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|
; RUN: opt < %s -S -indvars -loop-unroll -verify-loop-info | FileCheck %s
;
; Unit tests for loop unrolling using ScalarEvolution to compute trip counts.
;
; Indvars is run first to generate an "old" SCEV result. Some unit
; tests may check that SCEV is properly invalidated between passes.
; Completely unroll loops without a canonical IV.
;
; CHECK: @sansCanonical
; CHECK-NOT: phi
; CHECK-NOT: icmp
; CHECK: ret
define i32 @sansCanonical(i32* %base) nounwind {
entry:
br label %while.body
while.body:
%iv = phi i64 [ 10, %entry ], [ %iv.next, %while.body ]
%sum = phi i32 [ 0, %entry ], [ %sum.next, %while.body ]
%iv.next = add i64 %iv, -1
%adr = getelementptr inbounds i32* %base, i64 %iv.next
%tmp = load i32* %adr, align 8
%sum.next = add i32 %sum, %tmp
%iv.narrow = trunc i64 %iv.next to i32
%cmp.i65 = icmp sgt i32 %iv.narrow, 0
br i1 %cmp.i65, label %while.body, label %exit
exit:
ret i32 %sum
}
; SCEV unrolling properly handles loops with multiple exits. In this
; case, the computed trip count based on a canonical IV is *not* for a
; latch block. Canonical unrolling incorrectly unrolls it, but SCEV
; unrolling does not.
;
; CHECK: @earlyLoopTest
; CHECK: tail:
; CHECK-NOT: br
; CHECK: br i1 %cmp2, label %loop, label %exit2
define i64 @earlyLoopTest(i64* %base) nounwind {
entry:
br label %loop
loop:
%iv = phi i64 [ 0, %entry ], [ %inc, %tail ]
%s = phi i64 [ 0, %entry ], [ %s.next, %tail ]
%adr = getelementptr i64* %base, i64 %iv
%val = load i64* %adr
%s.next = add i64 %s, %val
%inc = add i64 %iv, 1
%cmp = icmp ne i64 %inc, 4
br i1 %cmp, label %tail, label %exit1
tail:
%cmp2 = icmp ne i64 %val, 0
br i1 %cmp2, label %loop, label %exit2
exit1:
ret i64 %s
exit2:
ret i64 %s.next
}
; SCEV properly unrolls multi-exit loops.
;
; SCEV cannot currently unroll this loop.
; It should ideally detect a trip count of 5.
; rdar:14038809 [SCEV]: Optimize trip count computation for multi-exit loops.
; CHECK: @multiExit
; CHECKFIXME: getelementptr i32* %base, i32 10
; CHECKFIXME-NEXT: load i32*
; CHECKFIXME: br i1 false, label %l2.10, label %exit1
; CHECKFIXME: l2.10:
; CHECKFIXME-NOT: br
; CHECKFIXME: ret i32
define i32 @multiExit(i32* %base) nounwind {
entry:
br label %l1
l1:
%iv1 = phi i32 [ 0, %entry ], [ %inc1, %l2 ]
%iv2 = phi i32 [ 0, %entry ], [ %inc2, %l2 ]
%inc1 = add i32 %iv1, 1
%inc2 = add i32 %iv2, 1
%adr = getelementptr i32* %base, i32 %iv1
%val = load i32* %adr
%cmp1 = icmp slt i32 %iv1, 5
br i1 %cmp1, label %l2, label %exit1
l2:
%cmp2 = icmp slt i32 %iv2, 10
br i1 %cmp2, label %l1, label %exit2
exit1:
ret i32 1
exit2:
ret i32 %val
}
; SCEV should not unroll a multi-exit loops unless the latch block has
; a known trip count, regardless of the early exit trip counts. The
; LoopUnroll utility uses this assumption to optimize the latch
; block's branch.
;
; CHECK: @multiExit
; CHECK: l3:
; CHECK-NOT: br
; CHECK: br i1 %cmp3, label %l1, label %exit3
define i32 @multiExitIncomplete(i32* %base) nounwind {
entry:
br label %l1
l1:
%iv1 = phi i32 [ 0, %entry ], [ %inc1, %l3 ]
%iv2 = phi i32 [ 0, %entry ], [ %inc2, %l3 ]
%inc1 = add i32 %iv1, 1
%inc2 = add i32 %iv2, 1
%adr = getelementptr i32* %base, i32 %iv1
%val = load i32* %adr
%cmp1 = icmp slt i32 %iv1, 5
br i1 %cmp1, label %l2, label %exit1
l2:
%cmp2 = icmp slt i32 %iv2, 10
br i1 %cmp2, label %l3, label %exit2
l3:
%cmp3 = icmp ne i32 %val, 0
br i1 %cmp3, label %l1, label %exit3
exit1:
ret i32 1
exit2:
ret i32 2
exit3:
ret i32 3
}
; When loop unroll merges a loop exit with one of its parent loop's
; exits, SCEV must forget its ExitNotTaken info.
;
; CHECK: @nestedUnroll
; CHECK-NOT: br i1
; CHECK: for.body87:
define void @nestedUnroll() nounwind {
entry:
br label %for.inc
for.inc:
br i1 false, label %for.inc, label %for.body38.preheader
for.body38.preheader:
br label %for.body38
for.body38:
%i.113 = phi i32 [ %inc76, %for.inc74 ], [ 0, %for.body38.preheader ]
%mul48 = mul nsw i32 %i.113, 6
br label %for.body43
for.body43:
%j.011 = phi i32 [ 0, %for.body38 ], [ %inc72, %for.body43 ]
%add49 = add nsw i32 %j.011, %mul48
%sh_prom50 = zext i32 %add49 to i64
%inc72 = add nsw i32 %j.011, 1
br i1 false, label %for.body43, label %for.inc74
for.inc74:
%inc76 = add nsw i32 %i.113, 1
br i1 false, label %for.body38, label %for.body87.preheader
for.body87.preheader:
br label %for.body87
for.body87:
br label %for.body87
}
; PR16130: clang produces incorrect code with loop/expression at -O2
; rdar:14036816 loop-unroll makes assumptions about undefined behavior
;
; The loop latch is assumed to exit after the first iteration because
; of the induction variable's NSW flag. However, the loop latch's
; equality test is skipped and the loop exits after the second
; iteration via the early exit. So loop unrolling cannot assume that
; the loop latch's exit count of zero is an upper bound on the number
; of iterations.
;
; CHECK: @nsw_latch
; CHECK: for.body:
; CHECK: %b.03 = phi i32 [ 0, %entry ], [ %add, %for.cond ]
; CHECK: return:
; CHECK: %b.03.lcssa = phi i32 [ %b.03, %for.body ], [ %b.03, %for.cond ]
define void @nsw_latch(i32* %a) nounwind {
entry:
br label %for.body
for.body: ; preds = %for.cond, %entry
%b.03 = phi i32 [ 0, %entry ], [ %add, %for.cond ]
%tobool = icmp eq i32 %b.03, 0
%add = add nsw i32 %b.03, 8
br i1 %tobool, label %for.cond, label %return
for.cond: ; preds = %for.body
%cmp = icmp eq i32 %add, 13
br i1 %cmp, label %return, label %for.body
return: ; preds = %for.body, %for.cond
%b.03.lcssa = phi i32 [ %b.03, %for.body ], [ %b.03, %for.cond ]
%retval.0 = phi i32 [ 1, %for.body ], [ 0, %for.cond ]
store i32 %b.03.lcssa, i32* %a, align 4
ret void
}
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