llvm/test/Transforms/IndVarSimplify/lftr-udiv-tripcount.ll
Sanjoy Das 17e08f50b9 [SCEV] Strengthen SCEVExpander::isHighCostExpansion.
Summary:

Teach `isHighCostExpansion` to consider divisions by power-of-two
constants as cheap and add a test case.  This change is needed for a new
user of `isHighCostExpansion` that will be added in a subsequent change.

Depends on D8995.

Reviewers: atrick

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D8993

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234845 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-14 03:20:32 +00:00

30 lines
866 B
LLVM

; RUN: opt < %s -indvars -S | FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
; It is okay to do LFTR on this loop even though the trip count is a
; division because in this case the division can be optimized to a
; shift.
define void @foo(i8* %a, i8 %n) nounwind uwtable ssp {
; CHECK-LABEL: @foo(
entry:
%e = icmp sgt i8 %n, 3
br i1 %e, label %loop, label %exit
loop:
; CHECK-LABEL: loop:
%i = phi i8 [ 0, %entry ], [ %i.inc, %loop ]
%i1 = phi i8 [ 0, %entry ], [ %i1.inc, %loop ]
%i.inc = add nsw i8 %i, 4
%i1.inc = add i8 %i1, 1
store volatile i8 0, i8* %a
%c = icmp slt i8 %i, %n
; CHECK-LABEL: %exitcond = icmp ne i8 %i1.inc
br i1 %c, label %loop, label %exit
exit:
; CHECK-LABEL: exit:
ret void
}