We do want to allow LoadPRE to perform LICM-like transformations: we already consider PHI nodes to be negligible for

code size (making this transform code size neutral), and it allows us to hoist values out of loops, which is always
a good thing.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@115205 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 39 insertions, 0 deletions

diff --git a/test/Transforms/GVN/load-pre-licm.ll b/test/Transforms/GVN/load-pre-licm.ll
new file mode 100644
index 0000000..bbcc622
--- /dev/null
+++ b/test/Transforms/GVN/load-pre-licm.ll
@@ -0,0 +1,39 @@
+; RUN: opt -S -gvn < %s | FileCheck %s
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128-n8:16:32"
+target triple = "i386-apple-darwin11.0.0"
+
+@sortlist = external global [5001 x i32], align 4
+
+define void @Bubble() nounwind noinline {
+; CHECK: entry:
+; CHECK-NEXT: %tmp7.pre = load i32
+entry:
+  br label %while.body5
+
+; CHECK: while.body5:
+; CHECK: %tmp7 = phi i32
+; CHECK-NOT: %tmp7 = load i32
+while.body5:
+  %indvar = phi i32 [ 0, %entry ], [ %tmp6, %if.end ]
+  %tmp5 = add i32 %indvar, 2
+  %arrayidx9 = getelementptr [5001 x i32]* @sortlist, i32 0, i32 %tmp5
+  %tmp6 = add i32 %indvar, 1
+  %arrayidx = getelementptr [5001 x i32]* @sortlist, i32 0, i32 %tmp6
+  %tmp7 = load i32* %arrayidx, align 4
+  %tmp10 = load i32* %arrayidx9, align 4
+  %cmp11 = icmp sgt i32 %tmp7, %tmp10
+  br i1 %cmp11, label %if.then, label %if.end
+
+; CHECK: if.then:
+if.then:
+  store i32 %tmp10, i32* %arrayidx, align 4
+  store i32 %tmp7, i32* %arrayidx9, align 4
+  br label %if.end
+
+if.end:
+  %exitcond = icmp eq i32 %tmp6, 100
+  br i1 %exitcond, label %while.end.loopexit, label %while.body5
+
+while.end.loopexit:
+  ret void
+}