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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -passes=dse -S | FileCheck %s
@BUFFER = external dso_local local_unnamed_addr global [0 x i8], align 1
define void @MissedDSEOpportunity(i64 %idx, ptr noalias %cc) {
;
; The DSE pass will try to kill the store in the loop exit block using the
; store in the function exit block. The loop invariant check on the pointer
; used by the stores should trivially return true because a pointer defined
; in the entry block of a function is loop invariant by definition. In fact
; the entry block of a function cannot have predecessors or be part of a loop.
;
; CHECK-LABEL: @MissedDSEOpportunity(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[GEP:%.*]] = getelementptr inbounds [0 x i8], ptr @BUFFER, i64 0, i64 [[IDX:%.*]]
; CHECK-NEXT: [[CC0:%.*]] = load volatile i1, ptr [[CC:%.*]], align 1
; CHECK-NEXT: br i1 [[CC0]], label [[HEAD:%.*]], label [[EXIT:%.*]]
; CHECK: head:
; CHECK-NEXT: [[CC1:%.*]] = load volatile i1, ptr [[CC]], align 1
; CHECK-NEXT: br i1 [[CC1]], label [[HEAD]], label [[EXIT_LOOPEXIT:%.*]]
; CHECK: exit.loopexit:
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
; CHECK-NEXT: store i64 0, ptr [[GEP]], align 4
; CHECK-NEXT: ret void
;
entry:
; The entry block cannot have predecessors or be part of a loop
%gep = getelementptr inbounds [0 x i8], ptr @BUFFER, i64 0, i64 %idx
%cc0 = load volatile i1, ptr %cc, align 1
br i1 %cc0, label %head, label %exit
head: ; preds = %entry, %head
%cc1 = load volatile i1, ptr %cc, align 1
br i1 %cc1, label %head, label %exit.loopexit
exit.loopexit: ; preds = %head
; Dead store
store i64 2, ptr %gep, align 4
br label %exit
exit: ; preds = %exit.loopexit, %entry
; Killer store
store i64 0, ptr %gep, align 4
ret void
}
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