1; NOTE: Assertions have been autogenerated by utils/update_test_checks.py 2; RUN: opt < %s -passes=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, ptr 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], ptr @BUFFER, i64 0, i64 [[IDX:%.*]] 17; CHECK-NEXT: [[CC0:%.*]] = load volatile i1, ptr [[CC:%.*]], align 1 18; CHECK-NEXT: br i1 [[CC0]], label [[HEAD:%.*]], label [[EXIT:%.*]] 19; CHECK: head: 20; CHECK-NEXT: [[CC1:%.*]] = load volatile i1, ptr [[CC]], align 1 21; CHECK-NEXT: br i1 [[CC1]], label [[HEAD]], label [[EXIT_LOOPEXIT:%.*]] 22; CHECK: exit.loopexit: 23; CHECK-NEXT: br label [[EXIT]] 24; CHECK: exit: 25; CHECK-NEXT: store i64 0, ptr [[GEP]], align 4 26; CHECK-NEXT: ret void 27; 28entry: 29 ; The entry block cannot have predecessors or be part of a loop 30 %gep = getelementptr inbounds [0 x i8], ptr @BUFFER, i64 0, i64 %idx 31 %cc0 = load volatile i1, ptr %cc, align 1 32 br i1 %cc0, label %head, label %exit 33 34head: ; preds = %entry, %head 35 %cc1 = load volatile i1, ptr %cc, align 1 36 br i1 %cc1, label %head, label %exit.loopexit 37 38exit.loopexit: ; preds = %head 39 ; Dead store 40 store i64 2, ptr %gep, align 4 41 br label %exit 42 43exit: ; preds = %exit.loopexit, %entry 44 ; Killer store 45 store i64 0, ptr %gep, align 4 46 ret void 47}