[JumpThreading][NFC] Precommit tests for pr76609

Author: XChy

llvm/test/Transforms/JumpThreading/uncond-no-phi.ll

@@ -0,0 +1,123 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
+; RUN: opt -passes=jump-threading -S < %s | FileCheck %s
+
+define i1 @if_else(i1 %c, i1 %c1) {
+; CHECK-LABEL: define i1 @if_else(
+; CHECK-SAME: i1 [[C:%.*]], i1 [[C1:%.*]]) {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br i1 [[C]], label [[THEN:%.*]], label [[RETURN:%.*]]
+; CHECK:       then:
+; CHECK-NEXT:    call void @dummy()
+; CHECK-NEXT:    br i1 [[C1]], label [[RETURN]], label [[RETURN1:%.*]]
+; CHECK:       else:
+; CHECK-NEXT:    br label [[RETURN1]]
+; CHECK:       return:
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = phi i1 [ true, [[RETURN]] ], [ false, [[THEN]] ]
+; CHECK-NEXT:    ret i1 [[RETVAL_0]]
+;
+entry:
+  br i1 %c, label %then, label %else
+
+then:
+  call void @dummy()
+  br i1 %c1, label %else, label %return
+
+else:
+  br label %return
+
+return:
+  %retval.0 = phi i1 [ true, %else ], [ false, %then ]
+  ret i1 %retval.0
+}
+
+define i8 @switch_uncond(i8 %arg) {
+; CHECK-LABEL: define i8 @switch_uncond(
+; CHECK-SAME: i8 [[ARG:%.*]]) {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    switch i8 [[ARG]], label [[DEFAULT:%.*]] [
+; CHECK-NEXT:      i8 0, label [[BB1:%.*]]
+; CHECK-NEXT:      i8 1, label [[BB3:%.*]]
+; CHECK-NEXT:      i8 2, label [[BB2:%.*]]
+; CHECK-NEXT:      i8 3, label [[END:%.*]]
+; CHECK-NEXT:    ]
+; CHECK:       default:
+; CHECK-NEXT:    unreachable
+; CHECK:       bb:
+; CHECK-NEXT:    call void @dummy()
+; CHECK-NEXT:    br label [[BB2]]
+; CHECK:       bb1:
+; CHECK-NEXT:    call void @dummy()
+; CHECK-NEXT:    br label [[BB2]]
+; CHECK:       bb2:
+; CHECK-NEXT:    br label [[END]]
+; CHECK:       end:
+; CHECK-NEXT:    [[PHI:%.*]] = phi i8 [ 0, [[BB2]] ], [ 1, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    ret i8 [[PHI]]
+;
+entry:
+  switch i8 %arg, label %default [
+  i8 0, label %bb
+  i8 1, label %bb1
+  i8 2, label %bb2
+  i8 3, label %end
+  ]
+
+default:
+  unreachable
+
+bb:
+  call void @dummy()
+  br label %bb2
+
+bb1:
+  call void @dummy()
+  br label %bb2
+
+; Predecessors of %bb2 are %bb and %bb1, they are not identical.
+; So we can thread %bb2.
+bb2:
+  br label %end
+
+end:
+  %phi = phi i8 [ 0, %bb2 ], [ 1, %entry ]
+  ret i8 %phi
+}
+
+define i8 @switch_uncond_fail(i8 %arg) {
+; CHECK-LABEL: define i8 @switch_uncond_fail(
+; CHECK-SAME: i8 [[ARG:%.*]]) {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    switch i8 [[ARG]], label [[DEFAULT:%.*]] [
+; CHECK-NEXT:      i8 0, label [[BB:%.*]]
+; CHECK-NEXT:      i8 1, label [[BB]]
+; CHECK-NEXT:      i8 2, label [[END:%.*]]
+; CHECK-NEXT:    ]
+; CHECK:       default:
+; CHECK-NEXT:    br label [[END]]
+; CHECK:       bb:
+; CHECK-NEXT:    br label [[END]]
+; CHECK:       end:
+; CHECK-NEXT:    [[PHI:%.*]] = phi i8 [ 0, [[BB]] ], [ 1, [[ENTRY:%.*]] ], [ 2, [[DEFAULT]] ]
+; CHECK-NEXT:    ret i8 [[PHI]]
+;
+entry:
+  switch i8 %arg, label %default [
+  i8 0, label %bb
+  i8 1, label %bb
+  i8 2, label %end
+  ]
+
+default:
+  br label %end
+
+; Predecessor of %bb is only %entry (though there are two in predecessor list),
+; thus it's unthreadable.
+bb:
+  br label %end
+
+end:
+  %phi = phi i8 [ 0, %bb ], [ 1, %entry ], [ 2, %default ]
+  ret i8 %phi
+}
+
+declare void @dummy()