llvm.org GIT mirror llvm / release_39 test / Analysis / ScalarEvolution / nw-sub-is-not-nw-add.ll
release_39

Tree @release_39 (Download .tar.gz)

nw-sub-is-not-nw-add.ll @release_39raw · history · blame

; RUN: opt -S -indvars < %s | FileCheck %s

; Check that SCEV does not assume sub nuw X Y == add nuw X, -Y
define void @f(i32* %loc) {
; CHECK-LABEL: @f
 entry:
  br label %loop

 loop:
  %idx = phi i32 [ 6, %entry ], [ %idx.dec, %loop ]
  store i32 %idx, i32* %loc
  %idx.dec = sub nuw i32 %idx, 1
  %cond = icmp uge i32 %idx.dec, 5
  br i1 %cond, label %loop, label %exit
; CHECK-NOT: br i1 true, label %loop, label %exit

 exit:
  ret void
}

declare void @use_i1(i1)

; Check that SCEV does not assume sub nsw X Y == add nsw X, -Y
define void @g(i32 %lim) {
; CHECK-LABEL: @g
 entry:
  br label %loop

 loop:
  %idx = phi i32 [ -1, %entry ], [ %idx.dec, %loop ]
  %t = icmp sgt i32 %idx, 0
; CHECK-NOT:   call void @use_i1(i1 false)
; CHECK: call void @use_i1(i1 %t)
  call void @use_i1(i1 %t)
  %idx.dec = sub nsw i32 %idx, -2147483648
  %cond = icmp eq i32 %idx.dec, %lim
  br i1 %cond, label %loop, label %exit

 exit:
  ret void
}