1 ; RUN: opt < %s -gvn -enable-load-pre -S | FileCheck %s 2 ; This testcase assumed we'll PRE the load into %for.cond, but we don't actually 3 ; verify that doing so is safe. If there didn't _happen_ to be a load in 4 ; %for.end, we would actually be lengthening the execution on some paths, and 5 ; we were never actually checking that case. Now we actually do perform some 6 ; conservative checking to make sure we don't make paths longer, but we don't 7 ; currently get this case, which we got lucky on previously. 8 ; 9 ; Now that that faulty assumption is corrected, test that we DON'T incorrectly 10 ; hoist the load. Doing the right thing for the wrong reasons is still a bug. 11 12 @p = external global i32 13 define i32 @f(i32 %n) nounwind { 14 entry: 15 br label %for.cond 16 17 for.cond: ; preds = %for.inc, %entry 18 %i.0 = phi i32 [ 0, %entry ], [ %indvar.next, %for.inc ] ; <i32> [#uses=2] 19 %cmp = icmp slt i32 %i.0, %n ; <i1> [#uses=1] 20 br i1 %cmp, label %for.body, label %for.cond.for.end_crit_edge 21 22 for.cond.for.end_crit_edge: ; preds = %for.cond 23 br label %for.end 24 25 ; CHECK: for.body: 26 ; CHECK-NEXT: %tmp3 = load i32* @p 27 for.body: ; preds = %for.cond 28 %tmp3 = load i32* @p ; <i32> [#uses=1] 29 %dec = add i32 %tmp3, -1 ; <i32> [#uses=2] 30 store i32 %dec, i32* @p 31 %cmp6 = icmp slt i32 %dec, 0 ; <i1> [#uses=1] 32 br i1 %cmp6, label %for.body.for.end_crit_edge, label %for.inc 33 34 ; CHECK: for.body.for.end_crit_edge: 35 for.body.for.end_crit_edge: ; preds = %for.body 36 br label %for.end 37 38 for.inc: ; preds = %for.body 39 %indvar.next = add i32 %i.0, 1 ; <i32> [#uses=1] 40 br label %for.cond 41 42 for.end: ; preds = %for.body.for.end_crit_edge, %for.cond.for.end_crit_edge 43 %tmp9 = load i32* @p ; <i32> [#uses=1] 44 ret i32 %tmp9 45 } 46
