Teach InstructionSimplify to fold (A & B) & A -> A & B and (A | B) | A -> A | B.

Reassociate does this but it doesn't catch all cases (e.g. if the operands are i1).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@113651 91177308-0d34-0410-b5e6-96231b3b80d8

test/Transforms/InstCombine/and2.ll

@@ -8,3 +8,21 @@ define i1 @test1(double %X, double %Y) {
         ret i1 %bothcond
 ; CHECK:  fcmp ord double %Y, %X
 }
+
+define i1 @test2(i1 %X, i1 %Y) {
+  %a = and i1 %X, %Y
+  %b = and i1 %a, %X
+  ret i1 %b
+; CHECK: @test2
+; CHECK-NEXT: and i1 %X, %Y
+; CHECK-NEXT: ret
+}
+
+define i32 @test3(i32 %X, i32 %Y) {
+  %a = and i32 %X, %Y
+  %b = and i32 %Y, %a
+  ret i32 %b
+; CHECK: @test3
+; CHECK-NEXT: and i32 %X, %Y
+; CHECK-NEXT: ret
+}

test/Transforms/InstCombine/or.ll

@@ -350,3 +350,20 @@ define <4 x i32> @test32(<4 x i1> %and.i1352, <4 x i32> %vecinit6.i176, <4 x i32
 ; CHECK: or <4 x i32> %and.i, %and.i129
 }
 
+define i1 @test33(i1 %X, i1 %Y) {
+  %a = or i1 %X, %Y
+  %b = or i1 %a, %X
+  ret i1 %b
+; CHECK: @test33
+; CHECK-NEXT: or i1 %X, %Y
+; CHECK-NEXT: ret
+}
+
+define i32 @test34(i32 %X, i32 %Y) {
+  %a = or i32 %X, %Y
+  %b = or i32 %Y, %a
+  ret i32 %b
+; CHECK: @test34
+; CHECK-NEXT: or i32 %X, %Y
+; CHECK-NEXT: ret
+}