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[LoopVectorize] Added address space check when analysing interleaved accesses

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Prevent memory objects of different address spaces to be part of
the same load/store groups when analysing interleaved accesses.

This is fixing pr31900.

Reviewers: HaoLiu, mssimpso, mkuper

Reviewed By: mssimpso, mkuper

Subscribers: llvm-commits, efriedma, mzolotukhin

Differential Revision: https://reviews.llvm.org/D29717

This reverts r295042 (re-applies r295038) with an additional fix for the
buildbot problem.

llvm-svn: 295858
This commit is contained in:
Karl-Johan Karlsson 2017-02-22 18:37:36 +00:00
parent a198aca0c4
commit 8cea2a9fb5
2 changed files with 56 additions and 14 deletions
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33
lib/Transforms/Vectorize/LoopVectorize.cpp
View File

@ -6025,6 +6025,11 @@ void InterleavedAccessInfo::analyzeInterleaving(
if (DesA.Stride != DesB.Stride || DesA.Size != DesB.Size)
continue;
// Ignore A if the memory object of A and B don't belong to the same
// address space
if (getMemInstAddressSpace(A) != getMemInstAddressSpace(B))
continue;
// Calculate the distance from A to B.
const SCEVConstant *DistToB = dyn_cast<SCEVConstant>(
PSE.getSE()->getMinusSCEV(DesA.Scev, DesB.Scev));
@ -6068,35 +6073,35 @@ void InterleavedAccessInfo::analyzeInterleaving(
releaseGroup(Group);
// Remove interleaved groups with gaps (currently only loads) whose memory
// accesses may wrap around. We have to revisit the getPtrStride analysis,
// this time with ShouldCheckWrap=true, since collectConstStrideAccesses does
// accesses may wrap around. We have to revisit the getPtrStride analysis,
// this time with ShouldCheckWrap=true, since collectConstStrideAccesses does
// not check wrapping (see documentation there).
// FORNOW we use Assume=false;
// TODO: Change to Assume=true but making sure we don't exceed the threshold
// FORNOW we use Assume=false;
// TODO: Change to Assume=true but making sure we don't exceed the threshold
// of runtime SCEV assumptions checks (thereby potentially failing to
// vectorize altogether).
// vectorize altogether).
// Additional optional optimizations:
// TODO: If we are peeling the loop and we know that the first pointer doesn't
// TODO: If we are peeling the loop and we know that the first pointer doesn't
// wrap then we can deduce that all pointers in the group don't wrap.
// This means that we can forcefully peel the loop in order to only have to
// check the first pointer for no-wrap. When we'll change to use Assume=true
// This means that we can forcefully peel the loop in order to only have to
// check the first pointer for no-wrap. When we'll change to use Assume=true
// we'll only need at most one runtime check per interleaved group.
//
for (InterleaveGroup *Group : LoadGroups) {
// Case 1: A full group. Can Skip the checks; For full groups, if the wide
// load would wrap around the address space we would do a memory access at
// nullptr even without the transformation.
if (Group->getNumMembers() == Group->getFactor())
// load would wrap around the address space we would do a memory access at
// nullptr even without the transformation.
if (Group->getNumMembers() == Group->getFactor())
continue;
// Case 2: If first and last members of the group don't wrap this implies
// Case 2: If first and last members of the group don't wrap this implies
// that all the pointers in the group don't wrap.
// So we check only group member 0 (which is always guaranteed to exist),
// and group member Factor - 1; If the latter doesn't exist we rely on
// and group member Factor - 1; If the latter doesn't exist we rely on
// peeling (if it is a non-reveresed accsess -- see Case 3).
Value *FirstMemberPtr = getPointerOperand(Group->getMember(0));
if (!getPtrStride(PSE, FirstMemberPtr, TheLoop, Strides, /*Assume=*/false,
if (!getPtrStride(PSE, FirstMemberPtr, TheLoop, Strides, /*Assume=*/false,
/*ShouldCheckWrap=*/true)) {
DEBUG(dbgs() << "LV: Invalidate candidate interleaved group due to "
"first group member potentially pointer-wrapping.\n");

37
test/Transforms/LoopVectorize/AArch64/pr31900.ll Normal file
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@ -0,0 +1,37 @@
; RUN: opt -S -mtriple=aarch64-apple-ios -loop-vectorize -enable-interleaved-mem-accesses -force-vector-width=2 < %s | FileCheck %s
; Reproducer for address space fault in the LoopVectorizer (pr31900). Added
; different sized address space pointers (p:16:16-p4:32:16) to the aarch64
; datalayout to reproduce the fault.
target datalayout = "e-m:e-i64:64-i128:128-n32:64-S128-p:16:16-p4:32:16"
; Check that all the loads are scalarized
; CHECK: load i16, i16*
; CHECK: load i16, i16*
; CHECK: load i16, i16 addrspace(4)*
; CHECK: load i16, i16 addrspace(4)*
%rec1445 = type { i16, i16, i16, i16, i16 }
define void @foo() {
bb1:
br label %bb4
bb4:
%tmp1 = phi i16 [ undef, %bb1 ], [ %_tmp1013, %bb4 ]
%tmp2 = phi %rec1445* [ undef, %bb1 ], [ %_tmp1015, %bb4 ]
%tmp3 = phi %rec1445 addrspace(4)* [ undef, %bb1 ], [ %_tmp1017, %bb4 ]
%0 = getelementptr %rec1445, %rec1445* %tmp2, i16 0, i32 1
%_tmp987 = load i16, i16* %0, align 1
%1 = getelementptr %rec1445, %rec1445 addrspace(4)* %tmp3, i32 0, i32 1
%_tmp993 = load i16, i16 addrspace(4)* %1, align 1
%_tmp1013 = add i16 %tmp1, 1
%_tmp1015 = getelementptr %rec1445, %rec1445* %tmp2, i16 1
%_tmp1017 = getelementptr %rec1445, %rec1445 addrspace(4)* %tmp3, i32 1
%_tmp1019 = icmp ult i16 %_tmp1013, 24
br i1 %_tmp1019, label %bb4, label %bb16
bb16:
unreachable
}