[PATCH] D94779: [Clang] Ensure vector predication pragma is ignored only when vectorization width is 1.

[Malhar via Phabricator via cfe-commits]

malharJ created this revision.
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This ensures that the Clang loop pragma vectorize_predicate([enable|disable]) is ignored
when vectorize_width(1) is also used, since that effectively disables vectorization.
For all other non-zero vectorization widths, the pragma is not ignored unless vectorization
is explicitly disabled using vectorize(disable)


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D94779

Files:
  clang/lib/CodeGen/CGLoopInfo.cpp
  clang/test/CodeGenCXX/pragma-loop-predicate.cpp


Index: clang/test/CodeGenCXX/pragma-loop-predicate.cpp
===================================================================
--- clang/test/CodeGenCXX/pragma-loop-predicate.cpp
+++ clang/test/CodeGenCXX/pragma-loop-predicate.cpp
@@ -58,6 +58,28 @@
     List[i] = i * 2;
 }
 
+// Check that vectorize_predicate is ignored when vectorization width is 1
+void test6(int *List, int Length) {
+// CHECK-LABEL: @{{.*}}test6{{.*}}(
+// CHECK: br label {{.*}}, !llvm.loop ![[LOOP6:.*]]
+
+#pragma clang loop vectorize_predicate(disable) vectorize_width(1)
+  for (int i = 0; i < Length; i++)
+    List[i] = i * 2;
+}
+
+
+// Check that vectorize_width(!=1) does not affect vectorize_predicate.
+void test7(int *List, int Length) {
+// CHECK-LABEL: @{{.*}}test7{{.*}}(
+// CHECK: br label {{.*}}, !llvm.loop ![[LOOP7:.*]]
+
+#pragma clang loop vectorize_predicate(disable) vectorize_width(4)
+  for (int i = 0; i < Length; i++)
+    List[i] = i * 2;
+}
+
+
 // CHECK:      ![[LOOP0]] = distinct !{![[LOOP0]], [[MP:![0-9]+]], [[GEN3:![0-9]+]]}
 // CHECK:      [[MP]] = !{!"llvm.loop.mustprogress"}
 // CHECK-NEXT: [[GEN3]] = !{!"llvm.loop.vectorize.enable", i1 true}
@@ -74,3 +96,8 @@
 // CHECK-NEXT: [[GEN10]] = !{!"llvm.loop.vectorize.width", i32 1}
 
 // CHECK-NEXT: ![[LOOP5]] = distinct !{![[LOOP5]], [[MP]], [[GEN10]]}
+
+// CHECK-NEXT: ![[LOOP6]] = distinct !{![[LOOP6]], [[MP]], [[GEN10]]}
+
+// CHECK-NEXT: ![[LOOP7]] = distinct !{![[LOOP7]], [[MP]], [[GEN8]], [[GEN11:![0-9]+]], [[GEN3]]}
+// CHECK-NEXT: [[GEN11]] = !{!"llvm.loop.vectorize.width", i32 4}
Index: clang/lib/CodeGen/CGLoopInfo.cpp
===================================================================
--- clang/lib/CodeGen/CGLoopInfo.cpp
+++ clang/lib/CodeGen/CGLoopInfo.cpp
@@ -249,11 +249,12 @@
   Args.push_back(nullptr);
   Args.append(LoopProperties.begin(), LoopProperties.end());
 
-  // Setting vectorize.predicate
+  // Setting vectorize.predicate when it has been specified and vectorization
+  // has not been disabled.
   bool IsVectorPredicateEnabled = false;
   if (Attrs.VectorizePredicateEnable != LoopAttributes::Unspecified &&
       Attrs.VectorizeEnable != LoopAttributes::Disable &&
-      Attrs.VectorizeWidth < 1) {
+      Attrs.VectorizeWidth != 1) {
 
     IsVectorPredicateEnabled =
         (Attrs.VectorizePredicateEnable == LoopAttributes::Enable);


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