Fix argument count check for ops with only a variadic argument list.

We don't count variadic arguments in the `getNumFullArguments()` method
since they can be zero. Not properly checking the return value of this
function can however lead to a `arg_size() < 0` check in the generated
verifier method. This happens if we only have a single variadic argument
list argument.

Author: Thomas Symalla

lib/TableGen/Operations.cpp

@@ -463,9 +463,17 @@ void Operation::emitVerifierMethod(llvm::raw_ostream &out,
   fmt.withContext(symbols.chooseName("context"));
   fmt.addSubst("_errs", symbols.chooseName("errs"));
 
+  bool emitArgCountVerifier = true;
   if (m_hasVariadicArgument) {
-    fmt.addSubst("_comparator", "<");
-    fmt.addSubst("_at_least", "at least ");
+    if (getNumFullArguments() == 0) {
+      // If the only argument in an operation is a variadic argument list,
+      // getNumFullArguments() will return zero. Thus, prevent us from emitting
+      // arg_size() < 0 verifier checks.
+      emitArgCountVerifier = false;
+    } else {
+      fmt.addSubst("_comparator", "<");
+      fmt.addSubst("_at_least", "at least ");
+    }
   } else {
     fmt.addSubst("_comparator", "!=");
     fmt.addSubst("_at_least", "");
@@ -477,14 +485,19 @@ void Operation::emitVerifierMethod(llvm::raw_ostream &out,
       (void)$_context;
 
       using ::llvm_dialects::printable;
+  )",
+               &fmt);
 
+  if (emitArgCountVerifier) {
+    out << tgfmt(R"(
       if (arg_size() $_comparator $0) {
         $_errs << "  wrong number of arguments: " << arg_size()
                << ", expected $_at_least$0\n";
         return false;
       }
   )",
-               &fmt, getNumFullArguments());
+                 &fmt, getNumFullArguments());
+  }
 
   Assignment assignment;
   Evaluator eval(symbols, assignment, m_system, out, fmt);

test/example/generated/ExampleDialect.cpp.inc

@@ -368,7 +368,7 @@ rhs,
       (void)context;
 
       using ::llvm_dialects::printable;
-
+  
       if (arg_size() != 3) {
         errs << "  wrong number of arguments: " << arg_size()
                << ", expected 3\n";
@@ -487,7 +487,7 @@ rhs
       (void)context;
 
       using ::llvm_dialects::printable;
-
+  
       if (arg_size() != 2) {
         errs << "  wrong number of arguments: " << arg_size()
                << ", expected 2\n";
@@ -582,7 +582,7 @@ index
       (void)context;
 
       using ::llvm_dialects::printable;
-
+  
       if (arg_size() != 2) {
         errs << "  wrong number of arguments: " << arg_size()
                << ", expected 2\n";
@@ -685,7 +685,7 @@ source
       (void)context;
 
       using ::llvm_dialects::printable;
-
+  
       if (arg_size() != 1) {
         errs << "  wrong number of arguments: " << arg_size()
                << ", expected 1\n";
@@ -849,7 +849,7 @@ source
       (void)context;
 
       using ::llvm_dialects::printable;
-
+  
       if (arg_size() != 0) {
         errs << "  wrong number of arguments: " << arg_size()
                << ", expected 0\n";
@@ -917,7 +917,7 @@ source
       (void)context;
 
       using ::llvm_dialects::printable;
-
+  
       if (arg_size() != 1) {
         errs << "  wrong number of arguments: " << arg_size()
                << ", expected 1\n";
@@ -1015,7 +1015,7 @@ source
       (void)context;
 
       using ::llvm_dialects::printable;
-
+  
       if (arg_size() != 1) {
         errs << "  wrong number of arguments: " << arg_size()
                << ", expected 1\n";
@@ -1184,7 +1184,7 @@ index
       (void)context;
 
       using ::llvm_dialects::printable;
-
+  
       if (arg_size() != 3) {
         errs << "  wrong number of arguments: " << arg_size()
                << ", expected 3\n";
@@ -1302,7 +1302,7 @@ instName_0
       (void)context;
 
       using ::llvm_dialects::printable;
-
+  
       if (arg_size() != 2) {
         errs << "  wrong number of arguments: " << arg_size()
                << ", expected 2\n";
@@ -1385,7 +1385,7 @@ instName
       (void)context;
 
       using ::llvm_dialects::printable;
-
+  
       if (arg_size() != 1) {
         errs << "  wrong number of arguments: " << arg_size()
                << ", expected 1\n";
@@ -1461,12 +1461,6 @@ instName
       (void)context;
 
       using ::llvm_dialects::printable;
-
-      if (arg_size() < 0) {
-        errs << "  wrong number of arguments: " << arg_size()
-               << ", expected at least 0\n";
-        return false;
-      }
   ::llvm::Type * const resultType = getResult()->getType();
 (void)resultType;
 
@@ -1531,7 +1525,7 @@ instName
       (void)context;
 
       using ::llvm_dialects::printable;
-
+  
       if (arg_size() != 0) {
         errs << "  wrong number of arguments: " << arg_size()
                << ", expected 0\n";
@@ -1588,7 +1582,7 @@ instName
       (void)context;
 
       using ::llvm_dialects::printable;
-
+  
       if (arg_size() != 0) {
         errs << "  wrong number of arguments: " << arg_size()
                << ", expected 0\n";
@@ -1645,7 +1639,7 @@ data
       (void)context;
 
       using ::llvm_dialects::printable;
-
+  
       if (arg_size() != 1) {
         errs << "  wrong number of arguments: " << arg_size()
                << ", expected 1\n";
@@ -1708,7 +1702,7 @@ data
       (void)context;
 
       using ::llvm_dialects::printable;
-
+  
       if (arg_size() != 1) {
         errs << "  wrong number of arguments: " << arg_size()
                << ", expected 1\n";
@@ -1787,7 +1781,7 @@ initial
       (void)context;
 
       using ::llvm_dialects::printable;
-
+  
       if (arg_size() != 3) {
         errs << "  wrong number of arguments: " << arg_size()
                << ", expected 3\n";
@@ -1879,7 +1873,7 @@ initial
       (void)context;
 
       using ::llvm_dialects::printable;
-
+  
       if (arg_size() != 3) {
         errs << "  wrong number of arguments: " << arg_size()
                << ", expected 3\n";
@@ -1971,7 +1965,7 @@ initial
       (void)context;
 
       using ::llvm_dialects::printable;
-
+  
       if (arg_size() != 3) {
         errs << "  wrong number of arguments: " << arg_size()
                << ", expected 3\n";
@@ -2058,7 +2052,7 @@ data
       (void)context;
 
       using ::llvm_dialects::printable;
-
+  
       if (arg_size() != 1) {
         errs << "  wrong number of arguments: " << arg_size()
                << ", expected 1\n";
@@ -2123,7 +2117,7 @@ data
       (void)context;
 
       using ::llvm_dialects::printable;
-
+  
       if (arg_size() < 1) {
         errs << "  wrong number of arguments: " << arg_size()
                << ", expected at least 1\n";