47 lines · plain
1; NOTE: Assertions have been autogenerated by utils/update_test_checks.py2; RUN: opt < %s -passes=dse -S | FileCheck %s3 4@BUFFER = external dso_local local_unnamed_addr global [0 x i8], align 15 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 the9; store in the function exit block. The loop invariant check on the pointer10; used by the stores should trivially return true because a pointer defined11; in the entry block of a function is loop invariant by definition. In fact12; 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 118; CHECK-NEXT: br i1 [[CC0]], label [[HEAD:%.*]], label [[EXIT:%.*]]19; CHECK: head:20; CHECK-NEXT: [[CC1:%.*]] = load volatile i1, ptr [[CC]], align 121; 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 426; CHECK-NEXT: ret void27;28entry:29 ; The entry block cannot have predecessors or be part of a loop30 %gep = getelementptr inbounds [0 x i8], ptr @BUFFER, i64 0, i64 %idx31 %cc0 = load volatile i1, ptr %cc, align 132 br i1 %cc0, label %head, label %exit33 34head: ; preds = %entry, %head35 %cc1 = load volatile i1, ptr %cc, align 136 br i1 %cc1, label %head, label %exit.loopexit37 38exit.loopexit: ; preds = %head39 ; Dead store40 store i64 2, ptr %gep, align 441 br label %exit42 43exit: ; preds = %exit.loopexit, %entry44 ; Killer store45 store i64 0, ptr %gep, align 446 ret void47}