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[bpf] Do not expand UNDEF SDNode during insn selection lowering

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o Before this patch, BPF backend will expand UNDEF node
    to i64 constant 0.
  o For second pass of dag combiner, legalizer will run through
    each to-be-processed dag node.
  o If any new SDNode is generated and has an undef operand,
    dag combiner will put undef node, newly-generated constant-0 node,
    and any node which uses these nodes in the working list.
  o During this process, it is possible undef operand is
    generated again, and this will form an infinite loop
    for dag combiner pass2.
  o This patch allows UNDEF to be a legal type.

Signed-off-by: Yonghong Song <yhs@plumgrid.com>
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@249718 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Alexei Starovoitov 2015-10-08 18:52:40 +00:00
parent 8b6e5f368c
commit 08c4d76572
4 changed files with 69 additions and 11 deletions
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7
lib/Target/BPF/BPFISelDAGToDAG.cpp
View File

@ -130,13 +130,6 @@ SDNode *BPFDAGToDAGISel::Select(SDNode *Node) {
// tablegen selection should be handled here.
switch (Opcode) {
default: break;
case ISD::UNDEF: {
errs() << "BUG: "; Node->dump(CurDAG); errs() << '\n';
report_fatal_error("shouldn't see UNDEF during Select");
break;
}
case ISD::INTRINSIC_W_CHAIN: {
unsigned IntNo = cast<ConstantSDNode>(Node->getOperand(1))->getZExtValue();
switch (IntNo) {

3
lib/Target/BPF/BPFISelLowering.cpp
View File

@ -129,9 +129,6 @@ BPFTargetLowering::BPFTargetLowering(const TargetMachine &TM,
setOperationAction(ISD::SUBC, MVT::i64, Expand);
setOperationAction(ISD::SUBE, MVT::i64, Expand);
// no UNDEF allowed
setOperationAction(ISD::UNDEF, MVT::i64, Expand);
setOperationAction(ISD::ROTR, MVT::i64, Expand);
setOperationAction(ISD::ROTL, MVT::i64, Expand);
setOperationAction(ISD::SHL_PARTS, MVT::i64, Expand);

2
test/CodeGen/BPF/sockex2.ll
View File

@ -311,7 +311,7 @@ flow_dissector.exit.thread: ; preds = %86, %12, %196, %199
; CHECK-LABEL: bpf_prog2:
; CHECK: ldabs_h r0, r6.data + 12 # encoding: [0x28,0x00,0x00,0x00,0x0c,0x00,0x00,0x00]
; CHECK: ldabs_h r0, r6.data + 16 # encoding: [0x28,0x00,0x00,0x00,0x10,0x00,0x00,0x00]
; CHECK-NOT: implicit
; CHECK: implicit-def: R1
; CHECK: ld_64 r1
; CHECK-NOT: ori
; CHECK: call 1 # encoding: [0x85,0x00,0x00,0x00,0x01,0x00,0x00,0x00]

68
test/CodeGen/BPF/undef.ll Normal file
View File

@ -0,0 +1,68 @@
; RUN: llc < %s -march=bpf | FileCheck %s
%struct.bpf_map_def = type { i32, i32, i32, i32 }
%struct.__sk_buff = type opaque
%struct.routing_key_2 = type { [6 x i8] }
@routing = global %struct.bpf_map_def { i32 1, i32 6, i32 12, i32 1024 }, section "maps", align 4
@routing_miss_0 = global %struct.bpf_map_def { i32 1, i32 1, i32 12, i32 1 }, section "maps", align 4
@test1 = global %struct.bpf_map_def { i32 2, i32 4, i32 8, i32 1024 }, section "maps", align 4
@test1_miss_4 = global %struct.bpf_map_def { i32 2, i32 1, i32 8, i32 1 }, section "maps", align 4
@_license = global [4 x i8] c"GPL\00", section "license", align 1
@llvm.used = appending global [6 x i8*] [i8* getelementptr inbounds ([4 x i8], [4 x i8]* @_license, i32 0, i32 0), i8* bitcast (i32 (%struct.__sk_buff*)* @ebpf_filter to i8*), i8* bitcast (%struct.bpf_map_def* @routing to i8*), i8* bitcast (%struct.bpf_map_def* @routing_miss_0 to i8*), i8* bitcast (%struct.bpf_map_def* @test1 to i8*), i8* bitcast (%struct.bpf_map_def* @test1_miss_4 to i8*)], section "llvm.metadata"
; Function Attrs: nounwind uwtable
define i32 @ebpf_filter(%struct.__sk_buff* nocapture readnone %ebpf_packet) #0 section "socket1" {
%key = alloca %struct.routing_key_2, align 1
%1 = getelementptr inbounds %struct.routing_key_2, %struct.routing_key_2* %key, i64 0, i32 0, i64 0
; CHECK: mov r1, 5
; CHECK: stb -8(r10), r1
store i8 5, i8* %1, align 1
%2 = getelementptr inbounds %struct.routing_key_2, %struct.routing_key_2* %key, i64 0, i32 0, i64 1
; CHECK: mov r1, 6
; CHECK: stb -7(r10), r1
store i8 6, i8* %2, align 1
%3 = getelementptr inbounds %struct.routing_key_2, %struct.routing_key_2* %key, i64 0, i32 0, i64 2
; CHECK: mov r1, 7
; CHECK: stb -6(r10), r1
store i8 7, i8* %3, align 1
%4 = getelementptr inbounds %struct.routing_key_2, %struct.routing_key_2* %key, i64 0, i32 0, i64 3
; CHECK: mov r1, 8
; CHECK: stb -5(r10), r1
store i8 8, i8* %4, align 1
%5 = getelementptr inbounds %struct.routing_key_2, %struct.routing_key_2* %key, i64 0, i32 0, i64 4
; CHECK: mov r1, 9
; CHECK: stb -4(r10), r1
store i8 9, i8* %5, align 1
%6 = getelementptr inbounds %struct.routing_key_2, %struct.routing_key_2* %key, i64 0, i32 0, i64 5
; CHECK: mov r1, 10
; CHECK: stb -3(r10), r1
store i8 10, i8* %6, align 1
%7 = getelementptr inbounds %struct.routing_key_2, %struct.routing_key_2* %key, i64 1, i32 0, i64 0
; CHECK: mov r1, r10
; CHECK: addi r1, -2
; CHECK: mov r2, 0
; CHECK: sth 6(r1), r2
; CHECK: sth 4(r1), r2
; CHECK: sth 2(r1), r2
; CHECK: sth 24(r10), r2
; CHECK: sth 22(r10), r2
; CHECK: sth 20(r10), r2
; CHECK: sth 18(r10), r2
; CHECK: sth 16(r10), r2
; CHECK: sth 14(r10), r2
; CHECK: sth 12(r10), r2
; CHECK: sth 10(r10), r2
; CHECK: sth 8(r10), r2
; CHECK: sth 6(r10), r2
; CHECK: sth -2(r10), r2
; CHECK: sth 26(r10), r2
call void @llvm.memset.p0i8.i64(i8* %7, i8 0, i64 30, i32 1, i1 false)
%8 = call i32 (%struct.bpf_map_def*, %struct.routing_key_2*, ...) bitcast (i32 (...)* @bpf_map_lookup_elem to i32 (%struct.bpf_map_def*, %struct.routing_key_2*, ...)*)(%struct.bpf_map_def* nonnull @routing, %struct.routing_key_2* nonnull %key) #3
ret i32 undef
}
; Function Attrs: nounwind argmemonly
declare void @llvm.memset.p0i8.i64(i8* nocapture, i8, i64, i32, i1) #1
declare i32 @bpf_map_lookup_elem(...) #2