1; RUN: opt < %s -gvn -enable-load-pre -S | FileCheck %s 2; RUN: opt < %s -passes="gvn<load-pre>" -enable-load-pre=false -S | FileCheck %s 3; This testcase assumed we'll PRE the load into %for.cond, but we don't actually 4; verify that doing so is safe. If there didn't _happen_ to be a load in 5; %for.end, we would actually be lengthening the execution on some paths, and 6; we were never actually checking that case. Now we actually do perform some 7; conservative checking to make sure we don't make paths longer, but we don't 8; currently get this case, which we got lucky on previously. 9; 10; Now that that faulty assumption is corrected, test that we DON'T incorrectly 11; hoist the load. Doing the right thing for the wrong reasons is still a bug. 12 13@p = external global i32 14define i32 @f(i32 %n) nounwind { 15entry: 16 br label %for.cond 17 18for.cond: ; preds = %for.inc, %entry 19 %i.0 = phi i32 [ 0, %entry ], [ %indvar.next, %for.inc ] ; <i32> [#uses=2] 20 %cmp = icmp slt i32 %i.0, %n ; <i1> [#uses=1] 21 br i1 %cmp, label %for.body, label %for.cond.for.end_crit_edge 22 23for.cond.for.end_crit_edge: ; preds = %for.cond 24 br label %for.end 25 26; CHECK: for.body: 27; CHECK-NEXT: %tmp3 = load i32, i32* @p 28for.body: ; preds = %for.cond 29 %tmp3 = load i32, i32* @p ; <i32> [#uses=1] 30 %dec = add i32 %tmp3, -1 ; <i32> [#uses=2] 31 store i32 %dec, i32* @p 32 %cmp6 = icmp slt i32 %dec, 0 ; <i1> [#uses=1] 33 br i1 %cmp6, label %for.body.for.end_crit_edge, label %for.inc 34 35; CHECK: for.body.for.end_crit_edge: 36for.body.for.end_crit_edge: ; preds = %for.body 37 br label %for.end 38 39for.inc: ; preds = %for.body 40 %indvar.next = add i32 %i.0, 1 ; <i32> [#uses=1] 41 br label %for.cond 42 43for.end: ; preds = %for.body.for.end_crit_edge, %for.cond.for.end_crit_edge 44 %tmp9 = load i32, i32* @p ; <i32> [#uses=1] 45 ret i32 %tmp9 46} 47