Add -unroll-runtime for unrolling loops with run-time trip counts.
Patch by Brendon Cahoon!
This extends the existing LoopUnroll and LoopUnrollPass. Brendon
measured no regressions in the llvm test suite with -unroll-runtime
enabled. This implementation works by using the existing loop
unrolling code to unroll the loop by a power-of-two (default 8). It
generates an if-then-else sequence of code prior to the loop to
execute the extra iterations before entering the unrolled loop.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146245 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Transforms/LoopUnroll/runtime-loop1.ll b/test/Transforms/LoopUnroll/runtime-loop1.ll
new file mode 100644
index 0000000..ad99b8c
--- /dev/null
+++ b/test/Transforms/LoopUnroll/runtime-loop1.ll
@@ -0,0 +1,30 @@
+; RUN: opt < %s -S -loop-unroll -unroll-runtime -unroll-count=4 | FileCheck %s
+
+; This tests that setting the unroll count works
+
+; CHECK: unr.cmp:
+; CHECK: for.body.unr:
+; CHECK: for.body:
+; CHECK: br i1 %exitcond.3, label %for.end.loopexit{{.*}}, label %for.body
+; CHECK-NOT: br i1 %exitcond.4, label %for.end.loopexit{{.*}}, label %for.body
+
+define i32 @test(i32* nocapture %a, i32 %n) nounwind uwtable readonly {
+entry:
+ %cmp1 = icmp eq i32 %n, 0
+ br i1 %cmp1, label %for.end, label %for.body
+
+for.body: ; preds = %for.body, %entry
+ %indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %entry ]
+ %sum.02 = phi i32 [ %add, %for.body ], [ 0, %entry ]
+ %arrayidx = getelementptr inbounds i32* %a, i64 %indvars.iv
+ %0 = load i32* %arrayidx, align 4
+ %add = add nsw i32 %0, %sum.02
+ %indvars.iv.next = add i64 %indvars.iv, 1
+ %lftr.wideiv = trunc i64 %indvars.iv.next to i32
+ %exitcond = icmp eq i32 %lftr.wideiv, %n
+ br i1 %exitcond, label %for.end, label %for.body
+
+for.end: ; preds = %for.body, %entry
+ %sum.0.lcssa = phi i32 [ 0, %entry ], [ %add, %for.body ]
+ ret i32 %sum.0.lcssa
+}