rdar://12329730 (defect 2)

Enhancement to InstCombine. Try to catch this opportunity:
  
 ---------------------------------------------------------------
 ((X^C1) >> C2) ^ C3  => (X>>C2) ^ ((C1>>C2)^C3)
  where the subexpression "X ^ C1" has more than one uses, and
  "(X^C1) >> C2" has single use. 
 ---------------------------------------------------------------- 

 Reviewed by Nadav (with minor change per his request).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168615 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 15 insertions, 0 deletions

diff --git a/test/Transforms/InstCombine/xor2.ll b/test/Transforms/InstCombine/xor2.ll
index 89f00bd684..3c99246796 100644
--- a/test/Transforms/InstCombine/xor2.ll
+++ b/test/Transforms/InstCombine/xor2.ll
@@ -51,3 +51,18 @@ define i32 @test4(i32 %A, i32 %B) {
 ; CHECK: %1 = ashr i32 %A, %B
 ; CHECK: ret i32 %1
 }
+
+; defect-2 in rdar://12329730
+; (X^C1) >> C2) ^ C3 -> (X>>C2) ^ ((C1>>C2)^C3)
+;   where the "X" has more than one use
+define i32 @test5(i32 %val1) {
+test5:
+  %xor = xor i32 %val1, 1234
+  %shr = lshr i32 %xor, 8
+  %xor1 = xor i32 %shr, 1
+  %add = add i32 %xor1, %xor
+  ret i32 %add
+; CHECK: @test5
+; CHECK: lshr i32 %val1, 8
+; CHECK: ret
+}