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4b4709686d
Summary: This hopefully fixes PR28825. The problem now was that a value from the original loop was used in a subloop, which became a sibling after separation. While a subloop doesn't need an lcssa phi node, a sibling does, and that's where we broke LCSSA. The most natural way to fix this now is to simply call formLCSSA on the original loop: it'll do what we've been doing before plus it'll cover situations described above. I think we don't need to run formLCSSARecursively here, and we have an assert to verify this (I've tried testing it on LLVM testsuite + SPECs). I'd be happy to be corrected here though. I also changed a run line in the test from '-lcssa -loop-unroll' to '-lcssa -loop-simplify -indvars', because it exercises LCSSA preservation to the same extent, but also makes less unrelated transformation on the CFG, which makes it easier to verify. Reviewers: chandlerc, sanjoy, silvas Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D23288 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@278173 91177308-0d34-0410-b5e6-96231b3b80d8
140 lines
3.3 KiB
LLVM
140 lines
3.3 KiB
LLVM
; RUN: opt < %s -lcssa -loop-simplify -indvars -S | FileCheck %s
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target triple = "x86_64-unknown-linux-gnu"
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; PR28272, PR28825
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; When LoopSimplify separates nested loops, it might break LCSSA form: values
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; from the original loop might be used in the outer loop. This test invokes
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; loop-unroll, which calls loop-simplify before itself. If LCSSA is broken
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; after loop-simplify, we crash on assertion.
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; CHECK-LABEL: @foo
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define void @foo() {
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entry:
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br label %header
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header:
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br label %loop1
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loop1:
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br i1 true, label %loop1, label %bb43
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bb43:
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%a = phi i32 [ undef, %loop1 ], [ 0, %bb45 ], [ %a, %bb54 ]
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%b = phi i32 [ 0, %loop1 ], [ 1, %bb54 ], [ %c, %bb45 ]
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br i1 true, label %bb114, label %header
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bb114:
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%c = add i32 0, 1
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%d = add i32 0, 1
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br i1 true, label %bb45, label %bb54
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bb45:
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%x = add i32 %d, 0
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br label %bb43
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bb54:
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br label %bb43
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}
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; CHECK-LABEL: @foo2
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define void @foo2() {
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entry:
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br label %outer
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outer.loopexit:
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br label %outer
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outer:
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br label %loop1
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loop1:
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br i1 true, label %loop1, label %loop2.preheader
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loop2.preheader:
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%a.ph = phi i32 [ undef, %loop1 ]
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%b.ph = phi i32 [ 0, %loop1 ]
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br label %loop2
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loop2:
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%a = phi i32 [ 0, %loop2.if.true ], [ %a, %loop2.if.false ], [ %a.ph, %loop2.preheader ], [0, %bb]
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%b = phi i32 [ 1, %loop2.if.false ], [ %c, %loop2.if.true ], [ %b.ph, %loop2.preheader ], [%c, %bb]
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br i1 true, label %loop2.if, label %outer.loopexit
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loop2.if:
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%c = add i32 0, 1
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switch i32 undef, label %loop2.if.false [i32 0, label %loop2.if.true
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i32 1, label %bb]
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loop2.if.true:
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br i1 undef, label %loop2, label %bb
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loop2.if.false:
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br label %loop2
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bb:
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br label %loop2
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}
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; When LoopSimplify separates nested loops, it might break LCSSA form: values
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; from the original loop might be used in exit blocks of the outer loop.
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; CHECK-LABEL: @foo3
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define void @foo3() {
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entry:
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br label %bb1
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bb1:
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br i1 undef, label %bb2, label %bb1
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bb2:
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%a = phi i32 [ undef, %bb1 ], [ %a, %bb3 ], [ undef, %bb5 ]
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br i1 undef, label %bb3, label %bb1
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bb3:
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%b = load i32*, i32** undef
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br i1 undef, label %bb2, label %bb4
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bb4:
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br i1 undef, label %bb5, label %bb6
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bb5:
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br i1 undef, label %bb2, label %bb4
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bb6:
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br i1 undef, label %bb_end, label %bb1
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bb_end:
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%x = getelementptr i32, i32* %b
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br label %bb_end
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}
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; When LoopSimplify separates nested loops, it might break LCSSA form: values
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; from the original loop might occur in a loop, which is now a sibling of the
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; original loop (before separating it was a subloop of the original loop, and
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; thus didn't require an lcssa phi nodes).
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; CHECK-LABEL: @foo4
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define void @foo4() {
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bb1:
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br label %bb2
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; CHECK: bb2.loopexit:
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bb2.loopexit: ; preds = %bb3
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%i.ph = phi i32 [ 0, %bb3 ]
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br label %bb2
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; CHECK: bb2.outer:
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; CHECK: bb2:
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bb2: ; preds = %bb2.loopexit, %bb2, %bb1
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%i = phi i32 [ 0, %bb1 ], [ %i, %bb2 ], [ %i.ph, %bb2.loopexit ]
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%x = load i32, i32* undef, align 8
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br i1 undef, label %bb2, label %bb3.preheader
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; CHECK: bb3.preheader:
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bb3.preheader: ; preds = %bb2
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; CHECK: %x.lcssa = phi i32 [ %x, %bb2 ]
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br label %bb3
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bb3: ; preds = %bb3.preheader, %bb3
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%y = add i32 2, %x
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br i1 true, label %bb2.loopexit, label %bb3
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}
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