commit a48f58c97feca138f772e2cf122f229d6e341d82
author Sjoerd Meijer <sjoerd.meijer@arm.com> Thu Jul 25 07:33:13 2019 +0000
committer Sjoerd Meijer <sjoerd.meijer@arm.com> Thu Jul 25 07:33:13 2019 +0000
tree cbbebea1d0812d3b8092c53429aa27b1fb332f55
parent 3e023a6dbceca8dba9763d102079aff0d9861e05

[Clang] New loop pragma vectorize_predicate

This adds a new vectorize predication loop hint:

  #pragma clang loop vectorize_predicate(enable)

that can be used to indicate to the vectoriser that all (load/store)
instructions should be predicated (masked). This allows, for example, folding
of the remainder loop into the main loop.

This patch will be followed up with D64916 and D65197. The former is a
refactoring in the loopvectorizer and the groundwork to make tail loop folding
a more general concept, and in the latter the actual tail loop folding
transformation will be implemented.

Differential Revision: https://reviews.llvm.org/D64744

llvm-svn: 366989

clang/lib/Sema/SemaStmtAttr.cpp

diff --git a/clang/lib/Sema/SemaStmtAttr.cpp b/clang/lib/Sema/SemaStmtAttr.cpp
index 791c52c..e819d96 100644
--- a/clang/lib/Sema/SemaStmtAttr.cpp
+++ b/clang/lib/Sema/SemaStmtAttr.cpp
@@ -133,6 +133,7 @@
                  .Case("vectorize", LoopHintAttr::Vectorize)
                  .Case("vectorize_width", LoopHintAttr::VectorizeWidth)
                  .Case("interleave", LoopHintAttr::Interleave)
+                 .Case("vectorize_predicate", LoopHintAttr::VectorizePredicate)
                  .Case("interleave_count", LoopHintAttr::InterleaveCount)
                  .Case("unroll", LoopHintAttr::Unroll)
                  .Case("unroll_count", LoopHintAttr::UnrollCount)
@@ -151,6 +152,7 @@
       State = LoopHintAttr::Numeric;
     } else if (Option == LoopHintAttr::Vectorize ||
                Option == LoopHintAttr::Interleave ||
+               Option == LoopHintAttr::VectorizePredicate ||
                Option == LoopHintAttr::Unroll ||
                Option == LoopHintAttr::Distribute ||
                Option == LoopHintAttr::PipelineDisabled) {
@@ -189,7 +191,8 @@
     const LoopHintAttr *StateAttr;
     const LoopHintAttr *NumericAttr;
   } HintAttrs[] = {{nullptr, nullptr}, {nullptr, nullptr}, {nullptr, nullptr},
-                   {nullptr, nullptr}, {nullptr, nullptr}, {nullptr, nullptr}};
+                   {nullptr, nullptr}, {nullptr, nullptr}, {nullptr, nullptr},
+                   {nullptr, nullptr}};
 
   for (const auto *I : Attrs) {
     const LoopHintAttr *LH = dyn_cast<LoopHintAttr>(I);
@@ -205,7 +208,8 @@
       Unroll,
       UnrollAndJam,
       Distribute,
-      Pipeline
+      Pipeline,
+      VectorizePredicate
     } Category;
     switch (Option) {
     case LoopHintAttr::Vectorize:
@@ -232,6 +236,9 @@
     case LoopHintAttr::PipelineInitiationInterval:
       Category = Pipeline;
       break;
+    case LoopHintAttr::VectorizePredicate:
+      Category = VectorizePredicate;
+      break;
     };
 
     assert(Category < sizeof(HintAttrs) / sizeof(HintAttrs[0]));
@@ -240,6 +247,7 @@
     if (Option == LoopHintAttr::Vectorize ||
         Option == LoopHintAttr::Interleave || Option == LoopHintAttr::Unroll ||
         Option == LoopHintAttr::UnrollAndJam ||
+        Option == LoopHintAttr::VectorizePredicate ||
         Option == LoopHintAttr::PipelineDisabled ||
         Option == LoopHintAttr::Distribute) {
       // Enable|Disable|AssumeSafety hint.  For example, vectorize(enable).