">Bugs</a></li><li><a href=https://github.com/llvm/mlir-www/tree/main/website/static/LogoAssets>Logo Assets</a></li><li><a href=https://www.youtube.com/MLIRCompiler>Youtube Channel</a></li></ul></nav></div><div class=content-container><main><h1>Constraints</h1><nav id=TableOfContents><ul><li><a href=#attribute--type-constraints>Attribute / Type Constraints</a></li></ul></nav><h2 id=attribute--type-constraints>Attribute / Type Constraints <a class=headline-hash href=#attribute--type-constraints>¶</a></h2>When defining the arguments of an operation in TableGen, users can specify either plain attributes/types or use attribute/type constraints to levy additional requirements on the attribute value or operand type.<div class=highlight><pre tabindex=0 class=chroma><code class=language-tablegen data-lang=tablegen>def My_Type1 : MyDialect_Type<"Type1", "type1"> { ... } def My_Type2 : MyDialect_Type<"Type2", "type2"> { ... } // Plain type let arguments = (ins MyType1:$val); // Type constraint let arguments = (ins AnyTypeOf<[MyType1, MyType2]>:$val); </code></pre></div><code>AnyTypeOf</code> is an example for a type constraints. Many useful type constraints can be found in <code>mlir/IR/CommonTypeConstraints.td</code>. Additional verification code is generated for type/attribute constraints. Type constraints can not only be used when defining operation arguments, but also when defining type parameters.Optionally, C++ functions can be generated, so that type constraints can be checked from C++. The name of the C++ function must be specified in the <code>cppFunctionName</code> field. If no function name is specified, no C++ function is emitted.<div class=highlight><pre tabindex=0 class=chroma><code class=language-tablegen data-lang=tablegen>// Example: Element type constraint for VectorType def Builtin_VectorTypeElementType : AnyTypeOf<[AnyInteger, Index, AnyFloat]> { let cppFunctionName = "isValidVectorTypeElementType"; } </code></pre></div>The above example tranlates into the following C++ code:<div class=highlight><pre tabindex=0 class=chroma><code class=language-c++ data-lang=c++>bool isValidVectorTypeElementType(::mlir::Type type) { return (((::llvm::isa<::mlir::IntegerType>(type))) || ((::llvm::isa<::mlir::IndexType>(type))) || ((::llvm::isa<::mlir::FloatType>(type)))); } </code></pre></div>An extra TableGen rule is needed to emit C++ code for type constraints. This will generate only the declarations/definitions of the type constaraints that are defined in the specified <code>.td</code> file, but not those that are in included <code>.td</code> files.<div class=highlight><pre tabindex=0 class=chroma><code class=language-cmake data-lang=cmake>mlir_tablegen(<Your Dialect>TypeConstraints.h.inc -gen-type-constraint-decls) mlir_tablegen(<Your Dialect>TypeConstraints.cpp.inc -gen-type-constraint-defs) </code></pre></div>The generated <code><Your Dialect>TypeConstraints.h.inc</code> will need to be included whereever you are referencing the type constraint in C++. Note that no C++ namespace will be emitted by the code generator. 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