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-loop3.ll b/test/Transforms/LoopUnroll/runtime-loop3.ll
new file mode 100644
index 0000000..55cf223
--- /dev/null
+++ b/test/Transforms/LoopUnroll/runtime-loop3.ll
@@ -0,0 +1,44 @@
+; RUN: opt < %s -disable-output -stats -loop-unroll -unroll-runtime -unroll-threshold=400 -info-output-file - | FileCheck %s --check-prefix=STATS
+
+; Test that nested loops can be unrolled. We need to increase threshold to do it
+
+; STATS: 2 loop-unroll - Number of loops unrolled (completely or otherwise)
+
+define i32 @nested(i32* nocapture %a, i32 %n, i32 %m) nounwind uwtable readonly {
+entry:
+ %cmp11 = icmp sgt i32 %n, 0
+ br i1 %cmp11, label %for.cond1.preheader.lr.ph, label %for.end7
+
+for.cond1.preheader.lr.ph: ; preds = %entry
+ %cmp28 = icmp sgt i32 %m, 0
+ br label %for.cond1.preheader
+
+for.cond1.preheader: ; preds = %for.inc5, %for.cond1.preheader.lr.ph
+ %indvars.iv16 = phi i64 [ 0, %for.cond1.preheader.lr.ph ], [ %indvars.iv.next17, %for.inc5 ]
+ %sum.012 = phi i32 [ 0, %for.cond1.preheader.lr.ph ], [ %sum.1.lcssa, %for.inc5 ]
+ br i1 %cmp28, label %for.body3, label %for.inc5
+
+for.body3: ; preds = %for.cond1.preheader, %for.body3
+ %indvars.iv = phi i64 [ %indvars.iv.next, %for.body3 ], [ 0, %for.cond1.preheader ]
+ %sum.19 = phi i32 [ %add4, %for.body3 ], [ %sum.012, %for.cond1.preheader ]
+ %0 = add nsw i64 %indvars.iv, %indvars.iv16
+ %arrayidx = getelementptr inbounds i32* %a, i64 %0
+ %1 = load i32* %arrayidx, align 4
+ %add4 = add nsw i32 %1, %sum.19
+ %indvars.iv.next = add i64 %indvars.iv, 1
+ %lftr.wideiv = trunc i64 %indvars.iv.next to i32
+ %exitcond = icmp eq i32 %lftr.wideiv, %m
+ br i1 %exitcond, label %for.inc5, label %for.body3
+
+for.inc5: ; preds = %for.body3, %for.cond1.preheader
+ %sum.1.lcssa = phi i32 [ %sum.012, %for.cond1.preheader ], [ %add4, %for.body3 ]
+ %indvars.iv.next17 = add i64 %indvars.iv16, 1
+ %lftr.wideiv18 = trunc i64 %indvars.iv.next17 to i32
+ %exitcond19 = icmp eq i32 %lftr.wideiv18, %n
+ br i1 %exitcond19, label %for.end7, label %for.cond1.preheader
+
+for.end7: ; preds = %for.inc5, %entry
+ %sum.0.lcssa = phi i32 [ 0, %entry ], [ %sum.1.lcssa, %for.inc5 ]
+ ret i32 %sum.0.lcssa
+}
+