Add two new pragmas for controlling software pipelining optimizations.

This patch adds #pragma clang loop pipeline and #pragma clang loop pipeline_initiation_interval for debugging or reducing compile time purposes. It is possible to disable SWP for concrete loops to save compilation time or to find bugs by not doing SWP to certain loops. It is possible to set value of initiation interval to concrete number to save compilation time by not doing extra pipeliner passes or to check created schedule for specific initiation interval.

Patch by Alexey Lapshin.

llvm-svn: 350414

1 files changed, 25 insertions, 11 deletions

diff --git a/clang/lib/Sema/SemaStmtAttr.cpp b/clang/lib/Sema/SemaStmtAttr.cpp
index 91f79971662..a8e54b36b29 100644
--- a/clang/lib/Sema/SemaStmtAttr.cpp
+++ b/clang/lib/Sema/SemaStmtAttr.cpp
@@ -147,11 +147,15 @@ static Attr *handleLoopHintAttr(Sema &S, Stmt *St, const ParsedAttr &A,
                  .Case("interleave_count", LoopHintAttr::InterleaveCount)
                  .Case("unroll", LoopHintAttr::Unroll)
                  .Case("unroll_count", LoopHintAttr::UnrollCount)
+                 .Case("pipeline", LoopHintAttr::PipelineDisabled)
+                 .Case("pipeline_initiation_interval",
+                       LoopHintAttr::PipelineInitiationInterval)
                  .Case("distribute", LoopHintAttr::Distribute)
                  .Default(LoopHintAttr::Vectorize);
     if (Option == LoopHintAttr::VectorizeWidth ||
         Option == LoopHintAttr::InterleaveCount ||
-        Option == LoopHintAttr::UnrollCount) {
+        Option == LoopHintAttr::UnrollCount ||
+        Option == LoopHintAttr::PipelineInitiationInterval) {
       assert(ValueExpr && "Attribute must have a valid value expression.");
       if (S.CheckLoopHintExpr(ValueExpr, St->getBeginLoc()))
         return nullptr;
@@ -159,7 +163,8 @@ static Attr *handleLoopHintAttr(Sema &S, Stmt *St, const ParsedAttr &A,
     } else if (Option == LoopHintAttr::Vectorize ||
                Option == LoopHintAttr::Interleave ||
                Option == LoopHintAttr::Unroll ||
-               Option == LoopHintAttr::Distribute) {
+               Option == LoopHintAttr::Distribute ||
+               Option == LoopHintAttr::PipelineDisabled) {
       assert(StateLoc && StateLoc->Ident && "Loop hint must have an argument");
       if (StateLoc->Ident->isStr("disable"))
         State = LoopHintAttr::Disable;
@@ -182,9 +187,9 @@ static Attr *handleLoopHintAttr(Sema &S, Stmt *St, const ParsedAttr &A,
 static void
 CheckForIncompatibleAttributes(Sema &S,
                                const SmallVectorImpl<const Attr *> &Attrs) {
-  // There are 5 categories of loop hints attributes: vectorize, interleave,
-  // unroll, unroll_and_jam and distribute. Except for distribute they come
-  // in two variants: a state form and a numeric form.  The state form
+  // There are 6 categories of loop hints attributes: vectorize, interleave,
+  // unroll, unroll_and_jam, pipeline and distribute. Except for distribute they
+  // come in two variants: a state form and a numeric form.  The state form
   // selectively defaults/enables/disables the transformation for the loop
   // (for unroll, default indicates full unrolling rather than enabling the
   // transformation). The numeric form form provides an integer hint (for
@@ -194,11 +199,8 @@ CheckForIncompatibleAttributes(Sema &S,
   struct {
     const LoopHintAttr *StateAttr;
     const LoopHintAttr *NumericAttr;
-  } HintAttrs[] = {{nullptr, nullptr},
-                   {nullptr, nullptr},
-                   {nullptr, nullptr},
-                   {nullptr, nullptr},
-                   {nullptr, nullptr}};
+  } HintAttrs[] = {{nullptr, nullptr}, {nullptr, nullptr}, {nullptr, nullptr},
+                   {nullptr, nullptr}, {nullptr, nullptr}, {nullptr, nullptr}};
 
   for (const auto *I : Attrs) {
     const LoopHintAttr *LH = dyn_cast<LoopHintAttr>(I);
@@ -208,7 +210,14 @@ CheckForIncompatibleAttributes(Sema &S,
       continue;
 
     LoopHintAttr::OptionType Option = LH->getOption();
-    enum { Vectorize, Interleave, Unroll, UnrollAndJam, Distribute } Category;
+    enum {
+      Vectorize,
+      Interleave,
+      Unroll,
+      UnrollAndJam,
+      Distribute,
+      Pipeline
+    } Category;
     switch (Option) {
     case LoopHintAttr::Vectorize:
     case LoopHintAttr::VectorizeWidth:
@@ -230,6 +239,10 @@ CheckForIncompatibleAttributes(Sema &S,
       // Perform the check for duplicated 'distribute' hints.
       Category = Distribute;
       break;
+    case LoopHintAttr::PipelineDisabled:
+    case LoopHintAttr::PipelineInitiationInterval:
+      Category = Pipeline;
+      break;
     };
 
     assert(Category < sizeof(HintAttrs) / sizeof(HintAttrs[0]));
@@ -238,6 +251,7 @@ CheckForIncompatibleAttributes(Sema &S,
     if (Option == LoopHintAttr::Vectorize ||
         Option == LoopHintAttr::Interleave || Option == LoopHintAttr::Unroll ||
         Option == LoopHintAttr::UnrollAndJam ||
+        Option == LoopHintAttr::PipelineDisabled ||
         Option == LoopHintAttr::Distribute) {
       // Enable|Disable|AssumeSafety hint.  For example, vectorize(enable).
       PrevAttr = CategoryState.StateAttr;