Revert r292204 as it introduces a stack-use-after-scope issue.

[krasin]

Summary

Revert [bpf] error when unknown bpf helper is called

Emit error when BPF backend sees a call to a global function or to an external symbol.
The kernel verifier only allows calls to predefined helpers from bpf.h
which are defined in 'enum bpf_func_id'. Such calls in assembler must
look like 'call [1-9]+' where number matches bpf_func_id.

Example breakage:
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-fast/builds/2170/steps/check-llvm%20asan/logs/stdio

[ast]

unnecessary anymore.

[krasin]

A proper fix had been submitted.

cmake/modules/HandleLLVMOptions.cmake

if (LLVM_ON_UNIX)
     elseif (LLVM_USE_SANITIZER MATCHES "Memory(WithOrigins)?")
       append_common_sanitizer_flags()
       append("-fsanitize=memory" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
       if(LLVM_USE_SANITIZER STREQUAL "MemoryWithOrigins")
         append("-fsanitize-memory-track-origins" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
       endif()
     elseif (LLVM_USE_SANITIZER STREQUAL "Undefined")
       append_common_sanitizer_flags()
-      append("-fsanitize=undefined -fno-sanitize=vptr,function -fno-sanitize-recover=all"
+      append("-fsanitize=undefined -fno-sanitize=vptr,function,null -fno-sanitize-recover=all"
               CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
       append("-fsanitize-blacklist=${CMAKE_SOURCE_DIR}/utils/sanitizers/ubsan_blacklist.txt"
         CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
     elseif (LLVM_USE_SANITIZER STREQUAL "Thread")
       append_common_sanitizer_flags()
       append("-fsanitize=thread" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
     elseif (LLVM_USE_SANITIZER STREQUAL "Address;Undefined" OR
             LLVM_USE_SANITIZER STREQUAL "Undefined;Address")

lib/Target/BPF/BPFISelLowering.cpp

 #include "llvm/IR/DiagnosticPrinter.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 using namespace llvm;
 
 #define DEBUG_TYPE "bpf-lower"
 
-static void fail(const SDLoc &DL, SelectionDAG &DAG, const Twine &Msg) {
+static void fail(const SDLoc &DL, SelectionDAG &DAG, const char *Msg) {
   MachineFunction &MF = DAG.getMachineFunction();
   DAG.getContext()->diagnose(
       DiagnosticInfoUnsupported(*MF.getFunction(), Msg, DL.getDebugLoc()));
 }
 
 static void fail(const SDLoc &DL, SelectionDAG &DAG, const char *Msg,
                  SDValue Val) {
   MachineFunction &MF = DAG.getMachineFunction();
SDValue BPFTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
   for (auto &Reg : RegsToPass) {
     Chain = DAG.getCopyToReg(Chain, CLI.DL, Reg.first, Reg.second, InFlag);
     InFlag = Chain.getValue(1);
   }
 
   // If the callee is a GlobalAddress node (quite common, every direct call is)
   // turn it into a TargetGlobalAddress node so that legalize doesn't hack it.
   // Likewise ExternalSymbol -> TargetExternalSymbol.
-  if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee)) {
-    auto GV = G->getGlobal();
-    Twine Msg("A call to global function '" + StringRef(GV->getName())
-               + "' is not supported. "
-               + (GV->isDeclaration() ?
-                 "Only calls to predefined BPF helpers are allowed." :
-                 "Please use __attribute__((always_inline) to make sure"
-                 " this function is inlined."));
-    fail(CLI.DL, DAG, Msg);
+  if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee))
     Callee = DAG.getTargetGlobalAddress(G->getGlobal(), CLI.DL, PtrVT,
                                         G->getOffset(), 0);
-  } else if (ExternalSymbolSDNode *E = dyn_cast<ExternalSymbolSDNode>(Callee)) {
+  else if (ExternalSymbolSDNode *E = dyn_cast<ExternalSymbolSDNode>(Callee))
     Callee = DAG.getTargetExternalSymbol(E->getSymbol(), PtrVT, 0);
-    fail(CLI.DL, DAG, Twine("A call to built-in function '"
-                            + StringRef(E->getSymbol())
-                            + "' is not supported."));
-  }
 
   // Returns a chain & a flag for retval copy to use.
   SDVTList NodeTys = DAG.getVTList(MVT::Other, MVT::Glue);
   SmallVector<SDValue, 8> Ops;
   Ops.push_back(Chain);
   Ops.push_back(Callee);
 
   // Add argument registers to the end of the list so that they are

lib/Target/BPF/BPFInstrInfo.td

 def : Pat<(BPFWrapper tglobaladdr:$in), (LD_imm64 tglobaladdr:$in)>;
 
 // 0xffffFFFF doesn't fit into simm32, optimize common case
 def : Pat<(i64 (and (i64 GPR:$src), 0xffffFFFF)),
           (SRL_ri (SLL_ri (i64 GPR:$src), 32), 32)>;
 
 // Calls
 def : Pat<(BPFcall tglobaladdr:$dst), (JAL tglobaladdr:$dst)>;
-def : Pat<(BPFcall texternalsym:$dst), (JAL texternalsym:$dst)>;
 def : Pat<(BPFcall imm:$dst), (JAL imm:$dst)>;
 
 // Loads
 def : Pat<(extloadi8  ADDRri:$src), (i64 (LDB ADDRri:$src))>;
 def : Pat<(extloadi16 ADDRri:$src), (i64 (LDH ADDRri:$src))>;
 def : Pat<(extloadi32 ADDRri:$src), (i64 (LDW ADDRri:$src))>;
 
 // Atomics

lib/Target/BPF/BPFMCInstLower.h

 public:
   BPFMCInstLower(MCContext &ctx, AsmPrinter &printer)
       : Ctx(ctx), Printer(printer) {}
   void Lower(const MachineInstr *MI, MCInst &OutMI) const;
 
   MCOperand LowerSymbolOperand(const MachineOperand &MO, MCSymbol *Sym) const;
 
   MCSymbol *GetGlobalAddressSymbol(const MachineOperand &MO) const;
-  MCSymbol *GetExternalSymbolSymbol(const MachineOperand &MO) const;
 };
 }
 
 #endif

lib/Target/BPF/BPFMCInstLower.cpp

 #include "llvm/Support/raw_ostream.h"
 using namespace llvm;
 
 MCSymbol *
 BPFMCInstLower::GetGlobalAddressSymbol(const MachineOperand &MO) const {
   return Printer.getSymbol(MO.getGlobal());
 }
 
-MCSymbol *
-BPFMCInstLower::GetExternalSymbolSymbol(const MachineOperand &MO) const {
-  return Printer.GetExternalSymbolSymbol(MO.getSymbolName());
-}
-
 MCOperand BPFMCInstLower::LowerSymbolOperand(const MachineOperand &MO,
                                              MCSymbol *Sym) const {
 
   const MCExpr *Expr = MCSymbolRefExpr::create(Sym, Ctx);
 
   if (!MO.isJTI() && MO.getOffset())
     llvm_unreachable("unknown symbol op");
 
case MachineOperand::MO_Immediate:
       MCOp = MCOperand::createImm(MO.getImm());
       break;
     case MachineOperand::MO_MachineBasicBlock:
       MCOp = MCOperand::createExpr(
           MCSymbolRefExpr::create(MO.getMBB()->getSymbol(), Ctx));
       break;
     case MachineOperand::MO_RegisterMask:
       continue;
-    case MachineOperand::MO_ExternalSymbol:
-      MCOp = LowerSymbolOperand(MO, GetExternalSymbolSymbol(MO));
-      break;
     case MachineOperand::MO_GlobalAddress:
       MCOp = LowerSymbolOperand(MO, GetGlobalAddressSymbol(MO));
       break;
     }
 
     OutMI.addOperand(MCOp);
   }
 }

test/CodeGen/BPF/cc_args.ll

-; RUN: not llc < %s -march=bpfel -show-mc-encoding | FileCheck %s
+; RUN: llc < %s -march=bpfel -show-mc-encoding | FileCheck %s
 
 define void @test() #0 {
 entry:
 ; CHECK: test:
 
 ; CHECK: r1 = 123 # encoding: [0xb7,0x01,0x00,0x00,0x7b,0x00,0x00,0x00]
 ; CHECK: call f_i16
   call void @f_i16(i16 123)

test/CodeGen/BPF/cc_args_be.ll

-; RUN: not llc < %s -march=bpfeb -show-mc-encoding | FileCheck %s
+; RUN: llc < %s -march=bpfeb -show-mc-encoding | FileCheck %s
 ; test big endian
 
 define void @test() #0 {
 entry:
 ; CHECK: test:
 
 ; CHECK: r1 = 123 # encoding: [0xb7,0x10,0x00,0x00,0x00,0x00,0x00,0x7b]
 ; CHECK: call f_i16

test/CodeGen/BPF/cc_ret.ll

-; RUN: not llc < %s -march=bpfel | FileCheck %s
+; RUN: llc < %s -march=bpfel | FileCheck %s
 
 define void @test() #0 {
 entry:
 ; CHECK: test:
 
 ; CHECK: call f_i16
 ; CHECK: *(u16 *)(r1 + 0) = r0
   %0 = call i16 @f_i16()

test/CodeGen/BPF/fi_ri.ll

-; RUN: not llc < %s -march=bpf | FileCheck %s
+; RUN: llc < %s -march=bpf | FileCheck %s
 
 %struct.key_t = type { i32, [16 x i8] }
 
 ; Function Attrs: nounwind uwtable
 define i32 @test() #0 {
   %key = alloca %struct.key_t, align 4
   %1 = bitcast %struct.key_t* %key to i8*
 ; CHECK: r1 = 0

test/CodeGen/BPF/intrinsics.ll

 ; CHECK: r0 = *(u32 *)skb[123]
 }
 
 declare i64 @llvm.bpf.load.word(i8*, i64) #1
 
 define i32 @ld_pseudo() #0 {
 entry:
   %call = tail call i64 @llvm.bpf.pseudo(i64 2, i64 3)
-  tail call void inttoptr (i64 4 to void (i64, i32)*)(i64 %call, i32 4) #2
+  tail call void @bar(i64 %call, i32 4) #2
   ret i32 0
 ; CHECK-LABEL: ld_pseudo:
 ; CHECK: ld_pseudo r1, 2, 3 # encoding: [0x18,0x21,0x00,0x00,0x03,0x00
 }
 
+declare void @bar(i64, i32) #1
+
 declare i64 @llvm.bpf.pseudo(i64, i64) #2
 
 define i32 @bswap(i64 %a, i64 %b, i64 %c) #0 {
 entry:
   %0 = tail call i64 @llvm.bswap.i64(i64 %a)
   %conv = trunc i64 %b to i32
   %1 = tail call i32 @llvm.bswap.i32(i32 %conv)
   %conv1 = zext i32 %1 to i64

test/CodeGen/BPF/objdump_intrinsics.ll

 ; CHECK: r0 = *(u32 *)skb[123]
 }
 
 declare i64 @llvm.bpf.load.word(i8*, i64) #1
 
 define i32 @ld_pseudo() #0 {
 entry:
   %call = tail call i64 @llvm.bpf.pseudo(i64 2, i64 3)
-  tail call void inttoptr (i64 4 to void (i64, i32)*)(i64 %call, i32 4) #2
+  tail call void @bar(i64 %call, i32 4) #2
   ret i32 0
 ; CHECK-LABEL: ld_pseudo:
 ; CHECK: ld_pseudo r1, 2, 3
 }
 
+declare void @bar(i64, i32) #1
+
 declare i64 @llvm.bpf.pseudo(i64, i64) #2
 
 define i32 @bswap(i64 %a, i64 %b, i64 %c) #0 {
 entry:
   %0 = tail call i64 @llvm.bswap.i64(i64 %a)
   %conv = trunc i64 %b to i32
   %1 = tail call i32 @llvm.bswap.i32(i32 %conv)
   %conv1 = zext i32 %1 to i64

test/CodeGen/BPF/objdump_trivial.ll

 ; RUN: llc -march=bpfel -filetype=obj -o - %s | llvm-objdump -d - | FileCheck %s
 
 ; CHECK: if r2 s> r1 goto
-; CHECK: call 1
-; CHECK: exit
-; CHECK: call 2
+; CHECK: call
 ; CHECK: exit
 
+declare void @a()
+declare void @b()
+
 define void @foo(i32 %a) {
 %b = icmp sgt i32 %a, -1
 br i1 %b, label %x, label %y
 x:
-call void inttoptr (i64 1 to void ()*)()
+call void @a()
 ret void
 y:
-call void inttoptr (i64 2 to void ()*)()
+call void @b()
 ret void
 }

test/CodeGen/BPF/sanity.ll

-; RUN: not llc < %s -march=bpfel | FileCheck %s
+; RUN: llc < %s -march=bpfel | FileCheck %s
 
 @foo_printf.fmt = private unnamed_addr constant [9 x i8] c"hello  \0A\00", align 1
 
 ; Function Attrs: nounwind readnone uwtable
 define i32 @foo_int(i32 %a, i32 %b) #0 {
   %1 = add nsw i32 %b, %a
   ret i32 %1
 ; CHECK-LABEL: foo_int:

test/CodeGen/BPF/undef.ll

-; RUN: not llc < %s -march=bpf | FileCheck %s
+; 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

test/CodeGen/BPF/warn-call.ll

-; RUN: not llc -march=bpfel < %s 2>&1 >/dev/null | FileCheck %s
-
-; CHECK: error: warn_call.c
-; CHECK: built-in function 'memcpy'
-; CHECK: error: warn_call.c
-; CHECK: global function 'foo'
-; CHECK: global function 'bar'
-define i8* @warn(i8* returned, i8*, i64) local_unnamed_addr #0 !dbg !6 {
-  tail call void @llvm.dbg.value(metadata i8* %0, i64 0, metadata !14, metadata !17), !dbg !18
-  tail call void @llvm.dbg.value(metadata i8* %1, i64 0, metadata !15, metadata !17), !dbg !19
-  tail call void @llvm.dbg.value(metadata i64 %2, i64 0, metadata !16, metadata !17), !dbg !20
-  tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* %0, i8* %1, i64 %2, i32 1, i1 false), !dbg !21
-  %4 = tail call i8* @foo(i8* %0, i8* %1, i64 %2) #5, !dbg !22
-  %5 = tail call fastcc i8* @bar(i8* %0), !dbg !23
-  ret i8* %5, !dbg !24
-}
-
-; Function Attrs: argmemonly nounwind
-declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture writeonly, i8* nocapture readonly, i64, i32, i1) #1
-
-declare i8* @foo(i8*, i8*, i64) local_unnamed_addr #2
-
-; Function Attrs: noinline nounwind readnone
-define internal fastcc i8* @bar(i8* readnone returned) unnamed_addr #3 !dbg !25 {
-  tail call void @llvm.dbg.value(metadata i8* null, i64 0, metadata !28, metadata !17), !dbg !30
-  tail call void @llvm.dbg.value(metadata i64 0, i64 0, metadata !29, metadata !17), !dbg !31
-  ret i8* %0, !dbg !32
-}
-
-; Function Attrs: nounwind readnone
-declare void @llvm.dbg.value(metadata, i64, metadata, metadata) #4
-
-!llvm.dbg.cu = !{!0}
-!llvm.module.flags = !{!3, !4}
-!llvm.ident = !{!5}
-
-!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 5.0.0 (trunk 292174) (llvm/trunk 292179)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
-!1 = !DIFile(filename: "warn_call.c", directory: "/w/llvm/bld")
-!2 = !{}
-!3 = !{i32 2, !"Dwarf Version", i32 4}
-!4 = !{i32 2, !"Debug Info Version", i32 3}
-!5 = !{!"clang version 5.0.0 (trunk 292174) (llvm/trunk 292179)"}
-!6 = distinct !DISubprogram(name: "warn", scope: !1, file: !1, line: 4, type: !7, isLocal: false, isDefinition: true, scopeLine: 5, flags: DIFlagPrototyped, isOptimized: true, unit: !0, variables: !13)
-!7 = !DISubroutineType(types: !8)
-!8 = !{!9, !9, !10, !12}
-!9 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: null, size: 64)
-!10 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !11, size: 64)
-!11 = !DIDerivedType(tag: DW_TAG_const_type, baseType: null)
-!12 = !DIBasicType(name: "long unsigned int", size: 64, encoding: DW_ATE_unsigned)
-!13 = !{!14, !15, !16}
-!14 = !DILocalVariable(name: "dst", arg: 1, scope: !6, file: !1, line: 4, type: !9)
-!15 = !DILocalVariable(name: "src", arg: 2, scope: !6, file: !1, line: 4, type: !10)
-!16 = !DILocalVariable(name: "len", arg: 3, scope: !6, file: !1, line: 4, type: !12)
-!17 = !DIExpression()
-!18 = !DILocation(line: 4, column: 18, scope: !6)
-!19 = !DILocation(line: 4, column: 35, scope: !6)
-!20 = !DILocation(line: 4, column: 54, scope: !6)
-!21 = !DILocation(line: 6, column: 2, scope: !6)
-!22 = !DILocation(line: 7, column: 2, scope: !6)
-!23 = !DILocation(line: 8, column: 9, scope: !6)
-!24 = !DILocation(line: 8, column: 2, scope: !6)
-!25 = distinct !DISubprogram(name: "bar", scope: !1, file: !1, line: 2, type: !7, isLocal: true, isDefinition: true, scopeLine: 2, flags: DIFlagPrototyped, isOptimized: true, unit: !0, variables: !26)
-!26 = !{!27, !28, !29}
-!27 = !DILocalVariable(name: "dst", arg: 1, scope: !25, file: !1, line: 2, type: !9)
-!28 = !DILocalVariable(name: "src", arg: 2, scope: !25, file: !1, line: 2, type: !10)
-!29 = !DILocalVariable(name: "len", arg: 3, scope: !25, file: !1, line: 2, type: !12)
-!30 = !DILocation(line: 2, column: 67, scope: !25)
-!31 = !DILocation(line: 2, column: 86, scope: !25)
-!32 = !DILocation(line: 2, column: 93, scope: !25)