[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
llvm-svn: 306564
diff --git a/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp b/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
index 8bdbb3f..530a684 100644
--- a/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
@@ -836,6 +836,8 @@
} else {
UP.Count = TripCount;
}
+ if (UP.Count > UP.MaxCount)
+ UP.Count = UP.MaxCount;
if ((PragmaFullUnroll || PragmaEnableUnroll) && TripCount &&
UP.Count != TripCount)
ORE->emit(
diff --git a/llvm/test/Transforms/LoopUnroll/unroll-maxcount.ll b/llvm/test/Transforms/LoopUnroll/unroll-maxcount.ll
new file mode 100644
index 0000000..4cbd757
--- /dev/null
+++ b/llvm/test/Transforms/LoopUnroll/unroll-maxcount.ll
@@ -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
+}
+
