Instcombine's ShrinkDemandedConstant may strip bits out of constants,

obscuring what would otherwise be a low-bits mask.  Use ComputeMaskedBits
to compute what ShrinkDemandedConstant knew about to reconstruct a
low-bits mask value.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73540 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 14 insertions, 0 deletions

diff --git a/test/Transforms/IndVarSimplify/shrunk-constant.ll b/test/Transforms/IndVarSimplify/shrunk-constant.ll
new file mode 100644
index 0000000..f783b83
--- /dev/null
+++ b/test/Transforms/IndVarSimplify/shrunk-constant.ll
@@ -0,0 +1,14 @@
+; RUN: llvm-as < %s | opt -iv-users -analyze | grep store
+
+define fastcc void @foo() nounwind {
+entry:
+	br label %loop
+
+loop:
+	%i = phi i32 [ 0, %entry ], [ %t2, %loop ]
+	%t0 = add i32 %i, 9
+	%t1 = and i32 %t0, 9
+        store i32 %t1, i32* null
+	%t2 = add i32 %i, 8
+	br label %loop
+}