| 123456789101112131415161718192021222324252627282930313233343536373839404142434445 |
- ; RUN: opt < %s -gvn -enable-load-pre -S | FileCheck %s
- ; This testcase assumed we'll PRE the load into %for.cond, but we don't actually
- ; verify that doing so is safe. If there didn't _happen_ to be a load in
- ; %for.end, we would actually be lengthening the execution on some paths, and
- ; we were never actually checking that case. Now we actually do perform some
- ; conservative checking to make sure we don't make paths longer, but we don't
- ; currently get this case, which we got lucky on previously.
- ;
- ; Now that that faulty assumption is corrected, test that we DON'T incorrectly
- ; hoist the load. Doing the right thing for the wrong reasons is still a bug.
- @p = external global i32
- define i32 @f(i32 %n) nounwind {
- entry:
- br label %for.cond
- for.cond: ; preds = %for.inc, %entry
- %i.0 = phi i32 [ 0, %entry ], [ %indvar.next, %for.inc ] ; <i32> [#uses=2]
- %cmp = icmp slt i32 %i.0, %n ; <i1> [#uses=1]
- br i1 %cmp, label %for.body, label %for.cond.for.end_crit_edge
- for.cond.for.end_crit_edge: ; preds = %for.cond
- br label %for.end
- ; CHECK: for.body:
- ; CHECK-NEXT: %tmp3 = load i32, i32* @p
- for.body: ; preds = %for.cond
- %tmp3 = load i32, i32* @p ; <i32> [#uses=1]
- %dec = add i32 %tmp3, -1 ; <i32> [#uses=2]
- store i32 %dec, i32* @p
- %cmp6 = icmp slt i32 %dec, 0 ; <i1> [#uses=1]
- br i1 %cmp6, label %for.body.for.end_crit_edge, label %for.inc
- ; CHECK: for.body.for.end_crit_edge:
- for.body.for.end_crit_edge: ; preds = %for.body
- br label %for.end
- for.inc: ; preds = %for.body
- %indvar.next = add i32 %i.0, 1 ; <i32> [#uses=1]
- br label %for.cond
- for.end: ; preds = %for.body.for.end_crit_edge, %for.cond.for.end_crit_edge
- %tmp9 = load i32, i32* @p ; <i32> [#uses=1]
- ret i32 %tmp9
- }
|
