[InstCombine] Add test for shifts from or chains

Author: davemgreen

llvm/test/Transforms/InstCombine/icmp-of-or-x.ll

@@ -409,3 +409,122 @@ define i1 @PR38139(i8 %arg) {
   %r = icmp ne i8 %masked, %arg
   ret i1 %r
 }
+
+define i1 @remove_shift_nuw_ab(i8 %a, i8 %b, i8 %s) {
+; CHECK-LABEL: @remove_shift_nuw_ab(
+; CHECK-NEXT:    [[T:%.*]] = shl nuw i8 [[A:%.*]], [[S:%.*]]
+; CHECK-NEXT:    [[OR:%.*]] = or i8 [[T]], [[B:%.*]]
+; CHECK-NEXT:    [[IC:%.*]] = icmp eq i8 [[OR]], 0
+; CHECK-NEXT:    ret i1 [[IC]]
+;
+  %t = shl nuw i8 %a, %s
+  %or = or i8 %t, %b
+  %ic = icmp eq i8 %or, 0
+  ret i1 %ic
+}
+
+define i1 @remove_shift_nuw_ba(i8 %a, i8 %b, i8 %s) {
+; CHECK-LABEL: @remove_shift_nuw_ba(
+; CHECK-NEXT:    [[T:%.*]] = shl nuw i8 [[A:%.*]], [[S:%.*]]
+; CHECK-NEXT:    [[OR:%.*]] = or i8 [[B:%.*]], [[T]]
+; CHECK-NEXT:    [[IC:%.*]] = icmp eq i8 [[OR]], 0
+; CHECK-NEXT:    ret i1 [[IC]]
+;
+  %t = shl nuw i8 %a, %s
+  %or = or i8 %b, %t
+  %ic = icmp eq i8 %or, 0
+  ret i1 %ic
+}
+
+define i1 @remove_shift_nsw(i8 %a, i8 %b, i8 %s) {
+; CHECK-LABEL: @remove_shift_nsw(
+; CHECK-NEXT:    [[T:%.*]] = shl nsw i8 [[A:%.*]], [[S:%.*]]
+; CHECK-NEXT:    [[OR:%.*]] = or i8 [[T]], [[B:%.*]]
+; CHECK-NEXT:    [[IC:%.*]] = icmp eq i8 [[OR]], 0
+; CHECK-NEXT:    ret i1 [[IC]]
+;
+  %t = shl nsw i8 %a, %s
+  %or = or i8 %t, %b
+  %ic = icmp eq i8 %or, 0
+  ret i1 %ic
+}
+
+define i1 @remove_shift_nuw_ne(i8 %a, i8 %b, i8 %s) {
+; CHECK-LABEL: @remove_shift_nuw_ne(
+; CHECK-NEXT:    [[T:%.*]] = shl nuw i8 [[A:%.*]], [[S:%.*]]
+; CHECK-NEXT:    [[OR:%.*]] = or i8 [[T]], [[B:%.*]]
+; CHECK-NEXT:    [[IC:%.*]] = icmp eq i8 [[OR]], 0
+; CHECK-NEXT:    ret i1 [[IC]]
+;
+  %t = shl nuw i8 %a, %s
+  %or = or i8 %t, %b
+  %ic = icmp eq i8 %or, 0
+  ret i1 %ic
+}
+
+define i1 @remove_shift_nsw_ne(i8 %a, i8 %b, i8 %s) {
+; CHECK-LABEL: @remove_shift_nsw_ne(
+; CHECK-NEXT:    [[T:%.*]] = shl nsw i8 [[A:%.*]], [[S:%.*]]
+; CHECK-NEXT:    [[OR:%.*]] = or i8 [[T]], [[B:%.*]]
+; CHECK-NEXT:    [[IC:%.*]] = icmp eq i8 [[OR]], 0
+; CHECK-NEXT:    ret i1 [[IC]]
+;
+  %t = shl nsw i8 %a, %s
+  %or = or i8 %t, %b
+  %ic = icmp eq i8 %or, 0
+  ret i1 %ic
+}
+
+define i1 @remove_shift_wraps(i8 %a, i8 %b, i8 %s) {
+; CHECK-LABEL: @remove_shift_wraps(
+; CHECK-NEXT:    [[T:%.*]] = shl i8 [[A:%.*]], [[S:%.*]]
+; CHECK-NEXT:    [[OR:%.*]] = or i8 [[T]], [[B:%.*]]
+; CHECK-NEXT:    [[IC:%.*]] = icmp eq i8 [[OR]], 0
+; CHECK-NEXT:    ret i1 [[IC]]
+;
+  %t = shl i8 %a, %s
+  %or = or i8 %t, %b
+  %ic = icmp eq i8 %or, 0
+  ret i1 %ic
+}
+
+define i1 @remove_shift_chain_d(i8 %a, i8 %b, i8 %c, i8 %d, i8 %s) {
+; CHECK-LABEL: @remove_shift_chain_d(
+; CHECK-NEXT:    [[DT:%.*]] = shl nuw i8 [[D:%.*]], [[S:%.*]]
+; CHECK-NEXT:    [[OR1:%.*]] = or i8 [[A:%.*]], [[B:%.*]]
+; CHECK-NEXT:    [[OR2:%.*]] = or i8 [[C:%.*]], [[DT]]
+; CHECK-NEXT:    [[OR:%.*]] = or i8 [[OR1]], [[OR2]]
+; CHECK-NEXT:    [[IC:%.*]] = icmp eq i8 [[OR]], 0
+; CHECK-NEXT:    ret i1 [[IC]]
+;
+  %dt = shl nuw i8 %d, %s
+  %or1 = or i8 %a, %b
+  %or2 = or i8 %c, %dt
+  %or = or i8 %or1, %or2
+  %ic = icmp eq i8 %or, 0
+  ret i1 %ic
+}
+
+define i1 @remove_shift_chain_abcd(i8 %a, i8 %b, i8 %c, i8 %d, i8 %s) {
+; CHECK-LABEL: @remove_shift_chain_abcd(
+; CHECK-NEXT:    [[AT:%.*]] = shl nuw i8 [[A:%.*]], [[S:%.*]]
+; CHECK-NEXT:    [[BT:%.*]] = shl nuw i8 [[B:%.*]], 2
+; CHECK-NEXT:    [[CT:%.*]] = shl nuw i8 [[C:%.*]], 1
+; CHECK-NEXT:    [[DT:%.*]] = shl nuw i8 [[D:%.*]], [[S]]
+; CHECK-NEXT:    [[OR1:%.*]] = or i8 [[AT]], [[BT]]
+; CHECK-NEXT:    [[OR2:%.*]] = or i8 [[CT]], [[DT]]
+; CHECK-NEXT:    [[OR:%.*]] = or i8 [[OR1]], [[OR2]]
+; CHECK-NEXT:    [[IC:%.*]] = icmp eq i8 [[OR]], 0
+; CHECK-NEXT:    ret i1 [[IC]]
+;
+  %at = shl nuw i8 %a, %s
+  %bt = shl nuw i8 %b, 2
+  %ct = shl nuw i8 %c, 1
+  %dt = shl nuw i8 %d, %s
+  %or1 = or i8 %at, %bt
+  %or2 = or i8 %ct, %dt
+  %or = or i8 %or1, %or2
+  %ic = icmp eq i8 %or, 0
+  ret i1 %ic
+}
+