InstCombine: Add a bunch of combines of the form x | (y ^ z).

We usually catch this kind of optimization through InstSimplify's distributive
magic, but or doesn't distribute over xor in general.

"A | ~(A | B) -> A | ~B" hits 24 times on gcc.c.

llvm-svn: 126081

1 files changed, 94 insertions, 0 deletions

diff --git a/llvm/test/Transforms/InstCombine/or-xor.ll b/llvm/test/Transforms/InstCombine/or-xor.ll
new file mode 100644
index 00000000000..f496dd48c40
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/or-xor.ll
@@ -0,0 +1,94 @@
+; RUN: opt -S -instcombine < %s | FileCheck %s
+
+define i32 @test1(i32 %x, i32 %y) nounwind {
+  %or = or i32 %x, %y
+  %not = xor i32 %or, -1
+  %z = or i32 %x, %not
+  ret i32 %z
+; CHECK: @test1
+; CHECK-NEXT: %y.not = xor i32 %y, -1
+; CHECK-NEXT: %z = or i32 %y.not, %x
+; CHECK-NEXT: ret i32 %z
+}
+
+define i32 @test2(i32 %x, i32 %y) nounwind {
+  %or = or i32 %x, %y
+  %not = xor i32 %or, -1
+  %z = or i32 %y, %not
+  ret i32 %z
+; CHECK: @test2
+; CHECK-NEXT: %x.not = xor i32 %x, -1
+; CHECK-NEXT: %z = or i32 %x.not, %y
+; CHECK-NEXT: ret i32 %z
+}
+
+define i32 @test3(i32 %x, i32 %y) nounwind {
+  %xor = xor i32 %x, %y
+  %not = xor i32 %xor, -1
+  %z = or i32 %x, %not
+  ret i32 %z
+; CHECK: @test3
+; CHECK-NEXT: %y.not = xor i32 %y, -1
+; CHECK-NEXT: %z = or i32 %y.not, %x
+; CHECK-NEXT: ret i32 %z
+}
+
+define i32 @test4(i32 %x, i32 %y) nounwind {
+  %xor = xor i32 %x, %y
+  %not = xor i32 %xor, -1
+  %z = or i32 %y, %not
+  ret i32 %z
+; CHECK: @test4
+; CHECK-NEXT: %x.not = xor i32 %x, -1
+; CHECK-NEXT: %z = or i32 %x.not, %y
+; CHECK-NEXT: ret i32 %z
+}
+
+define i32 @test5(i32 %x, i32 %y) nounwind {
+  %and = and i32 %x, %y
+  %not = xor i32 %and, -1
+  %z = or i32 %x, %not
+  ret i32 %z
+; CHECK: @test5
+; CHECK-NEXT: ret i32 -1
+}
+
+define i32 @test6(i32 %x, i32 %y) nounwind {
+  %and = and i32 %x, %y
+  %not = xor i32 %and, -1
+  %z = or i32 %y, %not
+  ret i32 %z
+; CHECK: @test6
+; CHECK-NEXT: ret i32 -1
+}
+
+define i32 @test7(i32 %x, i32 %y) nounwind {
+  %xor = xor i32 %x, %y
+  %z = or i32 %y, %xor
+  ret i32 %z
+; CHECK: @test7
+; CHECK-NEXT: %z = or i32 %x, %y
+; CHECK-NEXT: ret i32 %z
+}
+
+define i32 @test8(i32 %x, i32 %y) nounwind {
+  %not = xor i32 %y, -1
+  %xor = xor i32 %x, %not
+  %z = or i32 %y, %xor
+  ret i32 %z
+; CHECK: @test8
+; CHECK-NEXT: %x.not = xor i32 %x, -1
+; CHECK-NEXT: %z = or i32 %x.not, %y
+; CHECK-NEXT: ret i32 %z
+}
+
+define i32 @test9(i32 %x, i32 %y) nounwind {
+  %not = xor i32 %x, -1
+  %xor = xor i32 %not, %y
+  %z = or i32 %x, %xor
+  ret i32 %z
+; CHECK: @test9
+; CHECK-NEXT: %y.not = xor i32 %y, -1
+; CHECK-NEXT: %z = or i32 %y.not, %x
+; CHECK-NEXT: ret i32 %z
+}