[LoopPeeling] Fix condition for phi-eliminating peeling
When peeling loops basing on phis becoming invariants, we make a wrong loop size check.
UP.Threshold should be compared against the total numbers of instructions after the transformation,
which is equal to 2 * LoopSize in case of peeling one iteration.
We should also check that the maximum allowed number of peeled iterations is not zero.
Reviewers: sanjoy, anna, reames, mkuper
Reviewed By: mkuper
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D31753
llvm-svn: 300441
diff --git a/llvm/test/Transforms/LoopUnroll/peel-loop-negative.ll b/llvm/test/Transforms/LoopUnroll/peel-loop-negative.ll
new file mode 100644
index 0000000..eab609a
--- /dev/null
+++ b/llvm/test/Transforms/LoopUnroll/peel-loop-negative.ll
@@ -0,0 +1,28 @@
+; RUN: opt < %s -S -loop-unroll -unroll-threshold=800 -unroll-peel-max-count=0 | FileCheck %s
+
+; We should not peel this loop even though we can, because the max count is set
+; to zero.
+define i32 @invariant_backedge_neg_1(i32 %a, i32 %b) {
+; CHECK-LABEL: @invariant_backedge_neg_1
+; CHECK-NOT loop.peel{{.*}}:
+; CHECK: loop:
+; CHECK: %i = phi
+; CHECK: %sum = phi
+; CHECK: %plus = phi
+entry:
+ br label %loop
+
+loop:
+ %i = phi i32 [ 0, %entry ], [ %inc, %loop ]
+ %sum = phi i32 [ 0, %entry ], [ %incsum, %loop ]
+ %plus = phi i32 [ %a, %entry ], [ %b, %loop ]
+
+ %incsum = add i32 %sum, %plus
+ %inc = add i32 %i, 1
+ %cmp = icmp slt i32 %i, 1000
+
+ br i1 %cmp, label %loop, label %exit
+
+exit:
+ ret i32 %sum
+}
diff --git a/llvm/test/Transforms/LoopUnroll/peel-loop-not-forced.ll b/llvm/test/Transforms/LoopUnroll/peel-loop-not-forced.ll
index 3dcac87..c3cbbf1 100644
--- a/llvm/test/Transforms/LoopUnroll/peel-loop-not-forced.ll
+++ b/llvm/test/Transforms/LoopUnroll/peel-loop-not-forced.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -S -loop-unroll -unroll-threshold=4 | FileCheck %s
+; RUN: opt < %s -S -loop-unroll -unroll-threshold=8 | FileCheck %s
define i32 @invariant_backedge_1(i32 %a, i32 %b) {
; CHECK-LABEL: @invariant_backedge_1