[SYCL][FPGA] Remove support for intel::fpga_pipeline attribute (#6519)

Support for new FPGA attribute called [[intel::fpga_pipeline(N)]]
on #6254 is no longer needed.

This patch removes the support from frontend.

Signed-off-by: Soumi Manna <[email protected]>

Author: smanna12

clang/include/clang/Basic/Attr.td

@@ -2331,23 +2331,6 @@ def : MutualExclusions<[SYCLIntelFPGAIVDep,
 def : MutualExclusions<[SYCLIntelFPGAMaxConcurrency,
                         SYCLIntelFPGADisableLoopPipelining]>;
 
-def SYCLIntelFPGAPipeline : InheritableAttr {
-  let Spellings = [CXX11<"intel","fpga_pipeline">];
-  let Args = [ExprArgument<"Value", /*optional*/1>];
-  let LangOpts = [SYCLIsDevice, SilentlyIgnoreSYCLIsHost];
-  let Subjects = SubjectList<[ForStmt, CXXForRangeStmt, WhileStmt, DoStmt],
-                              ErrorDiag, "'for', 'while', and 'do' statements">;
-  let Documentation = [SYCLIntelFPGAPipelineAttrDocs];
-  let IsStmtDependent = 1;
-}
-
-def : MutualExclusions<[SYCLIntelFPGAInitiationInterval,
-                        SYCLIntelFPGAPipeline]>;
-def : MutualExclusions<[SYCLIntelFPGAIVDep,
-                        SYCLIntelFPGAPipeline]>;
-def : MutualExclusions<[SYCLIntelFPGAMaxConcurrency,
-                        SYCLIntelFPGAPipeline]>;
-
 def SYCLIntelFPGALoopCount : StmtAttr {
   let Spellings = [CXX11<"intel", "loop_count_min">,
                    CXX11<"intel", "loop_count_max">,
@@ -2380,9 +2363,6 @@ def SYCLIntelFPGAMaxInterleaving : StmtAttr {
 def : MutualExclusions<[SYCLIntelFPGADisableLoopPipelining,
                         SYCLIntelFPGAMaxInterleaving]>;
 
-def : MutualExclusions<[SYCLIntelFPGAPipeline,
-                        SYCLIntelFPGAMaxInterleaving]>;
-
 def SYCLIntelFPGASpeculatedIterations : StmtAttr {
   let Spellings = [CXX11<"intel", "speculated_iterations">];
   let Subjects = SubjectList<[ForStmt, CXXForRangeStmt, WhileStmt, DoStmt],
@@ -2395,9 +2375,6 @@ def SYCLIntelFPGASpeculatedIterations : StmtAttr {
 def : MutualExclusions<[SYCLIntelFPGADisableLoopPipelining,
                         SYCLIntelFPGASpeculatedIterations]>;
 
-def : MutualExclusions<[SYCLIntelFPGAPipeline,
-                        SYCLIntelFPGASpeculatedIterations]>;
-
 def SYCLIntelFPGANofusion : StmtAttr {
   let Spellings = [CXX11<"intel","nofusion">];
   let Subjects = SubjectList<[ForStmt, CXXForRangeStmt, WhileStmt, DoStmt],

clang/include/clang/Basic/AttrDocs.td

@@ -3328,58 +3328,6 @@ or ``ivdep``.
   }];
 }
 
-def SYCLIntelFPGAPipelineAttrDocs : Documentation {
-  let Category = DocCatVariable;
-  let Heading = "intel::fpga_pipeline";
-  let Content = [{
-The ``intel::fpga_pipeline(N)`` attribute applies to a loop and it allows users
-to disable or enable pipelining iterations of a loop. The attribute optionally
-accepts an integer constant expression that is converted to `bool`. A `true`
-value enables pipelining while a `false` value disables pipelining. The
-optional argument defaults to `true`. This attribute cannot be applied to a
-loop in conjunction with the  ``max_interleaving``, ``speculated_iterations``,
-``max_concurrency``, ``initiation_interval``, or ``ivdep`` attributes.
-
-.. code-block:: c++
-
-  // Disable loop pipelining
-  void bar() {
-    int a[10];
-    [[[intel::fpga_pipeline(0)]] for (int i = 0; i != 10; ++i) a[i] = 0;
-  }
-
-  // Enable loop pipelining
-  void foo() {
-    int var = 0;
-    [[intel::fpga_pipeline(1)]] for (int i = 0; i < 10; ++i) var++;
-  }
-
-  void Array(int *array, size_t n) {
-    // identical to [[intel::fpga_pipeline(1)]]
-    [[intel::fpga_pipeline]] for (int i = 0; i < n; ++i) array[i] = 0;
-  }
-
-  void count () {
-  int a1[10], int i = 0;
-  [[intel::fpga_pipeline(1)]] while (i < 10) {
-    a1[i] += 3;
-  }
-
-  void check() {
-    int a = 10;
-    [[intel::fpga_pipeline(1)]] do {
-      a = a + 1;
-    } while (a < 20);
-  }
-
-  template<int A>
-  void func() {
-    [[intel::fpga_pipeline(A)]] for(;;) { }
-  }
-
-  }];
-}
-
 def SYCLIntelFPGALoopCountAttrDocs : Documentation {
   let Category = DocCatVariable;
   let Heading = "intel::loop_count_min, intel::loop_count_max, intel::loop_count_avg, intel::loop_count";

clang/include/clang/Sema/Sema.h

@@ -2288,9 +2288,6 @@ class Sema final {
   SYCLIntelFPGALoopCoalesceAttr *
   BuildSYCLIntelFPGALoopCoalesceAttr(const AttributeCommonInfo &CI, Expr *E);
 
-  SYCLIntelFPGAPipelineAttr *
-  BuildSYCLIntelFPGAPipelineAttr(const AttributeCommonInfo &CI, Expr *E);
-
   bool CheckQualifiedFunctionForTypeId(QualType T, SourceLocation Loc);
 
   bool CheckFunctionReturnType(QualType T, SourceLocation Loc);

clang/lib/CodeGen/CGLoopInfo.cpp

@@ -612,13 +612,6 @@ MDNode *LoopInfo::createMetadata(
     LoopProperties.push_back(MDNode::get(Ctx, Vals));
   }
 
-  for (auto &FP : Attrs.SYCLIntelFPGAPipeline) {
-    Metadata *Vals[] = {MDString::get(Ctx, FP.first),
-                        ConstantAsMetadata::get(ConstantInt::get(
-                            llvm::Type::getInt32Ty(Ctx), FP.second))};
-    LoopProperties.push_back(MDNode::get(Ctx, Vals));
-  }
-
   LoopProperties.insert(LoopProperties.end(), AdditionalLoopProperties.begin(),
                         AdditionalLoopProperties.end());
   return createFullUnrollMetadata(Attrs, LoopProperties, HasUserTransforms);
@@ -662,7 +655,6 @@ void LoopAttributes::clear() {
   PipelineDisabled = false;
   PipelineInitiationInterval = 0;
   SYCLNofusionEnable = false;
-  SYCLIntelFPGAPipeline.clear();
   MustProgress = false;
 }
 
@@ -696,8 +688,7 @@ LoopInfo::LoopInfo(BasicBlock *Header, const LoopAttributes &Attrs,
       Attrs.UnrollEnable == LoopAttributes::Unspecified &&
       Attrs.UnrollAndJamEnable == LoopAttributes::Unspecified &&
       Attrs.DistributeEnable == LoopAttributes::Unspecified && !StartLoc &&
-      Attrs.SYCLNofusionEnable == false &&
-      Attrs.SYCLIntelFPGAPipeline.empty() && !EndLoc && !Attrs.MustProgress)
+      Attrs.SYCLNofusionEnable == false && !EndLoc && !Attrs.MustProgress)
     return;
 
   TempLoopID = MDNode::getTemporary(Header->getContext(), None);
@@ -1021,8 +1012,6 @@ void LoopInfoStack::push(BasicBlock *Header, clang::ASTContext &Ctx,
   // emitted
   // For attribute nofusion:
   // 'llvm.loop.fusion.disable' metadata will be emitted
-  // For attribute fpga_pipeline:
-  // n - 'llvm.loop.intel.pipelining.enable, i32 n' metadata will be emitted
   for (const auto *A : Attrs) {
     if (const auto *IntelFPGAIVDep = dyn_cast<SYCLIntelFPGAIVDepAttr>(A))
       addSYCLIVDepInfo(Header->getContext(), IntelFPGAIVDep->getSafelenValue(),
@@ -1087,15 +1076,6 @@ void LoopInfoStack::push(BasicBlock *Header, clang::ASTContext &Ctx,
 
     if (isa<SYCLIntelFPGANofusionAttr>(A))
       setSYCLNofusionEnable();
-
-    if (const auto *IntelFPGAPipeline =
-            dyn_cast<SYCLIntelFPGAPipelineAttr>(A)) {
-      const auto *CE = cast<ConstantExpr>(IntelFPGAPipeline->getValue());
-      Optional<llvm::APSInt> ArgVal = CE->getResultAsAPSInt();
-      unsigned int Value = ArgVal->getBoolValue() ? 1 : 0;
-      const char *Var = "llvm.loop.intel.pipelining.enable";
-      setSYCLIntelFPGAPipeline(Var, Value);
-    }
   }
 
   setMustProgress(MustProgress);

clang/lib/CodeGen/CGLoopInfo.h

@@ -152,10 +152,6 @@ struct LoopAttributes {
   /// Flag for llvm.loop.fusion.disable metatdata.
   bool SYCLNofusionEnable;
 
-  /// Value for fpga_pipeline variant and metadata.
-  llvm::SmallVector<std::pair<const char *, unsigned int>, 2>
-      SYCLIntelFPGAPipeline;
-
   /// Value for whether the loop is required to make progress.
   bool MustProgress;
 };
@@ -411,11 +407,6 @@ class LoopInfoStack {
   /// Set flag of nofusion for the next loop pushed.
   void setSYCLNofusionEnable() { StagedAttrs.SYCLNofusionEnable = true; }
 
-  /// Set variant and value of fpga_pipeline for the next loop pushed.
-  void setSYCLIntelFPGAPipeline(const char *Var, unsigned int Value) {
-    StagedAttrs.SYCLIntelFPGAPipeline.push_back({Var, Value});
-  }
-
   /// Set no progress for the next loop pushed.
   void setMustProgress(bool P) { StagedAttrs.MustProgress = P; }
 

clang/lib/Sema/SemaStmtAttr.cpp

@@ -219,33 +219,6 @@ static Attr *handleSYCLIntelFPGADisableLoopPipeliningAttr(Sema &S, Stmt *,
   return new (S.Context) SYCLIntelFPGADisableLoopPipeliningAttr(S.Context, A);
 }
 
-// Handle [[intel:fpga_pipeline]] attribute.
-static Attr *handleSYCLIntelFPGAPipelineAttr(Sema &S, Stmt *,
-                                             const ParsedAttr &A) {
-  // If no attribute argument is specified, set to default value '1'.
-  Expr *E = A.isArgExpr(0)
-                ? A.getArgAsExpr(0)
-                : IntegerLiteral::Create(S.Context, llvm::APInt(32, 1),
-                                         S.Context.IntTy, A.getLoc());
-
-  return S.BuildSYCLIntelFPGAPipelineAttr(A, E);
-}
-
-SYCLIntelFPGAPipelineAttr *
-Sema::BuildSYCLIntelFPGAPipelineAttr(const AttributeCommonInfo &A, Expr *E) {
-
-  if (!E->isValueDependent()) {
-    // Check if the expression is not value dependent.
-    llvm::APSInt ArgVal;
-    ExprResult Res = VerifyIntegerConstantExpression(E, &ArgVal);
-    if (Res.isInvalid())
-      return nullptr;
-    E = Res.get();
-  }
-
-  return new (Context) SYCLIntelFPGAPipelineAttr(Context, A, E);
-}
-
 static bool checkSYCLIntelFPGAIVDepSafeLen(Sema &S, llvm::APSInt &Value,
                                            Expr *E) {
   // This attribute requires a non-negative value.
@@ -855,7 +828,6 @@ static void CheckForIncompatibleSYCLLoopAttributes(
   CheckForDuplicationSYCLLoopAttribute<LoopUnrollHintAttr>(S, Attrs, false);
   CheckRedundantSYCLIntelFPGAIVDepAttrs(S, Attrs);
   CheckForDuplicationSYCLLoopAttribute<SYCLIntelFPGANofusionAttr>(S, Attrs);
-  CheckForDuplicationSYCLLoopAttribute<SYCLIntelFPGAPipelineAttr>(S, Attrs);
 }
 
 void CheckForIncompatibleUnrollHintAttributes(
@@ -1001,8 +973,6 @@ static Attr *ProcessStmtAttribute(Sema &S, Stmt *St, const ParsedAttr &A,
     return handleUnlikely(S, St, A, Range);
   case ParsedAttr::AT_SYCLIntelFPGANofusion:
     return handleIntelFPGANofusionAttr(S, St, A);
-  case ParsedAttr::AT_SYCLIntelFPGAPipeline:
-    return handleSYCLIntelFPGAPipelineAttr(S, St, A);
   default:
     // N.B., ClangAttrEmitter.cpp emits a diagnostic helper that ensures a
     // declaration attribute is not written on a statement, but this code is

clang/lib/Sema/SemaTemplateInstantiate.cpp

@@ -1112,8 +1112,6 @@ namespace {
         const SYCLIntelFPGASpeculatedIterationsAttr *SI);
     const SYCLIntelFPGALoopCountAttr *
     TransformSYCLIntelFPGALoopCountAttr(const SYCLIntelFPGALoopCountAttr *SI);
-    const SYCLIntelFPGAPipelineAttr *
-    TransformSYCLIntelFPGAPipelineAttr(const SYCLIntelFPGAPipelineAttr *SI);
 
     ExprResult TransformPredefinedExpr(PredefinedExpr *E);
     ExprResult TransformDeclRefExpr(DeclRefExpr *E);
@@ -1605,13 +1603,6 @@ const LoopUnrollHintAttr *TemplateInstantiator::TransformLoopUnrollHintAttr(
   return getSema().BuildLoopUnrollHintAttr(*LU, TransformedExpr);
 }
 
-const SYCLIntelFPGAPipelineAttr *
-TemplateInstantiator::TransformSYCLIntelFPGAPipelineAttr(
-    const SYCLIntelFPGAPipelineAttr *PA) {
-  Expr *TransformedExpr = getDerived().TransformExpr(PA->getValue()).get();
-  return getSema().BuildSYCLIntelFPGAPipelineAttr(*PA, TransformedExpr);
-}
-
 ExprResult TemplateInstantiator::transformNonTypeTemplateParmRef(
                                                  NonTypeTemplateParmDecl *parm,
                                                  SourceLocation loc,

clang/test/CodeGenSYCL/intel-fpga-loops.cpp

@@ -20,14 +20,6 @@
 // CHECK: br label %for.cond2, !llvm.loop ![[MD_LCA_1:[0-9]+]]
 // CHECK: br label %for.cond13, !llvm.loop ![[MD_LCA_2:[0-9]+]]
 // CHECK: br label %for.cond24, !llvm.loop ![[MD_LCA_3:[0-9]+]]
-// CHECK: br label %for.cond, !llvm.loop ![[MD_FP:[0-9]+]]
-// CHECK: br label %for.cond2, !llvm.loop ![[MD_FP_1:[0-9]+]]
-// CHECK: br label %for.cond13, !llvm.loop ![[MD_FP_2:[0-9]+]]
-// CHECK: br label %for.cond24, !llvm.loop ![[MD_FP_3:[0-9]+]]
-// CHECK: br label %while.cond, !llvm.loop ![[MD_FP_4:[0-9]+]]
-// CHECK: br i1 %cmp38, label %do.body, label %do.end, !llvm.loop ![[MD_FP_5:[0-9]+]]
-// CHECK: br label %for.cond40, !llvm.loop ![[MD_FP_6:[0-9]+]]
-// CHECK: br label %while.cond47, !llvm.loop ![[MD_FP_7:[0-9]+]]
 
 void disable_loop_pipelining() {
   int a[10];
@@ -134,7 +126,7 @@ void speculated_iterations() {
       a[i] = 0;
 }
 
-// Add CodeGen tests for FPGA loop attribute: [[intel::fpga_pipeline()]].
+// Add CodeGen tests for FPGA loop_count attributes.
 template <int A>
 void loop_count_control() {
   int a[10];
@@ -159,48 +151,6 @@ void loop_count_control() {
       a[i] = 0;
 }
 
-// Add CodeGen tests for Loop attribute: [[intel::fpga_pipeline()]].
-template <int A>
-void fpga_pipeline() {
-  int a[10];
-  // CHECK: ![[MD_FP]] = distinct !{![[MD_FP]], ![[MP]], ![[MD_fpga_pipeline:[0-9]+]]}
-  // CHECK-NEXT: ![[MD_fpga_pipeline]] = !{!"llvm.loop.intel.pipelining.enable", i32 1}
-  [[intel::fpga_pipeline(A)]] for (int i = 0; i != 10; ++i)
-    a[i] = 0;
-
-  // CHECK: ![[MD_FP_1]] = distinct !{![[MD_FP_1]], ![[MP]], ![[MD_fpga_pipeline]]}
-  [[intel::fpga_pipeline(1)]] for (int i = 0; i != 10; ++i)
-    a[i] = 0;
-
-  // CHECK: ![[MD_FP_2]] = distinct !{![[MD_FP_2]], ![[MP]], ![[MD_fpga_pipeline]]}
-  [[intel::fpga_pipeline]] for (int i = 0; i != 10; ++i)
-    a[i] = 0;
-
-  // CHECK: ![[MD_FP_3]] = distinct !{![[MD_FP_3]], ![[MP]], ![[MD_dlp]]}
-  [[intel::fpga_pipeline(0)]] for (int i = 0; i != 10; ++i)
-    a[i] = 0;
-
-  // CHECK: ![[MD_FP_4]] = distinct !{![[MD_FP_4]], ![[MP]], ![[MD_fpga_pipeline]]}
-  int j = 0;
-  [[intel::fpga_pipeline]] while (j < 10) {
-    a[j] += 3;
-  }
-
-  // CHECK: ![[MD_FP_5]] = distinct !{![[MD_FP_5]], ![[MP]], ![[MD_fpga_pipeline]]}
-  int b = 10;
-  [[intel::fpga_pipeline(1)]] do {
-    b = b + 1;
-  } while (b < 20);
-
-  // CHECK: ![[MD_FP_6]] = distinct !{![[MD_FP_6]], ![[MD_fpga_pipeline]]}
-  int c[] = {0, 1, 2, 3, 4, 5};
-  [[intel::fpga_pipeline(A)]] for (int n : c) { n *= 2; }
-
-  // CHECK: ![[MD_FP_7]] = distinct !{![[MD_FP_7]], ![[MP]], ![[MD_fpga_pipeline]]}
-  int k = 0;
-  [[intel::fpga_pipeline(-1)]] while (k < 20) { a[k] += 2; }
-}
-
 template <typename name, typename Func>
 __attribute__((sycl_kernel)) void kernel_single_task(const Func &kernelFunc) {
   kernelFunc();
@@ -216,7 +166,6 @@ int main() {
     max_interleaving<3, 0>();
     speculated_iterations<4, 0>();
     loop_count_control<12>();
-    fpga_pipeline<1>();
   });
   return 0;
 }