[asan] Set debug location in ASan function prologue.

Most importantly, it gives debug location info to the coverage callback.

This change also removes 2 cases of unnecessary setDebugLoc when IRBuilder
is created with the same debug location.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208767 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Instrumentation/AddressSanitizer.cpp

@@ -620,7 +620,6 @@ void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
         IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
         IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
   }
-  Call->setDebugLoc(MI->getDebugLoc());
   MI->eraseFromParent();
 }
 
@@ -743,7 +742,6 @@ void AddressSanitizer::instrumentMop(Instruction *I, bool UseCalls) {
   if (UseCalls) {
     CallInst *Check =
         IRB.CreateCall2(AsanMemoryAccessCallbackSized[IsWrite], AddrLong, Size);
-    Check->setDebugLoc(I->getDebugLoc());
   } else {
     Value *LastByte = IRB.CreateIntToPtr(
         IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
@@ -1526,12 +1524,23 @@ void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
   }
 }
 
+static DebugLoc getFunctionEntryDebugLocation(Function &F) {
+  BasicBlock::iterator I = F.getEntryBlock().begin(),
+                       E = F.getEntryBlock().end();
+  for (; I != E; ++I)
+    if (!isa<AllocaInst>(I))
+      break;
+  return I->getDebugLoc();
+}
+
 void FunctionStackPoisoner::poisonStack() {
   int StackMallocIdx = -1;
+  DebugLoc EntryDebugLocation = getFunctionEntryDebugLocation(F);
 
   assert(AllocaVec.size() > 0);
   Instruction *InsBefore = AllocaVec[0];
   IRBuilder<> IRB(InsBefore);
+  IRB.SetCurrentDebugLocation(EntryDebugLocation);
 
   SmallVector<ASanStackVariableDescription, 16> SVD;
   SVD.reserve(AllocaVec.size());
@@ -1555,6 +1564,7 @@ void FunctionStackPoisoner::poisonStack() {
   Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
   AllocaInst *MyAlloca =
       new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
+  MyAlloca->setDebugLoc(EntryDebugLocation);
   assert((ClRealignStack & (ClRealignStack - 1)) == 0);
   size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
   MyAlloca->setAlignment(FrameAlignment);
@@ -1575,11 +1585,13 @@ void FunctionStackPoisoner::poisonStack() {
     Instruction *Term = SplitBlockAndInsertIfThen(Cmp, InsBefore, false);
     BasicBlock *CmpBlock = cast<Instruction>(Cmp)->getParent();
     IRBuilder<> IRBIf(Term);
+    IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
     LocalStackBase = IRBIf.CreateCall2(
         AsanStackMallocFunc[StackMallocIdx],
         ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
     BasicBlock *SetBlock = cast<Instruction>(LocalStackBase)->getParent();
     IRB.SetInsertPoint(InsBefore);
+    IRB.SetCurrentDebugLocation(EntryDebugLocation);
     PHINode *Phi = IRB.CreatePHI(IntptrTy, 2);
     Phi->addIncoming(OrigStackBase, CmpBlock);
     Phi->addIncoming(LocalStackBase, SetBlock);

test/Instrumentation/AddressSanitizer/coverage-dbg.ll

@@ -0,0 +1,33 @@
+; Test that coverage instrumentation does not lose debug location.
+
+; RUN: opt < %s -asan -asan-module -asan-coverage=1 -S | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Function Attrs: nounwind readnone uwtable
+define void @_Z1fv() #0 {
+entry:
+  ret void, !dbg !11
+}
+
+; CHECK: call void @__sanitizer_cov(), !dbg !
+
+attributes #0 = { sanitize_address nounwind readnone uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!8, !9}
+!llvm.ident = !{!10}
+
+!0 = metadata !{i32 786449, metadata !1, i32 4, metadata !"clang version 3.5.0 (208682)", i1 true, metadata !"", i32 0, metadata !2, metadata !2, metadata !3, metadata !2, metadata !2, metadata !"", i32 1} ; [ DW_TAG_compile_unit ] [/tmp//tmp/1.cc] [DW_LANG_C_plus_plus]
+!1 = metadata !{metadata !"/tmp/1.cc", metadata !"/tmp"}
+!2 = metadata !{}
+!3 = metadata !{metadata !4}
+!4 = metadata !{i32 786478, metadata !1, metadata !5, metadata !"f", metadata !"f", metadata !"_Z1fv", i32 1, metadata !6, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 true, void ()* @_Z1fv, null, null, metadata !2, i32 1} ; [ DW_TAG_subprogram ] [line 1] [def] [f]
+!5 = metadata !{i32 786473, metadata !1}          ; [ DW_TAG_file_type ] [/tmp//tmp/1.cc]
+!6 = metadata !{i32 786453, i32 0, null, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !7, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!7 = metadata !{null}
+!8 = metadata !{i32 2, metadata !"Dwarf Version", i32 4}
+!9 = metadata !{i32 1, metadata !"Debug Info Version", i32 1}
+!10 = metadata !{metadata !"clang version 3.5.0 (208682)"}
+!11 = metadata !{i32 2, i32 0, metadata !4, null}