[LVI][CVP] Pre-commmit for undef with abs

Author: dianqk

llvm/test/Transforms/CorrelatedValuePropagation/abs.ll

@@ -2,6 +2,7 @@
 ; RUN: opt < %s -passes=correlated-propagation -S | FileCheck %s
 
 declare void @llvm.assume(i1)
+declare i32 @llvm.abs.i32(i32, i1)
 declare i8 @llvm.abs.i8(i8, i1)
 declare i1 @llvm.abs.i1(i1, i1)
 
@@ -387,3 +388,131 @@ define i1 @pr59887(i1 %x, i1 %c) {
   %res = select i1 %c, i1 %abs, i1 false
   ret i1 %res
 }
+
+; Because of `undef`, We can't delete `abs`.
+; We can't replace the `abs` argument with true either.
+define i32 @pr68381_undef_abs_false(i1 %c0, i1 %c1, i8 %v1) {
+; CHECK-LABEL: @pr68381_undef_abs_false(
+; CHECK-NEXT:  start:
+; CHECK-NEXT:    br i1 [[C0:%.*]], label [[BB0:%.*]], label [[BB1:%.*]]
+; CHECK:       bb0:
+; CHECK-NEXT:    [[V1_I32:%.*]] = zext i8 [[V1:%.*]] to i32
+; CHECK-NEXT:    br label [[BB1]]
+; CHECK:       bb1:
+; CHECK-NEXT:    [[X:%.*]] = phi i32 [ [[V1_I32]], [[BB0]] ], [ undef, [[START:%.*]] ]
+; CHECK-NEXT:    br i1 [[C1:%.*]], label [[BB0]], label [[BB2:%.*]]
+; CHECK:       bb2:
+; CHECK-NEXT:    ret i32 [[X]]
+;
+start:
+  br i1 %c0, label %bb0, label %bb1
+
+bb0:
+  %v1_i32 = zext i8 %v1 to i32
+  br label %bb1
+
+bb1:
+  %x = phi i32 [ %v1_i32, %bb0 ], [ undef, %start ]
+  br i1 %c1, label %bb0, label %bb2
+
+bb2:
+  %z = call i32 @llvm.abs.i32(i32 %x, i1 false)
+  ret i32 %z
+}
+
+; Because of `and`, we can delete `abs`.
+define i32 @pr68381_undef_abs_false_and(i1 %c0, i1 %c1, i8 %v1) {
+; CHECK-LABEL: @pr68381_undef_abs_false_and(
+; CHECK-NEXT:  start:
+; CHECK-NEXT:    br i1 [[C0:%.*]], label [[BB0:%.*]], label [[BB1:%.*]]
+; CHECK:       bb0:
+; CHECK-NEXT:    [[V1_I32:%.*]] = zext i8 [[V1:%.*]] to i32
+; CHECK-NEXT:    br label [[BB1]]
+; CHECK:       bb1:
+; CHECK-NEXT:    [[X:%.*]] = phi i32 [ [[V1_I32]], [[BB0]] ], [ undef, [[START:%.*]] ]
+; CHECK-NEXT:    br i1 [[C1:%.*]], label [[BB0]], label [[BB2:%.*]]
+; CHECK:       bb2:
+; CHECK-NEXT:    [[Y:%.*]] = and i32 [[X]], 255
+; CHECK-NEXT:    ret i32 [[Y]]
+;
+start:
+  br i1 %c0, label %bb0, label %bb1
+
+bb0:
+  %v1_i32 = zext i8 %v1 to i32
+  br label %bb1
+
+bb1:
+  %x = phi i32 [ %v1_i32, %bb0 ], [ undef, %start ]
+  br i1 %c1, label %bb0, label %bb2
+
+bb2:
+  %y = and i32 %x, 255
+  %z = call i32 @llvm.abs.i32(i32 %y, i1 false)
+  ret i32 %z
+}
+
+; Because of `undef`, we can't replace `abs` with `sub`.
+define i32 @pr68381_undef_abs_false_sub(i1 %c0, i1 %c1, i32 %v1, i32 %v2) {
+; CHECK-LABEL: @pr68381_undef_abs_false_sub(
+; CHECK-NEXT:  start:
+; CHECK-NEXT:    br i1 [[C0:%.*]], label [[BB0:%.*]], label [[BB1:%.*]]
+; CHECK:       bb0:
+; CHECK-NEXT:    [[V3:%.*]] = add i32 [[V1:%.*]], [[V2:%.*]]
+; CHECK-NEXT:    [[LIM:%.*]] = icmp sle i32 [[V3]], -1
+; CHECK-NEXT:    call void @llvm.assume(i1 [[LIM]])
+; CHECK-NEXT:    br label [[BB1]]
+; CHECK:       bb1:
+; CHECK-NEXT:    [[X:%.*]] = phi i32 [ [[V3]], [[BB0]] ], [ undef, [[START:%.*]] ]
+; CHECK-NEXT:    br i1 [[C1:%.*]], label [[BB0]], label [[BB2:%.*]]
+; CHECK:       bb2:
+; CHECK-NEXT:    [[Z1:%.*]] = sub i32 0, [[X]]
+; CHECK-NEXT:    ret i32 [[Z1]]
+;
+start:
+  br i1 %c0, label %bb0, label %bb1
+
+bb0:
+  %v3 = add i32 %v1, %v2
+  %lim = icmp sle i32 %v3, -1
+  call void @llvm.assume(i1 %lim)
+  br label %bb1
+
+bb1:
+  %x = phi i32 [ %v3, %bb0 ], [ undef, %start ]
+  br i1 %c1, label %bb0, label %bb2
+
+bb2:
+  %z = call i32 @llvm.abs.i32(i32 %x, i1 false)
+  ret i32 %z
+}
+
+; We can delete `abs`.
+define i32 @pr68381_undef_abs_true(i1 %c0, i1 %c1, i8 %v1) {
+; CHECK-LABEL: @pr68381_undef_abs_true(
+; CHECK-NEXT:  start:
+; CHECK-NEXT:    br i1 [[C0:%.*]], label [[BB0:%.*]], label [[BB1:%.*]]
+; CHECK:       bb0:
+; CHECK-NEXT:    [[V1_I32:%.*]] = zext i8 [[V1:%.*]] to i32
+; CHECK-NEXT:    br label [[BB1]]
+; CHECK:       bb1:
+; CHECK-NEXT:    [[X:%.*]] = phi i32 [ [[V1_I32]], [[BB0]] ], [ undef, [[START:%.*]] ]
+; CHECK-NEXT:    br i1 [[C1:%.*]], label [[BB0]], label [[BB2:%.*]]
+; CHECK:       bb2:
+; CHECK-NEXT:    ret i32 [[X]]
+;
+start:
+  br i1 %c0, label %bb0, label %bb1
+
+bb0:
+  %v1_i32 = zext i8 %v1 to i32
+  br label %bb1
+
+bb1:
+  %x = phi i32 [ %v1_i32, %bb0 ], [ undef, %start ]
+  br i1 %c1, label %bb0, label %bb2
+
+bb2:
+  %z = call i32 @llvm.abs.i32(i32 %x, i1 true)
+  ret i32 %z
+}