multiple-exits.ll
3.99 KB
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; Checks whether dead loops with multiple exits can be eliminated.
; Note that we loop simplify and LCSSA over the test cases to make sure the
; critical components remain after those passes and are visible to the loop
; deletion pass.
;
; RUN: opt < %s -loop-simplify -lcssa -S | FileCheck %s --check-prefixes=CHECK,BEFORE
; RUN: opt < %s -loop-deletion -S | FileCheck %s --check-prefixes=CHECK,AFTER
;
; RUN: opt < %s -passes=no-op-loop -S | FileCheck %s --check-prefixes=CHECK,BEFORE
; RUN: opt < %s -passes=loop-deletion -S | FileCheck %s --check-prefixes=CHECK,AFTER
define void @foo(i64 %n, i64 %m) nounwind {
; CHECK-LABEL: @foo(
entry:
br label %bb
; CHECK: entry:
; BEFORE-NEXT: br label %bb
; AFTER-NEXT: br label %return
bb:
%x.0 = phi i64 [ 0, %entry ], [ %t0, %bb2 ]
%t0 = add i64 %x.0, 1
%t1 = icmp slt i64 %x.0, %n
br i1 %t1, label %bb2, label %return
; BEFORE: bb:
; BEFORE: br i1 {{.*}}, label %bb2, label %return
; AFTER-NOT: bb:
; AFTER-NOT: br
bb2:
%t2 = icmp slt i64 %x.0, %m
br i1 %t1, label %bb, label %return
; BEFORE: bb2:
; BEFORE: br i1 {{.*}}, label %bb, label %return
; AFTER-NOT: bb2:
; AFTER-NOT: br
return:
ret void
; CHECK: return:
; CHECK-NEXT: ret void
}
define i64 @bar(i64 %n, i64 %m, i64 %maybe_zero) nounwind {
; CHECK-LABEL: @bar(
entry:
br label %bb
; CHECK: entry:
; BEFORE-NEXT: br label %bb
; AFTER-NEXT: br label %return
bb:
%x.0 = phi i64 [ 0, %entry ], [ %t0, %bb3 ]
%t0 = add i64 %x.0, 1
%t1 = icmp slt i64 %x.0, %n
br i1 %t1, label %bb2, label %return
; BEFORE: bb:
; BEFORE: br i1 {{.*}}, label %bb2, label %return
; AFTER-NOT: bb:
; AFTER-NOT: br
bb2:
%t2 = icmp slt i64 %x.0, %m
; This unused division prevents unifying this loop exit path with others
; because it can be deleted but cannot be hoisted.
%unused1 = udiv i64 42, %maybe_zero
br i1 %t2, label %bb3, label %return
; BEFORE: bb2:
; BEFORE: br i1 {{.*}}, label %bb3, label %return
; AFTER-NOT: bb2:
; AFTER-NOT: br
bb3:
%t3 = icmp slt i64 %x.0, %m
; This unused division prevents unifying this loop exit path with others
; because it can be deleted but cannot be hoisted.
%unused2 = sdiv i64 42, %maybe_zero
br i1 %t3, label %bb, label %return
; BEFORE: bb3:
; BEFORE: br i1 {{.*}}, label %bb, label %return
; AFTER-NOT: bb3:
; AFTER-NOT: br
return:
%x.lcssa = phi i64 [ 10, %bb ], [ 10, %bb2 ], [ 10, %bb3 ]
ret i64 %x.lcssa
; CHECK: return:
; BEFORE-NEXT: %[[X:.*]] = phi i64 [ 10, %bb ], [ 10, %bb2 ], [ 10, %bb3 ]
; AFTER-NEXT: %[[X:.*]] = phi i64 [ 10, %entry ]
; CHECK-NEXT: ret i64 %[[X]]
}
; This function has a loop which looks like @bar's but that cannot be deleted
; because which path we exit through determines which value is selected.
define i64 @baz(i64 %n, i64 %m, i64 %maybe_zero) nounwind {
; CHECK-LABEL: @baz(
entry:
br label %bb
; CHECK: entry:
; CHECK-NEXT: br label %bb
bb:
%x.0 = phi i64 [ 0, %entry ], [ %t0, %bb3 ]
%t0 = add i64 %x.0, 1
%t1 = icmp slt i64 %x.0, %n
br i1 %t1, label %bb2, label %return
; CHECK: bb:
; CHECK: br i1 {{.*}}, label %bb2, label %return
bb2:
%t2 = icmp slt i64 %x.0, %m
; This unused division prevents unifying this loop exit path with others
; because it can be deleted but cannot be hoisted.
%unused1 = udiv i64 42, %maybe_zero
br i1 %t2, label %bb3, label %return
; CHECK: bb2:
; CHECK: br i1 {{.*}}, label %bb3, label %return
bb3:
%t3 = icmp slt i64 %x.0, %m
; This unused division prevents unifying this loop exit path with others
; because it can be deleted but cannot be hoisted.
%unused2 = sdiv i64 42, %maybe_zero
br i1 %t3, label %bb, label %return
; CHECK: bb3:
; CHECK: br i1 {{.*}}, label %bb, label %return
return:
%x.lcssa = phi i64 [ 12, %bb ], [ 10, %bb2 ], [ 10, %bb3 ]
ret i64 %x.lcssa
; CHECK: return:
; CHECK-NEXT: %[[X:.*]] = phi i64 [ 12, %bb ], [ 10, %bb2 ], [ 10, %bb3 ]
; CHECK-NEXT: ret i64 %[[X]]
}