From f580a6229fc32444134bcc8fcc2fbc4cc756034d Mon Sep 17 00:00:00 2001
From: Keno Fischer <kfischer@college.harvard.edu>
Date: Tue, 22 Dec 2015 07:14:50 +0000
Subject: [PATCH] [ASMPrinter] Fix missing handling of DW_OP_bit_piece

In r256077, I added printing for DIExpressions in DEBUG_VALUE comments,
but neglected to handle DW_OP_bit_piece operands. Thanks to
Mikael Holmen and Joerg Sonnenberger for spotting this.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@256236 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/AsmPrinter/AsmPrinter.cpp |  3 ++
 test/CodeGen/X86/bit-piece-comment.ll | 64 +++++++++++++++++++++++++++
 2 files changed, 67 insertions(+)
 create mode 100644 test/CodeGen/X86/bit-piece-comment.ll

diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 9132b8e1523..73149441935 100644
--- a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -787,6 +787,9 @@ static bool emitDebugValueComment(const MachineInstr *MI, AsmPrinter &AP) {
     if (Op == dwarf::DW_OP_deref) {
       Deref = true;
       continue;
+    } else if (Op == dwarf::DW_OP_bit_piece) {
+      // There can't be any operands after this in a valid expression
+      break;
     }
     uint64_t ExtraOffset = Expr->getElement(i++);
     if (Op == dwarf::DW_OP_plus)
diff --git a/test/CodeGen/X86/bit-piece-comment.ll b/test/CodeGen/X86/bit-piece-comment.ll
new file mode 100644
index 00000000000..6ce858b11dc
--- /dev/null
+++ b/test/CodeGen/X86/bit-piece-comment.ll
@@ -0,0 +1,64 @@
+; RUN: llc -filetype=asm < %s
+;
+; We check that we don't crash when printing assembly comments that include
+; a DW_OP_bit_piece
+;
+; Regenerate from
+; void fn1() {
+; struct {
+;   int dword[2];
+; } u;
+; u.dword[1] = 0;
+; };
+; via clang++ -g -fno-integrated-as -Os
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+
+%struct.anon = type { [2 x i32] }
+
+; Function Attrs: norecurse nounwind optsize readnone uwtable
+define void @_Z3fn1v() #0 !dbg !4 {
+entry:
+  tail call void @llvm.dbg.declare(metadata %struct.anon* undef, metadata !8, metadata !19), !dbg !20
+  tail call void @llvm.dbg.value(metadata i32 0, i64 0, metadata !8, metadata !21), !dbg !20
+  ret void, !dbg !22
+}
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.value(metadata, i64, metadata, metadata) #1
+
+attributes #0 = { norecurse nounwind optsize readnone uwtable "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { nounwind readnone }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!16, !17}
+!llvm.ident = !{!18}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 3.8.0 (trunk 256088) (llvm/trunk 256097)", isOptimized: true, runtimeVersion: 0, emissionKind: 1, enums: !2, subprograms: !3)
+!1 = !DIFile(filename: "test.cpp", directory: "/mnt/extra")
+!2 = !{}
+!3 = !{!4}
+!4 = distinct !DISubprogram(name: "fn1", linkageName: "_Z3fn1v", scope: !1, file: !1, line: 1, type: !5, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: true, variables: !7)
+!5 = !DISubroutineType(types: !6)
+!6 = !{null}
+!7 = !{!8}
+!8 = !DILocalVariable(name: "u", scope: !4, file: !1, line: 4, type: !9)
+!9 = !DICompositeType(tag: DW_TAG_structure_type, scope: !4, file: !1, line: 2, size: 64, align: 32, elements: !10)
+!10 = !{!11}
+!11 = !DIDerivedType(tag: DW_TAG_member, name: "dword", scope: !9, file: !1, line: 3, baseType: !12, size: 64, align: 32)
+!12 = !DICompositeType(tag: DW_TAG_array_type, baseType: !13, size: 64, align: 32, elements: !14)
+!13 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
+!14 = !{!15}
+!15 = !DISubrange(count: 2)
+!16 = !{i32 2, !"Dwarf Version", i32 4}
+!17 = !{i32 2, !"Debug Info Version", i32 3}
+!18 = !{!"clang version 3.8.0 (trunk 256088) (llvm/trunk 256097)"}
+!19 = !DIExpression()
+!20 = !DILocation(line: 4, column: 5, scope: !4)
+!21 = !DIExpression(DW_OP_bit_piece, 32, 32)
+!22 = !DILocation(line: 6, column: 1, scope: !4)
-- 
2.34.1