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llvm-mirror/test/Analysis/MemorySSA/pr40754.ll
Alina Sbirlea ec066ddf96 [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

56 lines
2.0 KiB
LLVM

; RUN: opt -licm -enable-mssa-loop-dependency -verify-memoryssa -S < %s | FileCheck %s
; REQUIRES: asserts
target datalayout = "E-m:e-i1:8:16-i8:8:16-i64:64-f128:64-v128:64-a:8:16-n32:64"
target triple = "systemz-unknown"
@g_120 = external dso_local local_unnamed_addr global [8 x [4 x [6 x i32]]], align 4
@g_185 = external dso_local local_unnamed_addr global i32, align 4
@g_329 = external dso_local local_unnamed_addr global i16, align 2
; Function Attrs: norecurse noreturn nounwind
define dso_local void @func_65() local_unnamed_addr {
; CHECK-LABEL: @func_65()
label0:
br label %label1
label1: ; preds = %.thread, %label0
br label %label2
label2: ; preds = %.critedge, %label1
br label %label3
label3: ; preds = %label5, %label2
%storemerge = phi i32 [ 0, %label2 ], [ %tmp6, %label5 ]
store i32 %storemerge, i32* @g_185, align 4
%tmp4 = icmp ult i32 %storemerge, 2
br i1 %tmp4, label %label5, label %.thread.loopexit
label5: ; preds = %label3
%tmp6 = add i32 %storemerge, 1
%tmp7 = zext i32 %tmp6 to i64
%tmp8 = getelementptr [8 x [4 x [6 x i32]]], [8 x [4 x [6 x i32]]]* @g_120, i64 0, i64 undef, i64 %tmp7, i64 undef
%tmp9 = load i32, i32* %tmp8, align 4
%tmp10 = icmp eq i32 %tmp9, 0
br i1 %tmp10, label %label3, label %label11
label11: ; preds = %label5
%storemerge.lcssa4 = phi i32 [ %storemerge, %label5 ]
%tmp12 = icmp eq i32 %storemerge.lcssa4, 0
br i1 %tmp12, label %.critedge, label %.thread.loopexit3
.critedge: ; preds = %label11
store i16 0, i16* @g_329, align 2
br label %label2
.thread.loopexit: ; preds = %label3
br label %.thread
.thread.loopexit3: ; preds = %label11
br label %.thread
.thread: ; preds = %.thread.loopexit3, %.thread.loopexit
br label %label1
}