[llvm] r306564 - [LoopUnroll] Fix bug in computeUnrollCount causing it to not honor MaxCount

[Geoff Berry via llvm-commits]

Author: gberry
Date: Wed Jun 28 10:01:15 2017
New Revision: 306564

URL: http://llvm.org/viewvc/llvm-project?rev=306564&view=rev
Log:
[LoopUnroll] Fix bug in computeUnrollCount causing it to not honor MaxCount

Reviewers: sanjoy, anna, reames, apilipenko, igor-laevsky, mkuper

Subscribers: mcrosier, llvm-commits, mzolotukhin

Differential Revision: https://reviews.llvm.org/D34532

Added:
    llvm/trunk/test/Transforms/LoopUnroll/unroll-maxcount.ll
Modified:
    llvm/trunk/lib/Transforms/Scalar/LoopUnrollPass.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/LoopUnrollPass.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopUnrollPass.cpp?rev=306564&r1=306563&r2=306564&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopUnrollPass.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoopUnrollPass.cpp Wed Jun 28 10:01:15 2017
@@ -836,6 +836,8 @@ static bool computeUnrollCount(
     } else {
       UP.Count = TripCount;
     }
+    if (UP.Count > UP.MaxCount)
+      UP.Count = UP.MaxCount;
     if ((PragmaFullUnroll || PragmaEnableUnroll) && TripCount &&
         UP.Count != TripCount)
       ORE->emit(

Added: llvm/trunk/test/Transforms/LoopUnroll/unroll-maxcount.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopUnroll/unroll-maxcount.ll?rev=306564&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/LoopUnroll/unroll-maxcount.ll (added)
+++ llvm/trunk/test/Transforms/LoopUnroll/unroll-maxcount.ll Wed Jun 28 10:01:15 2017
@@ -0,0 +1,31 @@
+; RUN: opt < %s -S -loop-unroll -unroll-allow-partial -unroll-max-count=1 | FileCheck %s
+; Checks that unroll MaxCount is honored.
+;
+; CHECK-LABEL: @foo(
+; CHECK-LABEL: for.body:
+; CHECK-NEXT: phi
+; CHECK-NEXT: getelementptr
+; CHECK-NEXT: load
+; CHECK-NEXT: add
+; CHECK-NEXT: store
+; CHECK-NEXT: add
+; CHECK-NEXT: icmp
+; CHECK-NEXT: br
+define void @foo(i32* nocapture %a) {
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %entry
+  %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
+  %arrayidx = getelementptr inbounds i32, i32* %a, i64 %indvars.iv
+  %0 = load i32, i32* %arrayidx, align 4
+  %inc = add nsw i32 %0, 1
+  store i32 %inc, i32* %arrayidx, align 4
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+  %exitcond = icmp eq i64 %indvars.iv.next, 1024
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.body
+  ret void
+}
+