[PATCH] D18670: LoopUnroll: some small fixes/tweaks to make it more useful for partial unrolling

[escha via llvm-commits]

escha updated this revision to Diff 52428.
escha added a comment.

Adding full context.


Repository:
  rL LLVM

http://reviews.llvm.org/D18670

Files:
  include/llvm/Analysis/TargetTransformInfo.h
  lib/Transforms/Scalar/LoopUnrollPass.cpp

Index: lib/Transforms/Scalar/LoopUnrollPass.cpp
===================================================================
--- lib/Transforms/Scalar/LoopUnrollPass.cpp
+++ lib/Transforms/Scalar/LoopUnrollPass.cpp
@@ -107,6 +107,7 @@
   UP.PartialOptSizeThreshold = UP.OptSizeThreshold;
   UP.Count = 0;
   UP.MaxCount = UINT_MAX;
+  UP.FullUnrollMaxCount = UINT_MAX;
   UP.Partial = false;
   UP.Runtime = false;
   UP.AllowExpensiveTripCount = false;
@@ -566,6 +567,7 @@
     Count = TripCount == 0 ? DefaultUnrollRuntimeCount : TripCount;
   if (TripCount && Count > TripCount)
     Count = TripCount;
+  Count = std::min(Count, UP.FullUnrollMaxCount);
 
   unsigned NumInlineCandidates;
   bool NotDuplicatable;
@@ -633,10 +635,12 @@
                    << "-unroll-allow-partial not given\n");
       return false;
     }
-    if (UP.PartialThreshold != NoThreshold &&
-        UnrolledSize > UP.PartialThreshold) {
+    if (UP.PartialThreshold != NoThreshold) {
       // Reduce unroll count to be modulo of TripCount for partial unrolling.
-      Count = (std::max(UP.PartialThreshold, 3u) - 2) / (LoopSize - 2);
+      if (UnrolledSize > UP.PartialThreshold)
+        Count = (std::max(UP.PartialThreshold, 3u) - 2) / (LoopSize - 2);
+      if (Count > UP.MaxCount)
+        Count = UP.MaxCount;
       while (Count != 0 && TripCount % Count != 0)
         Count--;
     }
Index: include/llvm/Analysis/TargetTransformInfo.h
===================================================================
--- include/llvm/Analysis/TargetTransformInfo.h
+++ include/llvm/Analysis/TargetTransformInfo.h
@@ -260,6 +260,10 @@
     // (set to UINT_MAX to disable). This does not apply in cases where the
     // loop is being fully unrolled.
     unsigned MaxCount;
+    /// Set the maximum unrolling factor for full unrolling. Like MaxCount, but
+    /// applies even if full unrolling is selected. This allows a target to fall
+    /// back to Partial unrolling if full unrolling is above FullUnrollMaxCount.
+    unsigned FullUnrollMaxCount;
     /// Allow partial unrolling (unrolling of loops to expand the size of the
     /// loop body, not only to eliminate small constant-trip-count loops).
     bool Partial;


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D18670.52428.patch
Type: text/x-patch
Size: 2201 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20160401/4bca128c/attachment.bin>