[llvm] r356279 - [BPF] handle external global properly

[Yonghong Song via llvm-commits]

Author: yhs
Date: Fri Mar 15 10:39:10 2019
New Revision: 356279

URL: http://llvm.org/viewvc/llvm-project?rev=356279&view=rev
Log:
[BPF] handle external global properly

Previous commit 6bc58e6d3dbd ("[BPF] do not generate unused local/global types")
tried to exclude global variable from type generation. The condition is:
     if (Global.hasExternalLinkage())
       continue;
This is not right. It also excluded initialized globals.

The correct condition (from AssemblyWriter::printGlobal()) is:
  if (!GV->hasInitializer() && GV->hasExternalLinkage())
    Out << "external ";

Let us do the same in BTF type generation. Also added a test for it.

Signed-off-by: Yonghong Song <yhs at fb.com>

Added:
    llvm/trunk/test/CodeGen/BPF/BTF/global-var-inited.ll
Modified:
    llvm/trunk/lib/Target/BPF/BTFDebug.cpp

Modified: llvm/trunk/lib/Target/BPF/BTFDebug.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/BPF/BTFDebug.cpp?rev=356279&r1=356278&r2=356279&view=diff
==============================================================================
--- llvm/trunk/lib/Target/BPF/BTFDebug.cpp (original)
+++ llvm/trunk/lib/Target/BPF/BTFDebug.cpp Fri Mar 15 10:39:10 2019
@@ -751,7 +751,7 @@ void BTFDebug::endModule() {
   const Module *M = MMI->getModule();
   for (const GlobalVariable &Global : M->globals()) {
     // Ignore external globals for now.
-    if (Global.hasExternalLinkage())
+    if (!Global.hasInitializer() && Global.hasExternalLinkage())
       continue;
 
     SmallVector<DIGlobalVariableExpression *, 1> GVs;

Added: llvm/trunk/test/CodeGen/BPF/BTF/global-var-inited.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/BPF/BTF/global-var-inited.ll?rev=356279&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/BPF/BTF/global-var-inited.ll (added)
+++ llvm/trunk/test/CodeGen/BPF/BTF/global-var-inited.ll Fri Mar 15 10:39:10 2019
@@ -0,0 +1,42 @@
+; RUN: llc -march=bpfel -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
+; RUN: llc -march=bpfeb -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
+
+; Source code:
+;   int a = 3;
+; Compilation flag:
+;   clang -target bpf -O2 -g -S -emit-llvm test.c
+
+ at a = dso_local local_unnamed_addr global i32 3, align 4, !dbg !0
+
+; CHECK:             .section        .BTF,"", at progbits
+; CHECK-NEXT:        .short  60319                   # 0xeb9f
+; CHECK-NEXT:        .byte   1
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .long   24
+; CHECK-NEXT:        .long   0
+; CHECK-NEXT:        .long   16
+; CHECK-NEXT:        .long   16
+; CHECK-NEXT:        .long   5
+; CHECK-NEXT:        .long   1                       # BTF_KIND_INT(id = 1)
+; CHECK-NEXT:        .long   16777216                # 0x1000000
+; CHECK-NEXT:        .long   4
+; CHECK-NEXT:        .long   16777248                # 0x1000020
+; CHECK-NEXT:        .byte   0                       # string offset=0
+; CHECK-NEXT:        .ascii  "int"                   # string offset=1
+; CHECK-NEXT:        .byte   0
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!7, !8, !9}
+!llvm.ident = !{!10}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "a", scope: !2, file: !3, line: 1, type: !6, isLocal: false, isDefinition: true)
+!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 8.0.20181009 ", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5, nameTableKind: None)
+!3 = !DIFile(filename: "test.c", directory: "/home/yhs/work/tests/llvm/bug")
+!4 = !{}
+!5 = !{!0}
+!6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!7 = !{i32 2, !"Dwarf Version", i32 4}
+!8 = !{i32 2, !"Debug Info Version", i32 3}
+!9 = !{i32 1, !"wchar_size", i32 4}
+!10 = !{!"clang version 8.0.20181009 "}