[SanitizerCoverage] Add fallback DebugLocation for instrumented calls

When building the kernel with LTO, KCOV & debug information enabled,
multiple inlinable SanitizerCoverage functions require debug information
present.

In such cases we repurpose the InstrumentationIRBuilder that ensures
the necessary debug information is added if necessary.

This has been done analogous to the work for the ThreadSanitizer
in D124937.

Bug: ClangBuiltLinux/linux#1721

Reviewed By: melver

Differential Revision: https://reviews.llvm.org/D155377

Author: Jakob-Koschel

llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp

@@ -803,7 +803,7 @@ void ModuleSanitizerCoverage::InjectCoverageForIndirectCalls(
   assert(Options.TracePC || Options.TracePCGuard ||
          Options.Inline8bitCounters || Options.InlineBoolFlag);
   for (auto *I : IndirCalls) {
-    IRBuilder<> IRB(I);
+    InstrumentationIRBuilder IRB(I);
     CallBase &CB = cast<CallBase>(*I);
     Value *Callee = CB.getCalledOperand();
     if (isa<InlineAsm>(Callee))
@@ -820,7 +820,7 @@ void ModuleSanitizerCoverage::InjectTraceForSwitch(
     Function &, ArrayRef<Instruction *> SwitchTraceTargets) {
   for (auto *I : SwitchTraceTargets) {
     if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
-      IRBuilder<> IRB(I);
+      InstrumentationIRBuilder IRB(I);
       SmallVector<Constant *, 16> Initializers;
       Value *Cond = SI->getCondition();
       if (Cond->getType()->getScalarSizeInBits() >
@@ -858,7 +858,7 @@ void ModuleSanitizerCoverage::InjectTraceForSwitch(
 void ModuleSanitizerCoverage::InjectTraceForDiv(
     Function &, ArrayRef<BinaryOperator *> DivTraceTargets) {
   for (auto *BO : DivTraceTargets) {
-    IRBuilder<> IRB(BO);
+    InstrumentationIRBuilder IRB(BO);
     Value *A1 = BO->getOperand(1);
     if (isa<ConstantInt>(A1)) continue;
     if (!A1->getType()->isIntegerTy())
@@ -876,7 +876,7 @@ void ModuleSanitizerCoverage::InjectTraceForDiv(
 void ModuleSanitizerCoverage::InjectTraceForGep(
     Function &, ArrayRef<GetElementPtrInst *> GepTraceTargets) {
   for (auto *GEP : GepTraceTargets) {
-    IRBuilder<> IRB(GEP);
+    InstrumentationIRBuilder IRB(GEP);
     for (Use &Idx : GEP->indices())
       if (!isa<ConstantInt>(Idx) && Idx->getType()->isIntegerTy())
         IRB.CreateCall(SanCovTraceGepFunction,
@@ -898,7 +898,7 @@ void ModuleSanitizerCoverage::InjectTraceForLoadsAndStores(
   Type *PointerType[5] = {Int8PtrTy, Int16PtrTy, Int32PtrTy, Int64PtrTy,
                           Int128PtrTy};
   for (auto *LI : Loads) {
-    IRBuilder<> IRB(LI);
+    InstrumentationIRBuilder IRB(LI);
     auto Ptr = LI->getPointerOperand();
     int Idx = CallbackIdx(LI->getType());
     if (Idx < 0)
@@ -907,7 +907,7 @@ void ModuleSanitizerCoverage::InjectTraceForLoadsAndStores(
                    IRB.CreatePointerCast(Ptr, PointerType[Idx]));
   }
   for (auto *SI : Stores) {
-    IRBuilder<> IRB(SI);
+    InstrumentationIRBuilder IRB(SI);
     auto Ptr = SI->getPointerOperand();
     int Idx = CallbackIdx(SI->getValueOperand()->getType());
     if (Idx < 0)
@@ -921,7 +921,7 @@ void ModuleSanitizerCoverage::InjectTraceForCmp(
     Function &, ArrayRef<Instruction *> CmpTraceTargets) {
   for (auto *I : CmpTraceTargets) {
     if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) {
-      IRBuilder<> IRB(ICMP);
+      InstrumentationIRBuilder IRB(ICMP);
       Value *A0 = ICMP->getOperand(0);
       Value *A1 = ICMP->getOperand(1);
       if (!A0->getType()->isIntegerTy())

llvm/test/Instrumentation/SanitizerCoverage/missing_dbg.ll

@@ -0,0 +1,50 @@
+; RUN: opt < %s -passes='module(sancov-module)' -sanitizer-coverage-level=2 -S | FileCheck %s
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+
+define i32 @with_dbg(ptr %a, ptr %b) !dbg !3 {
+entry:
+  %tmp1 = load i32, ptr %a, align 4
+  %cmp = icmp eq i32 %tmp1, 42
+  br i1 %cmp, label %0, label %1
+0:
+  store i32 %tmp1, ptr %b
+  br label %1
+1:
+  ret i32 %tmp1
+}
+; CHECK-LABEL: @with_dbg
+; CHECK-NEXT:  entry:
+; CHECK:       call void @__sanitizer_cov_trace_pc_guard(ptr @__sancov_gen_) #1, !dbg [[DBG1:![0-9]+]]
+; CHECK:       call void @__sanitizer_cov_trace_pc_guard(ptr inttoptr (i64 add (i64 ptrtoint (ptr @__sancov_gen_ to i64), i64 4) to ptr)) #1, !dbg [[DBG2:![0-9]+]]
+
+define i32 @without_dbg(ptr %a, ptr %b) {
+entry:
+  %tmp1 = load i32, ptr %a, align 4
+  %cmp = icmp eq i32 %tmp1, 42
+  br i1 %cmp, label %0, label %1
+0:
+  store i32 %tmp1, ptr %b
+  br label %1
+1:
+  ret i32 %tmp1
+}
+; CHECK-LABEL: @without_dbg
+; CHECK-NEXT:  entry:
+; CHECK:       call void @__sanitizer_cov_trace_pc_guard(ptr @__sancov_gen_.1) #1
+; CHECK:       call void @__sanitizer_cov_trace_pc_guard(ptr inttoptr (i64 add (i64 ptrtoint (ptr @__sancov_gen_.1 to i64), i64 4) to ptr)) #1
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C89, file: !1, producer: "", isOptimized: true, runtimeVersion: 0, emissionKind: LineTablesOnly, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "foo.c", directory: "")
+!2 = !{i32 2, !"Debug Info Version", i32 3}
+!3 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 190, type: !4, scopeLine: 192, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized, unit: !0)
+!4 = !DISubroutineType(types: !5)
+!5 = !{}
+!6 = !DILocation(line: 192, scope: !3)
+!7 = !DILocation(line: 0, scope: !3)
+
+; CHECK:       [[DBG1]] = !DILocation(line: 192, scope: !3)
+; CHECK:       [[DBG2]] = !DILocation(line: 0, scope: !3)