[ValueTracking] Add tests for inferring select arm bits from conditio…

…n; NFC

llvm/test/Analysis/ValueTracking/knownbits-select-from-cond.ll

@@ -0,0 +1,81 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -passes=instcombine -S < %s | FileCheck %s
+
+define i8 @select_condition_implies_highbits_op1(i8 %xx, i8 noundef %y) {
+; CHECK-LABEL: @select_condition_implies_highbits_op1(
+; CHECK-NEXT:    [[X:%.*]] = and i8 [[XX:%.*]], 15
+; CHECK-NEXT:    [[COND:%.*]] = icmp ult i8 [[Y:%.*]], 3
+; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[COND]], i8 [[Y]], i8 [[X]]
+; CHECK-NEXT:    [[R:%.*]] = add i8 [[SEL]], 32
+; CHECK-NEXT:    ret i8 [[R]]
+;
+  %x = and i8 %xx, 15
+  %cond = icmp ult i8 %y, 3
+  %sel = select i1 %cond, i8 %y, i8 %x
+  %r = add i8 %sel, 32
+  ret i8 %r
+}
+
+define i8 @select_condition_implies_highbits_op1_maybe_undef_fail(i8 %xx, i8 %y) {
+; CHECK-LABEL: @select_condition_implies_highbits_op1_maybe_undef_fail(
+; CHECK-NEXT:    [[X:%.*]] = and i8 [[XX:%.*]], 15
+; CHECK-NEXT:    [[COND:%.*]] = icmp ult i8 [[Y:%.*]], 3
+; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[COND]], i8 [[Y]], i8 [[X]]
+; CHECK-NEXT:    [[R:%.*]] = add i8 [[SEL]], 32
+; CHECK-NEXT:    ret i8 [[R]]
+;
+  %x = and i8 %xx, 15
+  %cond = icmp ult i8 %y, 3
+  %sel = select i1 %cond, i8 %y, i8 %x
+  %r = add i8 %sel, 32
+  ret i8 %r
+}
+
+define i8 @select_condition_implies_highbits_op2(i8 %xx, i8 noundef %y) {
+; CHECK-LABEL: @select_condition_implies_highbits_op2(
+; CHECK-NEXT:    [[X:%.*]] = and i8 [[XX:%.*]], 15
+; CHECK-NEXT:    [[COND:%.*]] = icmp ugt i8 [[Y:%.*]], 3
+; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[COND]], i8 [[X]], i8 [[Y]]
+; CHECK-NEXT:    [[R:%.*]] = add i8 [[SEL]], 32
+; CHECK-NEXT:    ret i8 [[R]]
+;
+  %x = and i8 %xx, 15
+  %cond = icmp ugt i8 %y, 3
+  %sel = select i1 %cond, i8 %x, i8 %y
+  %r = add i8 %sel, 32
+  ret i8 %r
+}
+
+define i8 @select_condition_implies_highbits_op1_and(i8 %xx, i8 noundef %y, i1 %other_cond) {
+; CHECK-LABEL: @select_condition_implies_highbits_op1_and(
+; CHECK-NEXT:    [[X:%.*]] = and i8 [[XX:%.*]], 15
+; CHECK-NEXT:    [[COND0:%.*]] = icmp ult i8 [[Y:%.*]], 3
+; CHECK-NEXT:    [[COND:%.*]] = and i1 [[COND0]], [[OTHER_COND:%.*]]
+; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[COND]], i8 [[Y]], i8 [[X]]
+; CHECK-NEXT:    [[R:%.*]] = add i8 [[SEL]], 32
+; CHECK-NEXT:    ret i8 [[R]]
+;
+  %x = and i8 %xx, 15
+  %cond0 = icmp ult i8 %y, 3
+  %cond = and i1 %cond0, %other_cond
+  %sel = select i1 %cond, i8 %y, i8 %x
+  %r = add i8 %sel, 32
+  ret i8 %r
+}
+
+define i8 @select_condition_implies_highbits_op2_or(i8 %xx, i8 noundef %y, i1 %other_cond) {
+; CHECK-LABEL: @select_condition_implies_highbits_op2_or(
+; CHECK-NEXT:    [[X:%.*]] = and i8 [[XX:%.*]], 15
+; CHECK-NEXT:    [[COND0:%.*]] = icmp ugt i8 [[Y:%.*]], 3
+; CHECK-NEXT:    [[COND:%.*]] = or i1 [[COND0]], [[OTHER_COND:%.*]]
+; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[COND]], i8 [[X]], i8 [[Y]]
+; CHECK-NEXT:    [[R:%.*]] = add i8 [[SEL]], 32
+; CHECK-NEXT:    ret i8 [[R]]
+;
+  %x = and i8 %xx, 15
+  %cond0 = icmp ugt i8 %y, 3
+  %cond = or i1 %cond0, %other_cond
+  %sel = select i1 %cond, i8 %x, i8 %y
+  %r = add i8 %sel, 32
+  ret i8 %r
+}