llvm/test/Transforms/IndVarSimplify/loop-invariant-conditions.ll

; RUN: opt -S -indvars %s | FileCheck %s
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

define void @test1(i64 %start) {
; CHECK-LABEL: @test1
entry:
  br label %loop

loop:
  %indvars.iv = phi i64 [ %start, %entry ], [ %indvars.iv.next, %loop ]
  %indvars.iv.next = add nsw i64 %indvars.iv, 1
; CHECK: %cmp1 = icmp slt i64 %start, -1
  %cmp1 = icmp slt i64 %indvars.iv, -1
  br i1 %cmp1, label %for.end, label %loop

for.end:                                          ; preds = %if.end, %entry
  ret void
}

define void @test2(i64 %start) {
; CHECK-LABEL: @test2
entry:
  br label %loop

loop:
  %indvars.iv = phi i64 [ %start, %entry ], [ %indvars.iv.next, %loop ]
  %indvars.iv.next = add nsw i64 %indvars.iv, 1
; CHECK: %cmp1 = icmp sle i64 %start, -1
  %cmp1 = icmp sle i64 %indvars.iv, -1
  br i1 %cmp1, label %for.end, label %loop

for.end:                                          ; preds = %if.end, %entry
  ret void
}

; As long as the test dominates the backedge, we're good
define void @test3(i64 %start) {
; CHECK-LABEL: @test3
entry:
  br label %loop

loop:
  %indvars.iv = phi i64 [ %start, %entry ], [ %indvars.iv.next, %backedge ]
  %indvars.iv.next = add nsw i64 %indvars.iv, 1
  %cmp = icmp eq i64 %indvars.iv.next, 25
  br i1 %cmp, label %backedge, label %for.end

backedge:
  ; prevent flattening, needed to make sure we're testing what we intend
  call void @foo() 
; CHECK: %cmp1 = icmp slt i64 %start, -1
  %cmp1 = icmp slt i64 %indvars.iv, -1
  br i1 %cmp1, label %for.end, label %loop

for.end:                                          ; preds = %if.end, %entry
  ret void
}

define void @test4(i64 %start) {
; CHECK-LABEL: @test4
entry:
  br label %loop

loop:
  %indvars.iv = phi i64 [ %start, %entry ], [ %indvars.iv.next, %backedge ]
  %indvars.iv.next = add nsw i64 %indvars.iv, 1
  %cmp = icmp eq i64 %indvars.iv.next, 25
  br i1 %cmp, label %backedge, label %for.end

backedge:
  ; prevent flattening, needed to make sure we're testing what we intend
  call void @foo() 
; CHECK: %cmp1 = icmp sgt i64 %start, -1
  %cmp1 = icmp sgt i64 %indvars.iv, -1
  br i1 %cmp1, label %loop, label %for.end

for.end:                                          ; preds = %if.end, %entry
  ret void
}

define void @test5(i64 %start) {
; CHECK-LABEL: @test5
entry:
  br label %loop

loop:
  %indvars.iv = phi i64 [ %start, %entry ], [ %indvars.iv.next, %backedge ]
  %indvars.iv.next = add nuw i64 %indvars.iv, 1
  %cmp = icmp eq i64 %indvars.iv.next, 25
  br i1 %cmp, label %backedge, label %for.end

backedge:
  ; prevent flattening, needed to make sure we're testing what we intend
  call void @foo() 
; CHECK: %cmp1 = icmp ugt i64 %start, 100
  %cmp1 = icmp ugt i64 %indvars.iv, 100
  br i1 %cmp1, label %loop, label %for.end

for.end:                                          ; preds = %if.end, %entry
  ret void
}

define void @test6(i64 %start) {
; CHECK-LABEL: @test6
entry:
  br label %loop

loop:
  %indvars.iv = phi i64 [ %start, %entry ], [ %indvars.iv.next, %backedge ]
  %indvars.iv.next = add nuw i64 %indvars.iv, 1
  %cmp = icmp eq i64 %indvars.iv.next, 25
  br i1 %cmp, label %backedge, label %for.end

backedge:
  ; prevent flattening, needed to make sure we're testing what we intend
  call void @foo() 
; CHECK: %cmp1 = icmp ult i64 %start, 100
  %cmp1 = icmp ult i64 %indvars.iv, 100
  br i1 %cmp1, label %for.end, label %loop

for.end:                                          ; preds = %if.end, %entry
  ret void
}

define void @test7(i64 %start, i64* %inc_ptr) {
; CHECK-LABEL: @test7
entry:
  %inc = load i64, i64* %inc_ptr, !range !0
  %ok = icmp sge i64 %inc, 0
  br i1 %ok, label %loop, label %for.end

loop:
  %indvars.iv = phi i64 [ %start, %entry ], [ %indvars.iv.next, %loop ]
  %indvars.iv.next = add nsw i64 %indvars.iv, %inc
; CHECK: %cmp1 = icmp slt i64 %start, -1
  %cmp1 = icmp slt i64 %indvars.iv, -1
  br i1 %cmp1, label %for.end, label %loop

for.end:                                          ; preds = %if.end, %entry
  ret void
}

!0 = !{i64 0, i64 100}

; Negative test - we can't show that the internal branch executes, so we can't
; fold the test to a loop invariant one.
define void @test1_neg(i64 %start) {
; CHECK-LABEL: @test1_neg
entry:
  br label %loop

loop:
  %indvars.iv = phi i64 [ %start, %entry ], [ %indvars.iv.next, %backedge ]
  %indvars.iv.next = add nsw i64 %indvars.iv, 1
  %cmp = icmp eq i64 %indvars.iv.next, 25
  br i1 %cmp, label %backedge, label %skip
skip:
  ; prevent flattening, needed to make sure we're testing what we intend
  call void @foo() 
; CHECK: %cmp1 = icmp slt i64 %indvars.iv, -1
  %cmp1 = icmp slt i64 %indvars.iv, -1
  br i1 %cmp1, label %for.end, label %backedge
backedge:
  ; prevent flattening, needed to make sure we're testing what we intend
  call void @foo() 
  br label %loop

for.end:                                          ; preds = %if.end, %entry
  ret void
}

; Slightly subtle version of @test4 where the icmp dominates the backedge,
; but the exit branch doesn't.  
define void @test2_neg(i64 %start) {
; CHECK-LABEL: @test2_neg
entry:
  br label %loop

loop:
  %indvars.iv = phi i64 [ %start, %entry ], [ %indvars.iv.next, %backedge ]
  %indvars.iv.next = add nsw i64 %indvars.iv, 1
  %cmp = icmp eq i64 %indvars.iv.next, 25
; CHECK: %cmp1 = icmp slt i64 %indvars.iv, -1
  %cmp1 = icmp slt i64 %indvars.iv, -1
  br i1 %cmp, label %backedge, label %skip
skip:
  ; prevent flattening, needed to make sure we're testing what we intend
  call void @foo() 
  br i1 %cmp1, label %for.end, label %backedge
backedge:
  ; prevent flattening, needed to make sure we're testing what we intend
  call void @foo() 
  br label %loop

for.end:                                          ; preds = %if.end, %entry
  ret void
}

; The branch has to exit the loop if the condition is true
define void @test3_neg(i64 %start) {
; CHECK-LABEL: @test3_neg
entry:
  br label %loop

loop:
  %indvars.iv = phi i64 [ %start, %entry ], [ %indvars.iv.next, %loop ]
  %indvars.iv.next = add nsw i64 %indvars.iv, 1
; CHECK: %cmp1 = icmp slt i64 %indvars.iv, -1
  %cmp1 = icmp slt i64 %indvars.iv, -1
  br i1 %cmp1, label %loop, label %for.end

for.end:                                          ; preds = %if.end, %entry
  ret void
}

define void @test4_neg(i64 %start) {
; CHECK-LABEL: @test4_neg
entry:
  br label %loop

loop:
  %indvars.iv = phi i64 [ %start, %entry ], [ %indvars.iv.next, %backedge ]
  %indvars.iv.next = add nsw i64 %indvars.iv, 1
  %cmp = icmp eq i64 %indvars.iv.next, 25
  br i1 %cmp, label %backedge, label %for.end

backedge:
  ; prevent flattening, needed to make sure we're testing what we intend
  call void @foo() 
; CHECK: %cmp1 = icmp sgt i64 %indvars.iv, -1
  %cmp1 = icmp sgt i64 %indvars.iv, -1

; %cmp1 can be made loop invariant only if the branch below goes to
; %the header when %cmp1 is true.
  br i1 %cmp1, label %for.end, label %loop

for.end:                                          ; preds = %if.end, %entry
  ret void
}

define void @test5_neg(i64 %start, i64 %inc) {
; CHECK-LABEL: @test5_neg
entry:
  br label %loop

loop:
  %indvars.iv = phi i64 [ %start, %entry ], [ %indvars.iv.next, %loop ]
  %indvars.iv.next = add nsw i64 %indvars.iv, %inc
; CHECK: %cmp1 = icmp slt i64 %indvars.iv, -1
  %cmp1 = icmp slt i64 %indvars.iv, -1
  br i1 %cmp1, label %for.end, label %loop

for.end:                                          ; preds = %if.end, %entry
  ret void
}

define void @test8(i64 %start, i64* %inc_ptr) {
; CHECK-LABEL: @test8
entry:
  %inc = load i64, i64* %inc_ptr, !range !1
  %ok = icmp sge i64 %inc, 0
  br i1 %ok, label %loop, label %for.end

loop:
  %indvars.iv = phi i64 [ %start, %entry ], [ %indvars.iv.next, %loop ]
  %indvars.iv.next = add nsw i64 %indvars.iv, %inc
; CHECK: %cmp1 = icmp slt i64 %indvars.iv, -1
  %cmp1 = icmp slt i64 %indvars.iv, -1
  br i1 %cmp1, label %for.end, label %loop

for.end:                                          ; preds = %if.end, %entry
  ret void
}

; check to handle loops without preheaders, but invariant operands
; (we handle this today by inserting a preheader)
define void @test9(i1 %cnd, i64 %start) {
; CHECK-LABEL: @test9
; CHECK-LABEL: loop.preheader:
entry:
  br i1 %cnd, label %entry1, label %entry2
entry1:
  br label %loop
entry2:
  br label %loop
loop:
  %indvars.iv = phi i64 [ %start, %entry1 ],[ %start, %entry2 ], [ %indvars.iv.next, %loop ]
  %indvars.iv.next = add nsw i64 %indvars.iv, 1
; CHECK: %cmp1 = icmp slt i64 %start, -1
  %cmp1 = icmp slt i64 %indvars.iv, -1
  br i1 %cmp1, label %for.end, label %loop

for.end:                                          ; preds = %if.end, %entry
  ret void
}

; check that we handle conditions with loop invariant operands which
; *aren't* in the header - this is a very rare and fragile case where
; we have a "loop" which is known to run exactly one iteration but
; haven't yet simplified the uses of the IV
define void @test10() {
; CHECK-LABEL: @test10
entry:
  br label %loop

loop:
  %phi1 = phi i32 [ %phi2, %latch ], [ 0, %entry ]
  %dec = add i32 %phi1, -1
  br i1 false, label %left, label %right

left:
  br label %latch

right:
  br label %latch

latch:
  %phi2 = phi i32 [ %phi1, %left ], [ %dec, %right ]
  ; CHECK: %cmp = icmp slt i32 -1, undef
  %cmp = icmp slt i32 %phi2, undef
  br i1 true, label %exit, label %loop

exit:
  ret void
}

!1 = !{i64 -1, i64 100}


declare void @foo()