forked from OSchip/llvm-project
54 lines
1.9 KiB
LLVM
54 lines
1.9 KiB
LLVM
|
; RUN: opt < %s -loop-unroll -codegenprepare -S | FileCheck %s
|
||
|
|
|
||
|
|
; This test is a worst-case scenario for bitreversal/byteswap detection.
|
||
|
|
; After loop unrolling (the unrolled loop is unreadably large so it has been kept
|
||
|
|
; rolled here), we have a binary tree of OR operands (as bitreversal detection
|
||
|
|
; looks straight through shifts):
|
||
|
|
;
|
||
|
|
; OR
|
||
|
|
; | \
|
||
|
|
; | LSHR
|
||
|
|
; | /
|
||
|
|
; OR
|
||
|
|
; | \
|
||
|
|
; | LSHR
|
||
|
|
; | /
|
||
|
|
; OR
|
||
|
|
;
|
||
|
|
; This results in exponential runtime. The loop here is 32 iterations which will
|
||
|
|
; totally hang if we don't deal with this case cleverly.
|
||
|
|
|
||
|
|
@b = common global i32 0, align 4
|
||
|
|
|
||
|
|
; CHECK: define i32 @fn1
|
||
|
|
define i32 @fn1() #0 {
|
||
|
|
entry:
|
||
|
|
%b.promoted = load i32, i32* @b, align 4, !tbaa !2
|
||
|
|
br label %for.body
|
||
|
|
|
||
|
|
for.body: ; preds = %for.body, %entry
|
||
|
|
%or4 = phi i32 [ %b.promoted, %entry ], [ %or, %for.body ]
|
||
|
|
%i.03 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
|
||
|
|
%shr = lshr i32 %or4, 1
|
||
|
|
%or = or i32 %shr, %or4
|
||
|
|
%inc = add nuw nsw i32 %i.03, 1
|
||
|
|
%exitcond = icmp eq i32 %inc, 32
|
||
|
|
br i1 %exitcond, label %for.end, label %for.body
|
||
|
|
|
||
|
|
for.end: ; preds = %for.body
|
||
|
|
store i32 %or, i32* @b, align 4, !tbaa !2
|
||
|
|
ret i32 undef
|
||
|
|
}
|
||
|
|
|
||
|
|
attributes #0 = { norecurse nounwind ssp uwtable "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="core2" "target-features"="+cx16,+fxsr,+mmx,+sse,+sse2,+sse3,+ssse3" "unsafe-fp-math"="false" "use-soft-float"="false" }
|
||
|
|
|
||
|
|
!llvm.module.flags = !{!0}
|
||
|
|
!llvm.ident = !{!1}
|
||
|
|
|
||
|
|
!0 = !{i32 1, !"PIC Level", i32 2}
|
||
|
|
!1 = !{!"clang version 3.8.0 (http://llvm.org/git/clang.git eb70f4e9cc9a4dc3dd57b032fb858d56b4b64a0e)"}
|
||
|
|
!2 = !{!3, !3, i64 0}
|
||
|
|
!3 = !{!"int", !4, i64 0}
|
||
|
|
!4 = !{!"omnipotent char", !5, i64 0}
|
||
|
|
!5 = !{!"Simple C/C++ TBAA"}
|