1; NOTE: Assertions have been autogenerated by utils/update_test_checks.py 2; RUN: opt < %s -dse -S | FileCheck %s 3 4@BUFFER = external dso_local local_unnamed_addr global [0 x i8], align 1 5 6define void @MissedDSEOpportunity(i64 %idx, i1* noalias %cc) { 7; 8; The DSE pass will try to kill the store in the loop exit block using the 9; store in the function exit block. The loop invariant check on the pointer 10; used by the stores should trivially return true because a pointer defined 11; in the entry block of a function is loop invariant by definition. In fact 12; the entry block of a function cannot have predecessors or be part of a loop. 13; 14; CHECK-LABEL: @MissedDSEOpportunity( 15; CHECK-NEXT: entry: 16; CHECK-NEXT: [[GEP:%.*]] = getelementptr inbounds [0 x i8], [0 x i8]* @BUFFER, i64 0, i64 [[IDX:%.*]] 17; CHECK-NEXT: [[BC:%.*]] = bitcast i8* [[GEP]] to i64* 18; CHECK-NEXT: [[CC0:%.*]] = load volatile i1, i1* [[CC:%.*]], align 1 19; CHECK-NEXT: br i1 [[CC0]], label [[HEAD:%.*]], label [[EXIT:%.*]] 20; CHECK: head: 21; CHECK-NEXT: [[CC1:%.*]] = load volatile i1, i1* [[CC]], align 1 22; CHECK-NEXT: br i1 [[CC1]], label [[HEAD]], label [[EXIT_LOOPEXIT:%.*]] 23; CHECK: exit.loopexit: 24; CHECK-NEXT: br label [[EXIT]] 25; CHECK: exit: 26; CHECK-NEXT: store i64 0, i64* [[BC]], align 4 27; CHECK-NEXT: ret void 28; 29entry: 30 ; The entry block cannot have predecessors or be part of a loop 31 %gep = getelementptr inbounds [0 x i8], [0 x i8]* @BUFFER, i64 0, i64 %idx 32 %bc = bitcast i8* %gep to i64* 33 %cc0 = load volatile i1, i1* %cc, align 1 34 br i1 %cc0, label %head, label %exit 35 36head: ; preds = %entry, %head 37 %cc1 = load volatile i1, i1* %cc, align 1 38 br i1 %cc1, label %head, label %exit.loopexit 39 40exit.loopexit: ; preds = %head 41 ; Dead store 42 store i64 2, i64* %bc, align 4 43 br label %exit 44 45exit: ; preds = %exit.loopexit, %entry 46 ; Killer store 47 store i64 0, i64* %bc, align 4 48 ret void 49}