[SYCL][FPGA] Add mutual diagnostic of max_concurrency attribute in conjunction of disable_loop_pipelining attribute (#3512)

This patch
  1. removes FIXME and adds mutual diagnostic of max_concurrency and disable_loop_pipelining attributes.
  2. updates document
  3. adds tests

Signed-off-by: Soumi Manna <soumi.manna@intel.com>

Author: smanna12

clang/include/clang/Basic/Attr.td

@@ -1957,6 +1957,9 @@ def : MutualExclusions<[SYCLIntelFPGAIVDep,
 def : MutualExclusions<[SYCLIntelFPGAMaxConcurrency,
                         SYCLIntelFPGADisableLoopPipelining]>;
 
+def : MutualExclusions<[SYCLIntelFPGAMaxConcurrency,
+                        SYCLIntelFPGADisableLoopPipelining]>;
+
 def SYCLIntelFPGAMaxInterleaving : StmtAttr {
   let Spellings = [CXX11<"intelfpga","max_interleaving">,
                    CXX11<"intel","max_interleaving">];

clang/include/clang/Basic/AttrDocs.td

@@ -2869,7 +2869,7 @@ This attribute applies to a loop or a function. It indicates that the
 loop/function should allow no more than N threads or iterations to execute it
 simultaneously. N must be a non negative integer. '0' indicates the
 max_concurrency case to be unbounded. Cannot be applied multiple times to the
-same loop.
+same loop or function, or in conjunction with ``disable_loop_pipelining``.
 
 .. code-block:: c++
 
@@ -2935,17 +2935,18 @@ def SYCLIntelFPGADisableLoopPipeliningAttrDocs : Documentation {
 This attribute applies to a loop or a function. Takes no arguments and
 disables pipelining of the loop or function data path, causing the loop
 or function to be executed serially. Cannot be used on the same loop or
-function in conjunction with max_interleaving, speculated_iterations,
-max_concurrency, initiation_interval, or ivdep.
+function, or in conjunction with ``max_interleaving``,
+``speculated_iterations``, ``max_concurrency``, ``initiation_interval``,
+or ``ivdep``.
 
 .. code-block:: c++
 
   void foo() {
     int var = 0;
-    [[intel::disable_loop_pipelining] for (int i = 0; i < 10; ++i) var++;
+    [[intel::disable_loop_pipelining]] for (int i = 0; i < 10; ++i) var++;
   }
 
-  [[intel::disable_loop_pipelining] void foo1() { }
+  [[intel::disable_loop_pipelining]] void foo1() { }
 
   }];
 }

clang/lib/Sema/SemaDeclAttr.cpp

@@ -6292,12 +6292,6 @@ SYCLIntelFPGAMaxConcurrencyAttr *Sema::MergeSYCLIntelFPGAMaxConcurrencyAttr(
     }
     return nullptr;
   }
-  // FIXME
-  // max_concurrency and disable_component_pipelining attributes can't be
-  // applied to the same function. Upcoming patch needs to have this code
-  // added to it:
-  // if (checkAttrMutualExclusion<IntelDisableComponentPipeline>(S, D, AL))
-  //  return;
 
   return ::new (Context)
       SYCLIntelFPGAMaxConcurrencyAttr(Context, A, A.getNThreadsExpr());
@@ -6337,12 +6331,6 @@ void Sema::AddSYCLIntelFPGAMaxConcurrencyAttr(Decl *D,
 static void handleSYCLIntelFPGAMaxConcurrencyAttr(Sema &S, Decl *D,
                                                   const ParsedAttr &A) {
   S.CheckDeprecatedSYCLAttributeSpelling(A);
-  // FIXME
-  // max_concurrency and disable_component_pipelining attributes can't be
-  // applied to the same function. Upcoming patch needs to have this code
-  // added to it:
-  // if (checkAttrMutualExclusion<IntelDisableComponentPipeline>(S, D, AL))
-  //  return;
 
   Expr *E = A.getArgAsExpr(0);
   S.AddSYCLIntelFPGAMaxConcurrencyAttr(D, A, E);

clang/test/SemaSYCL/max-concurrency.cpp

@@ -16,6 +16,20 @@ class Functor1 {
 
 [[intel::max_concurrency]] void foo() {} // expected-error {{'max_concurrency' attribute takes one argument}}
 
+// Tests for Intel FPGA max_concurrency and disable_loop_pipelining function attributes compatibility.
+// expected-error@+2 {{'max_concurrency' and 'disable_loop_pipelining' attributes are not compatible}}
+// expected-note@+1 {{conflicting attribute is here}}
+[[intel::disable_loop_pipelining]] [[intel::max_concurrency(2)]] void check();
+
+// expected-error@+2 {{'disable_loop_pipelining' and 'max_concurrency' attributes are not compatible}}
+// expected-note@+1 {{conflicting attribute is here}}
+[[intel::max_concurrency(4)]] [[intel::disable_loop_pipelining]] void check1();
+
+// expected-error@+3 {{'disable_loop_pipelining' and 'max_concurrency' attributes are not compatible}}
+// expected-note@+1 {{conflicting attribute is here}}
+[[intel::max_concurrency(4)]] void check2();
+[[intel::disable_loop_pipelining]] void check2();
+
 class Functor2 {
 public:
   void operator()() const {

clang/utils/TableGen/ClangAttrEmitter.cpp

@@ -3695,6 +3695,11 @@ static void GenerateMutualExclusionsChecks(const Record &Attr,
     }
   }
 
+  // If there are any decl or stmt attributes, silence -Woverloaded-virtual
+  // warnings for them both.
+  if (!DeclAttrs.empty() || !StmtAttrs.empty())
+    OS << "  using ParsedAttrInfo::diagMutualExclusion;\n\n";
+
   // If we discovered any decl or stmt attributes to test for, generate the
   // predicates for them now.
   if (!DeclAttrs.empty()) {