Alina Sbirlea 6720ed851b [MemorySSA] Avoid adding Phis in the presence of unreachable blocks.
Summary:
If a block has all incoming values with the same MemoryAccess (ignoring
incoming values from unreachable blocks), then use that incoming
MemoryAccess and do not create a Phi in the first place.

Revert IDF work-around added in rL372673; it should not be required unless
the Def inserted is the first in its block.

The patch also cleans up a series of tests, added during the many
iterations on insertDef.

The patch also fixes PR43438.
The same issue that occurs in insertDef with "adding phis, hence the IDF of
Phis is needed", can also occur in fixupDefs: the `getPreviousRecursive`
call only adds Phis walking on the predecessor edges, which means there
may be the case of a Phi added walking the CFG "backwards" which
triggers the needs for an additional Phi in successor blocks.
Such Phis are added during fixupDefs only in the presence of unreachable
blocks.
Hence this highlights the need to avoid adding Phis in blocks with
unreachable predecessors in the first place.

Reviewers: george.burgess.iv

Subscribers: Prazek, sanjoy.google, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D67995

llvm-svn: 372932
2019-09-25 23:24:39 +00:00

105 lines
4.1 KiB
LLVM

; RUN: opt -disable-output -licm -print-memoryssa -enable-mssa-loop-dependency=true < %s 2>&1 | FileCheck %s
target datalayout = "E-m:e-i1:8:16-i8:8:16-i64:64-f128:64-v128:64-a:8:16-n32:64"
target triple = "s390x-ibm-linux"
@g_248 = external dso_local local_unnamed_addr global i32, align 4
@g_976 = external dso_local global i64, align 8
@g_1087 = external dso_local global i32**, align 8
; CHECK-LABEL: @f1()
; CHECK: 5 = MemoryPhi(
; CHECK-NOT: 7 = MemoryPhi(
define dso_local fastcc void @f1() unnamed_addr #0 {
label0:
br i1 undef, label %thread-pre-split.i.preheader, label %label5
thread-pre-split.i.preheader: ; preds = %label0
br label %thread-pre-split.i
thread-pre-split.i.us: ; preds = %.critedge1.i.us
br i1 undef, label %.preheader.i.us.preheader, label %label2
.preheader.i.us.preheader: ; preds = %thread-pre-split.i.us
br label %.preheader.i.us
.preheader.i.us: ; preds = %._crit_edge.i.us, %.preheader.i.us.preheader
br i1 undef, label %.lr.ph.i.us, label %._crit_edge.i.us
.lr.ph.i.us: ; preds = %.preheader.i.us
br label %label1
label1: ; preds = %label1, %.lr.ph.i.us
br i1 undef, label %label1, label %._crit_edge.i.us
._crit_edge.i.us: ; preds = %label1, %.preheader.i.us
br i1 undef, label %.preheader.i.us, label %._crit_edge5.i.us
._crit_edge5.i.us: ; preds = %._crit_edge.i.us
br label %label2
label2: ; preds = %._crit_edge5.i.us, %thread-pre-split.i.us
tail call void @foo16()
br i1 undef, label %.lr.ph8.i.us.preheader, label %label4
.lr.ph8.i.us.preheader: ; preds = %label2
br label %.lr.ph8.i.us
.lr.ph8.i.us: ; preds = %.lr.ph8.i.us, %.lr.ph8.i.us.preheader
%tmp3 = load volatile i64, i64* @g_976, align 8
br i1 undef, label %.lr.ph8.i.us, label %._crit_edge9.i.us
._crit_edge9.i.us: ; preds = %.lr.ph8.i.us
br label %label4
label4: ; preds = %._crit_edge9.i.us, %label2
br i1 true, label %f9.exit, label %.critedge1.i.us
.critedge1.i.us: ; preds = %label4
br i1 undef, label %thread-pre-split.i.us, label %f9.exit
label5: ; preds = %label0
unreachable
thread-pre-split.i: ; preds = %.critedge1.i, %thread-pre-split.i.preheader
br i1 undef, label %.preheader.i.preheader, label %.critedge1.i
.preheader.i.preheader: ; preds = %thread-pre-split.i
br label %.preheader.i
.preheader.i: ; preds = %._crit_edge.i, %.preheader.i.preheader
br i1 undef, label %.lr.ph.i, label %._crit_edge.i
.lr.ph.i: ; preds = %.preheader.i
br label %label6
label6: ; preds = %label6, %.lr.ph.i
br i1 undef, label %label6, label %._crit_edge.i.loopexit
._crit_edge.i.loopexit: ; preds = %label6
br label %._crit_edge.i
._crit_edge.i: ; preds = %._crit_edge.i.loopexit, %.preheader.i
br i1 undef, label %.preheader.i, label %._crit_edge5.i
._crit_edge5.i: ; preds = %._crit_edge.i
br label %.critedge1.i
.critedge1.i: ; preds = %._crit_edge5.i, %thread-pre-split.i
%tmp7 = load i32, i32* @g_248, align 4
%tmp8 = xor i32 %tmp7, 55987
store i32 %tmp8, i32* @g_248, align 4
br i1 undef, label %thread-pre-split.i, label %f9.exit.loopexit
f9.exit.loopexit: ; preds = %.critedge1.i
br label %f9.exit
f9.exit: ; preds = %f9.exit.loopexit, %.critedge1.i.us, %label4
%tmp9 = load volatile i32**, i32*** @g_1087, align 8
ret void
}
declare dso_local void @foo16() local_unnamed_addr #1
attributes #0 = { "target-features"="+transactional-execution,+vector" }
attributes #1 = { "use-soft-float"="false" }