Fix a couple of logic bugs in TargetLowering::SimplifyDemandedBits. PR11514.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146219 91177308-0d34-0410-b5e6-96231b3b80d8

test/CodeGen/PowerPC/2011-12-08-DemandedBitsMiscompile.ll

@@ -0,0 +1,16 @@
+; RUN: llc < %s -mtriple=powerpc64-unknown-linux-gnu -mcpu=g4 | FileCheck %s
+
+define void @test(i32* nocapture %x, i64* %xx, i32* %yp) nounwind uwtable ssp {
+entry:
+  %yy = load i32* %yp
+  %y = add i32 %yy, 1
+  %z = zext i32 %y to i64
+  %z2 = shl i64 %z, 32 
+  store i64 %z2, i64* %xx, align 4
+  ret void
+
+; CHECK: test:
+; CHECK: sldi {{.*}}, {{.*}}, 32
+; Note: it's okay if someday CodeGen gets smart enough to optimize out
+; the shift.
+}