From 535efab2e533f98a96df31b116b5861b5e29d32d Mon Sep 17 00:00:00 2001
From: Sjoerd Meijer <sjoerd.meijer@arm.com>
Date: Thu, 15 Aug 2019 06:24:40 +0000
Subject: [PATCH] [Clang] Pragma vectorize_predicate implies vectorize

New pragma "vectorize_predicate(enable)" now implies "vectorize(enable)",
and it is ignored when vectorization is disabled with e.g.
"vectorize(disable) vectorize_predicate(enable)".

Differential Revision: https://reviews.llvm.org/D65776

llvm-svn: 368970
---
 clang/lib/CodeGen/CGLoopInfo.cpp                | 21 +++++++++----
 clang/test/CodeGenCXX/pragma-loop-predicate.cpp | 41 +++++++++++++++++++++++++
 2 files changed, 56 insertions(+), 6 deletions(-)

diff --git a/clang/lib/CodeGen/CGLoopInfo.cpp b/clang/lib/CodeGen/CGLoopInfo.cpp
index 8e4a0a2..c51efdc 100644
--- a/clang/lib/CodeGen/CGLoopInfo.cpp
+++ b/clang/lib/CodeGen/CGLoopInfo.cpp
@@ -253,12 +253,18 @@ LoopInfo::createLoopVectorizeMetadata(const LoopAttributes &Attrs,
   Args.append(LoopProperties.begin(), LoopProperties.end());
 
   // Setting vectorize.predicate
-  if (Attrs.VectorizePredicateEnable != LoopAttributes::Unspecified) {
+  bool IsVectorPredicateEnabled = false;
+  if (Attrs.VectorizePredicateEnable != LoopAttributes::Unspecified &&
+      Attrs.VectorizeEnable != LoopAttributes::Disable &&
+      Attrs.VectorizeWidth < 1) {
+
+    IsVectorPredicateEnabled =
+        (Attrs.VectorizePredicateEnable == LoopAttributes::Enable);
+
     Metadata *Vals[] = {
         MDString::get(Ctx, "llvm.loop.vectorize.predicate.enable"),
-        ConstantAsMetadata::get(ConstantInt::get(
-            llvm::Type::getInt1Ty(Ctx),
-            (Attrs.VectorizePredicateEnable == LoopAttributes::Enable)))};
+        ConstantAsMetadata::get(ConstantInt::get(llvm::Type::getInt1Ty(Ctx),
+                                                 IsVectorPredicateEnabled))};
     Args.push_back(MDNode::get(Ctx, Vals));
   }
 
@@ -281,12 +287,15 @@ LoopInfo::createLoopVectorizeMetadata(const LoopAttributes &Attrs,
   }
 
   // Setting vectorize.enable
-  if (Attrs.VectorizeEnable != LoopAttributes::Unspecified) {
+  if (Attrs.VectorizeEnable != LoopAttributes::Unspecified ||
+      IsVectorPredicateEnabled) {
     Metadata *Vals[] = {
         MDString::get(Ctx, "llvm.loop.vectorize.enable"),
         ConstantAsMetadata::get(ConstantInt::get(
             llvm::Type::getInt1Ty(Ctx),
-            (Attrs.VectorizeEnable == LoopAttributes::Enable)))};
+            IsVectorPredicateEnabled
+                ? true
+                : (Attrs.VectorizeEnable == LoopAttributes::Enable)))};
     Args.push_back(MDNode::get(Ctx, Vals));
   }
 
diff --git a/clang/test/CodeGenCXX/pragma-loop-predicate.cpp b/clang/test/CodeGenCXX/pragma-loop-predicate.cpp
index 74aed5d..ec2161d 100644
--- a/clang/test/CodeGenCXX/pragma-loop-predicate.cpp
+++ b/clang/test/CodeGenCXX/pragma-loop-predicate.cpp
@@ -27,9 +27,50 @@ void test2(int *List, int Length) {
     List[i] = i * 2;
 }
 
+// vectorize_predicate(enable) implies vectorize(enable)
+void test3(int *List, int Length) {
+// CHECK-LABEL: @{{.*}}test3{{.*}}(
+// CHECK:       br label {{.*}}, !llvm.loop ![[LOOP3:.*]]
+
+  #pragma clang loop vectorize_predicate(enable)
+  for (int i = 0; i < Length; i++)
+    List[i] = i * 2;
+}
+
+// Check that disabling vectorization means a vectorization width of 1, and
+// also that vectorization_predicate isn't enabled.
+void test4(int *List, int Length) {
+// CHECK-LABEL: @{{.*}}test4{{.*}}(
+// CHECK: br label {{.*}}, !llvm.loop ![[LOOP4:.*]]
+
+  #pragma clang loop vectorize(disable)
+  for (int i = 0; i < Length; i++)
+    List[i] = i * 2;
+}
+
+// Check that vectorize and vectorize_predicate are disabled.
+void test5(int *List, int Length) {
+// CHECK-LABEL: @{{.*}}test5{{.*}}(
+// CHECK: br label {{.*}}, !llvm.loop ![[LOOP5:.*]]
+
+  #pragma clang loop vectorize(disable) vectorize_predicate(enable)
+  for (int i = 0; i < Length; i++)
+    List[i] = i * 2;
+}
+
+
 // CHECK:      ![[LOOP0]] = distinct !{![[LOOP0]], !3}
 // CHECK-NEXT: !3 = !{!"llvm.loop.vectorize.enable", i1 true}
+
 // CHECK-NEXT: ![[LOOP1]] = distinct !{![[LOOP1]], !5, !3}
 // CHECK-NEXT: !5 = !{!"llvm.loop.vectorize.predicate.enable", i1 true}
+
 // CHECK-NEXT: ![[LOOP2]] = distinct !{![[LOOP2]], !7, !3}
 // CHECK-NEXT: !7 = !{!"llvm.loop.vectorize.predicate.enable", i1 false}
+
+// CHECK-NEXT: ![[LOOP3]] = distinct !{![[LOOP3]], !5, !3}
+
+// CHECK-NEXT: ![[LOOP4]] = distinct !{![[LOOP4]], !10}
+// CHECK-NEXT: !10 = !{!"llvm.loop.vectorize.width", i32 1}
+
+// CHECK-NEXT: ![[LOOP5]] = distinct !{![[LOOP5]], !10}
-- 
2.7.4