4 files changed, 80 insertions, 21 deletions
diff --git a/llvm/lib/IR/DebugInfo.cpp b/llvm/lib/IR/DebugInfo.cpp
index e8c62961eba..18ec7cdfdba 100644
--- a/llvm/lib/IR/DebugInfo.cpp
+++ b/llvm/lib/IR/DebugInfo.cpp
@@ -247,8 +247,20 @@ bool llvm::stripDebugInfo(Function &F) {
     Changed = true;
     F.setSubprogram(nullptr);
   }
+
+  Function *Declare = F.getParent()->getFunction("llvm.dbg.declare");
+  Function *DbgVal = F.getParent()->getFunction("llvm.dbg.value");
   for (BasicBlock &BB : F) {
-    for (Instruction &I : BB) {
+    for (auto II = BB.begin(), End = BB.end(); II != End;) {
+      Instruction &I = *II++; // We may delete the instruction, increment now.
+      // Remove all of the calls to the debugger intrinsics, and remove them
+      // from the module.
+      CallInst *CI = dyn_cast<CallInst>(&I);
+      if (CI && (CI->getCalledFunction() == Declare ||
+                 CI->getCalledFunction() == DbgVal)) {
+        CI->eraseFromParent();
+        Changed = true;
+      }
       if (I.getDebugLoc()) {
         Changed = true;
         I.setDebugLoc(DebugLoc());
@@ -261,26 +273,6 @@ bool llvm::stripDebugInfo(Function &F) {
 bool llvm::StripDebugInfo(Module &M) {
   bool Changed = false;
 
-  // Remove all of the calls to the debugger intrinsics, and remove them from
-  // the module.
-  if (Function *Declare = M.getFunction("llvm.dbg.declare")) {
-    while (!Declare->use_empty()) {
-      CallInst *CI = cast<CallInst>(Declare->user_back());
-      CI->eraseFromParent();
-    }
-    Declare->eraseFromParent();
-    Changed = true;
-  }
-
-  if (Function *DbgVal = M.getFunction("llvm.dbg.value")) {
-    while (!DbgVal->use_empty()) {
-      CallInst *CI = cast<CallInst>(DbgVal->user_back());
-      CI->eraseFromParent();
-    }
-    DbgVal->eraseFromParent();
-    Changed = true;
-  }
-
   for (Module::named_metadata_iterator NMI = M.named_metadata_begin(),
          NME = M.named_metadata_end(); NMI != NME;) {
     NamedMDNode *NMD = &*NMI;
diff --git a/llvm/test/ThinLTO/X86/Inputs/drop-debug-info.bc b/llvm/test/ThinLTO/X86/Inputs/drop-debug-info.bc
new file mode 100644
index 00000000000..fbb1c99c83d
--- /dev/null
+++ b/llvm/test/ThinLTO/X86/Inputs/drop-debug-info.bc
diff --git a/llvm/test/ThinLTO/X86/Inputs/drop-debug-info.ll b/llvm/test/ThinLTO/X86/Inputs/drop-debug-info.ll
new file mode 100644
index 00000000000..82a728e2286
--- /dev/null
+++ b/llvm/test/ThinLTO/X86/Inputs/drop-debug-info.ll
@@ -0,0 +1,47 @@
+; This file is checked-in as a .bc file, because the debug info version is
+; intentionally out-of-date and llvm-as will drop it before writing the bitcode
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.11.0"
+
+
+@argc = global i8 0, align 1
+
+define void @globalfunc() {
+entry:
+  %0 = load i8, i8* @argc, align 1
+  tail call void @llvm.dbg.value(metadata i8 %0, i64 0, metadata !19, metadata !29), !dbg !DILocation(scope: !13)
+  ret void
+}
+
+
+declare void @llvm.dbg.value(metadata, i64, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!22, !23}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, enums: !2, retainedTypes: !3, globals: !20, imports: !2, emissionKind: FullDebug)
+!1 = !DIFile(filename: "test.cpp", directory: "")
+!2 = !{}
+!3 = !{!4}
+!4 = !DICompositeType(tag: DW_TAG_class_type, name: "C", line: 2, size: 8, align: 8, file: !1, elements: !5, identifier: "_ZTS1C")
+!5 = !{!6}
+!6 = !DISubprogram(name: "test", file: !1, scope: !4, type: !7, isDefinition: false)
+!7 = !DISubroutineType(types: !8)
+!8 = !{!9, !10, !11, !11, !11, null}
+!9 = !DIBasicType(encoding: DW_ATE_signed, size: 32, align: 32, name: "int")
+!10 = !DIDerivedType(baseType: !4, tag: DW_TAG_pointer_type, size: 64, align: 64, flags: DIFlagArtificial)
+!11 = !DIBasicType(tag: DW_TAG_base_type, name: "char", size: 8, align: 8, encoding: DW_ATE_signed_char)
+!13 = distinct !DISubprogram(name: "test_with_debug", linkageName: "test_with_debug", line: 6, isLocal: false, isDefinition: true, flags: DIFlagPrototyped, isOptimized: true, unit: !0, scopeLine: 6, file: !1, scope: !14, type: !15, variables: !17)
+!14 = !DIFile(filename: "test.cpp", directory: "")
+!15 = !DISubroutineType(types: !16)
+!16 = !{null}
+!17 = !{!18, !19}
+!18 = !DILocalVariable(name: "c", line: 7, scope: !13, file: !14, type: !4)
+!19 = !DILocalVariable(name: "lc", line: 8, scope: !13, file: !14, type: !11)
+!20 = !{!21}
+!21 = !DIGlobalVariable(name: "argc", line: 1, isLocal: false, isDefinition: true, scope: null, file: !14, type: !11, variable: i8* @argc)
+!22 = !{i32 2, !"Dwarf Version", i32 4}
+!23 = !{i32 2, !"Debug Info Version", i32 0}
+!25 = !DILocation(line: 8, column: 3, scope: !13)
+!29 = !DIExpression()
diff --git a/llvm/test/ThinLTO/X86/drop-debug-info.ll b/llvm/test/ThinLTO/X86/drop-debug-info.ll
new file mode 100644
index 00000000000..f8ed8dff420
--- /dev/null
+++ b/llvm/test/ThinLTO/X86/drop-debug-info.ll
@@ -0,0 +1,20 @@
+; RUN: opt -module-summary %s -o %t.bc
+; RUN: llvm-lto -thinlto-action=thinlink -o %t.index.bc %t.bc %p/Inputs/drop-debug-info.bc
+
+; The imported module has out-of-date debug information, let's make sure we can
+; drop them without crashing when materializing later.
+; RUN: llvm-lto -thinlto-action=import %t.bc -thinlto-index=%t.index.bc -o - | llvm-dis -o - | FileCheck %s
+; CHECK: define available_externally void @globalfunc
+; CHECK-NOT: llvm.dbg.value
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.11.0"
+
+
+define i32 @main() #0 {
+entry:
+  call void (...) @globalfunc()
+  ret i32 0
+}
+
+declare void @globalfunc(...)
+\ No newline at end of file