Add transformation:

 xor (or (icmp, icmp), true) -> and(icmp, icmp)

This is possible because of De Morgan's law.

llvm-svn: 61537

1 files changed, 11 insertions, 0 deletions

diff --git a/llvm/test/Transforms/InstCombine/xor-demorgans.ll b/llvm/test/Transforms/InstCombine/xor-demorgans.ll
new file mode 100644
index 00000000000..763794befcb
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/xor-demorgans.ll
@@ -0,0 +1,11 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep {= or}
+; PR3266
+
+define i1 @foo(i32 %x, i32 %y) nounwind {
+.summary:
+       %0 = icmp sgt i32 %x, 4         ; <i1> [#uses=1]
+       %1 = icmp sgt i32 %y, 0         ; <i1> [#uses=1]
+       %.demorgan = or i1 %1, %0               ; <i1> [#uses=1]
+       %2 = xor i1 %.demorgan, true            ; <i1> [#uses=1]
+       ret i1 %2
+}