[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

1 files changed, 4 insertions, 0 deletions

diff --git a/clang/test/AST/ast-print-pragmas.cpp b/clang/test/AST/ast-print-pragmas.cpp
index a87be2a3403..7bd0b48d6e7 100644
--- a/clang/test/AST/ast-print-pragmas.cpp
+++ b/clang/test/AST/ast-print-pragmas.cpp
@@ -17,10 +17,12 @@ void test(int *List, int Length) {
 // CHECK: #pragma clang loop distribute(disable)
 // CHECK-NEXT: #pragma clang loop vectorize(enable)
 // CHECK-NEXT: #pragma clang loop interleave(disable)
+// CHECK-NEXT: #pragma clang loop vectorize_predicate(disable)
 
 #pragma clang loop distribute(disable)
 #pragma clang loop vectorize(enable)
 #pragma clang loop interleave(disable)
+#pragma clang loop vectorize_predicate(disable)
 // CHECK-NEXT: while (i - 1 < Length)
   while (i - 1 < Length) {
     List[i] = i * 2;
@@ -30,10 +32,12 @@ void test(int *List, int Length) {
 // CHECK: #pragma clang loop distribute(enable)
 // CHECK-NEXT: #pragma clang loop vectorize(disable)
 // CHECK-NEXT: #pragma clang loop interleave(enable)
+// CHECK-NEXT: #pragma clang loop vectorize_predicate(enable)
 
 #pragma clang loop distribute(enable)
 #pragma clang loop vectorize(disable)
 #pragma clang loop interleave(enable)
+#pragma clang loop vectorize_predicate(enable)
 // CHECK-NEXT: while (i - 2 < Length)
   while (i - 2 < Length) {
     List[i] = i * 2;