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llvm-project/llvm/test/Transforms/LoopVectorize/pr31190.ll

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[LV] Don't panic when encountering the IV of an outer loop. Bail out instead of asserting when we encounter this situation, which can actually happen. The reason the test uses the new PM is that the "bad" phi, incidentally, gets cleaned up by LoopSimplify. But LICM can create this kind of phi and preserve loop simplify form, so the cleanup has no chance to run. This fixes PR31190. We may want to solve this in a less conservative manner, since this phi is actually uniform within the inner loop (or we may want LICM to output a cleaner promotion to begin with). Differential Revision: https://reviews.llvm.org/D28490 llvm-svn: 291589
2017-01-11 03:32:30 +08:00
; RUN: opt -passes='loop-vectorize' -debug -S < %s 2>&1 | FileCheck %s
; REQUIRES: asserts
; This checks we don't crash when the inner loop we're trying to vectorize
; is a SCEV AddRec with respect to an outer loop.
; In this case, the problematic PHI is:
; %0 = phi i32 [ undef, %for.cond1.preheader ], [ %inc54, %for.body3 ]
; Since %inc54 is the IV of the outer loop, and %0 equivalent to it,
; we get the situation described above.
; Code that leads to this situation can look something like:
;
; int a, b[1], c;
; void fn1 ()
; {
; for (; c; c++)
; for (a = 0; a; a++)
; b[c] = 4;
; }
;
; The PHI is an artifact of the register promotion of c.
[LV] Run loop-simplify and LCSSA explicitly instead of "requiring" them This changes the vectorizer to explicitly use the loopsimplify and lcssa utils, instead of "requiring" the transformations as if they were analyses. This is not NFC, since it changes the LCSSA behavior - we no longer run LCSSA for all loops, but rather only for the loops we expect to modify. Differential Revision: https://reviews.llvm.org/D28868 llvm-svn: 292456
2017-01-19 08:42:28 +08:00
; Note that we can no longer get the vectorizer to actually see such PHIs,
; because LV now simplifies the loop internally, but the test is still
; useful as a regression test, and in case loop-simplify behavior changes.
[LV] Don't panic when encountering the IV of an outer loop. Bail out instead of asserting when we encounter this situation, which can actually happen. The reason the test uses the new PM is that the "bad" phi, incidentally, gets cleaned up by LoopSimplify. But LICM can create this kind of phi and preserve loop simplify form, so the cleanup has no chance to run. This fixes PR31190. We may want to solve this in a less conservative manner, since this phi is actually uniform within the inner loop (or we may want LICM to output a cleaner promotion to begin with). Differential Revision: https://reviews.llvm.org/D28490 llvm-svn: 291589
2017-01-11 03:32:30 +08:00
@c = external global i32, align 4
@a = external global i32, align 4
@b = external global [1 x i32], align 4
; CHECK: LV: Not vectorizing: Cannot prove legality.
; CHECK-LABEL: @test
define void @test() {
entry:
%a.promoted2 = load i32, i32* @a, align 1
%c.promoted = load i32, i32* @c, align 1
br label %for.cond1.preheader
for.cond1.preheader: ; preds = %for.cond1.for.inc4_crit_edge, %entry
%inc54 = phi i32 [ %inc5, %for.cond1.for.inc4_crit_edge ], [ %c.promoted, %entry ]
%inc.lcssa3 = phi i32 [ %inc.lcssa, %for.cond1.for.inc4_crit_edge ], [ %a.promoted2, %entry ]
br label %for.body3
for.body3: ; preds = %for.body3, %for.cond1.preheader
%inc1 = phi i32 [ %inc.lcssa3, %for.cond1.preheader ], [ %inc, %for.body3 ]
%0 = phi i32 [ undef, %for.cond1.preheader ], [ %inc54, %for.body3 ]
%idxprom = sext i32 %0 to i64
%arrayidx = getelementptr inbounds [1 x i32], [1 x i32]* @b, i64 0, i64 %idxprom
store i32 4, i32* %arrayidx, align 4
%inc = add nsw i32 %inc1, 1
%tobool2 = icmp eq i32 %inc, 0
br i1 %tobool2, label %for.cond1.for.inc4_crit_edge, label %for.body3
for.cond1.for.inc4_crit_edge: ; preds = %for.body3
%inc.lcssa = phi i32 [ %inc, %for.body3 ]
%.lcssa = phi i32 [ %inc54, %for.body3 ]
%inc5 = add nsw i32 %.lcssa, 1
br label %for.cond1.preheader
}