forked from OSchip/llvm-project
49 lines
2.0 KiB
LLVM
49 lines
2.0 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
|
|
; RUN: opt < %s -dse -S | FileCheck %s
|
|
|
|
@BUFFER = external dso_local local_unnamed_addr global [0 x i8], align 1
|
|
|
|
define void @MissedDSEOpportunity(i64 %idx, i1* 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], [0 x i8]* @BUFFER, i64 0, i64 [[IDX:%.*]]
|
|
; CHECK-NEXT: [[BC:%.*]] = bitcast i8* [[GEP]] to i64*
|
|
; CHECK-NEXT: [[CC0:%.*]] = load volatile i1, i1* [[CC:%.*]], align 1
|
|
; CHECK-NEXT: br i1 [[CC0]], label [[HEAD:%.*]], label [[EXIT:%.*]]
|
|
; CHECK: head:
|
|
; CHECK-NEXT: [[CC1:%.*]] = load volatile i1, i1* [[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, i64* [[BC]], 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], [0 x i8]* @BUFFER, i64 0, i64 %idx
|
|
%bc = bitcast i8* %gep to i64*
|
|
%cc0 = load volatile i1, i1* %cc, align 1
|
|
br i1 %cc0, label %head, label %exit
|
|
|
|
head: ; preds = %entry, %head
|
|
%cc1 = load volatile i1, i1* %cc, align 1
|
|
br i1 %cc1, label %head, label %exit.loopexit
|
|
|
|
exit.loopexit: ; preds = %head
|
|
; Dead store
|
|
store i64 2, i64* %bc, align 4
|
|
br label %exit
|
|
|
|
exit: ; preds = %exit.loopexit, %entry
|
|
; Killer store
|
|
store i64 0, i64* %bc, align 4
|
|
ret void
|
|
} |