Enable runtime unrolling with unroll pragma metadata
Enable runtime unrolling for loops with unroll count metadata ("#pragma unroll N")
and a runtime trip count. Also, do not unroll loops with unroll full metadata if the
loop has a runtime loop count. Previously, such loops would be unrolled with a
very large threshold (pragma-unroll-threshold) if runtime unrolled happened to be
enabled resulting in a very large (and likely unwise) unroll factor.
llvm-svn: 242047
diff --git a/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp b/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
index 9e7558d..d78db6c 100644
--- a/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
@@ -840,8 +840,10 @@
// Reduce count based on the type of unrolling and the threshold values.
unsigned OriginalCount = Count;
- bool AllowRuntime = UserRuntime ? CurrentRuntime : UP.Runtime;
- if (HasRuntimeUnrollDisablePragma(L)) {
+ bool AllowRuntime =
+ (PragmaCount > 0) || (UserRuntime ? CurrentRuntime : UP.Runtime);
+ // Don't unroll a runtime trip count loop with unroll full pragma.
+ if (HasRuntimeUnrollDisablePragma(L) || PragmaFullUnroll) {
AllowRuntime = false;
}
if (Unrolling == Partial) {