[debuginfo][codeview] avoid using line zero artificial location for traps when emitting codeview

This fixes an issue where the debug locations for Swift traps were dropped in the produced PDB files, as they were pointing to line 0

I validated this on a sample project using WinDbgx, which can now correctly trap on the same line in multiple places

Author: hyp

lib/IRGen/IRGenDebugInfo.cpp

@@ -2661,12 +2661,19 @@ void IRGenDebugInfoImpl::addFailureMessageToCurrentLoc(IRBuilder &Builder,
   else {
     std::string FuncName = "Swift runtime failure: ";
     FuncName += failureMsg;
-    llvm::DIFile *File = getOrCreateFile({}, {});
+    // CodeView consumers do not correctly handle an artificially generated
+    // file, thus use the original location's file as the file for the debug
+    // function, and prevent reuse of this debug function.
+    bool useCompilerGeneratedFile =
+        Opts.DebugInfoFormat != IRGenDebugInfoFormat::CodeView;
+    llvm::DIFile *File =
+        useCompilerGeneratedFile ? getOrCreateFile({}, {}) : TrapLoc->getFile();
     TrapSP = DBuilder.createFunction(
         File, FuncName, StringRef(), File, 0,
         DIFnTy, 0, llvm::DINode::FlagArtificial,
         llvm::DISubprogram::SPFlagDefinition, nullptr, nullptr, nullptr);
-    RuntimeErrorFnCache.insert({failureMsg, llvm::TrackingMDNodeRef(TrapSP)});
+    if (useCompilerGeneratedFile)
+      RuntimeErrorFnCache.insert({failureMsg, llvm::TrackingMDNodeRef(TrapSP)});
   }
 
   ScopeCache[TrapSc] = llvm::TrackingMDNodeRef(TrapSP);
@@ -2675,7 +2682,15 @@ void IRGenDebugInfoImpl::addFailureMessageToCurrentLoc(IRBuilder &Builder,
   assert(parentScopesAreSane(TrapSc) && "parent scope sanity check failed");
 
   // Wrap the existing TrapLoc into the failure function.
-  auto DL = llvm::DILocation::get(IGM.getLLVMContext(), 0, 0, TrapSP, TrapLoc);
+  // Line 0 is invalid in CodeView, so use the line and column from the original
+  // trap location.
+  auto DL = llvm::DILocation::get(
+      IGM.getLLVMContext(),
+      Opts.DebugInfoFormat == IRGenDebugInfoFormat::CodeView ? TrapLoc.getLine()
+                                                             : 0,
+      Opts.DebugInfoFormat == IRGenDebugInfoFormat::CodeView ? TrapLoc.getCol()
+                                                             : 0,
+      TrapSP, TrapLoc);
   Builder.SetCurrentDebugLocation(DL);
 }
 

lib/IRGen/IRGenFunction.cpp

@@ -445,6 +445,21 @@ Address IRGenFunction::emitAddressAtOffset(llvm::Value *base, Offset offset,
 
 llvm::CallInst *IRBuilder::CreateNonMergeableTrap(IRGenModule &IGM,
                                                   StringRef failureMsg) {
+  if (IGM.DebugInfo &&
+      IGM.getOptions().DebugInfoFormat == IRGenDebugInfoFormat::CodeView) {
+    auto TrapLoc = getCurrentDebugLocation();
+    // Line 0 is invalid in CodeView, so create a new location that uses the
+    // line and column from the inlined location of the trap, that should
+    // correspond to its original source location.
+    if (TrapLoc.getLine() == 0 && TrapLoc.getInlinedAt()) {
+      auto DL = llvm::DILocation::getDistinct(
+          IGM.getLLVMContext(), TrapLoc.getInlinedAt()->getLine(),
+          TrapLoc.getInlinedAt()->getColumn(), TrapLoc.getScope(),
+          TrapLoc.getInlinedAt());
+      SetCurrentDebugLocation(DL);
+    }
+  }
+
   if (IGM.IRGen.Opts.shouldOptimize()) {
     // Emit unique side-effecting inline asm calls in order to eliminate
     // the possibility that an LLVM optimization or code generation pass

test/DebugInfo/doubleinlines.swift

@@ -12,9 +12,13 @@ func callCondFail(arg: Builtin.Int1, msg: Builtin.RawPointer) {
 
 // CHECK: define hidden swiftcc void @"$s13DoubleInlines12callCondFail3arg3msgyBi1__BptF"{{.*}} !dbg ![[FUNC:.*]] {
 // CHECK: tail call void asm sideeffect "", "n"(i32 0) #3, !dbg ![[SCOPEONE:.*]]
+// CHECK: tail call void @llvm.trap(), !dbg ![[LOCTRAP:.*]]
+
 // CHECK: ![[FUNCSCOPEOTHER:.*]] = distinct !DISubprogram(name: "condFail",{{.*}}
-// CHECK: ![[SCOPEONE]] = !DILocation(line: 0, scope: ![[SCOPETWO:.*]], inlinedAt: ![[SCOPETHREE:.*]])
+// CHECK: ![[SCOPEONE]] = distinct !DILocation(line: 6, scope: ![[SCOPETWO:.*]], inlinedAt: ![[SCOPETHREE:.*]])
 // CHECK: ![[SCOPETHREE]] = !DILocation(line: 6, scope: ![[FUNCSCOPE:.*]])
 // CHECK: ![[FUNCSCOPE:[0-9]+]] = distinct !DILexicalBlock(scope: ![[FUNC]],
+// CHECK: ![[LOCTRAP]] = !DILocation(line: 6, scope: ![[SCOPETRAP:.*]], inlinedAt: ![[SCOPEONE]])
+// CHECK: ![[SCOPETRAP]] = distinct !DISubprogram(name: "Swift runtime failure: unknown program error"
 
 import Builtin

test/DebugInfo/linetable-codeview.swift

@@ -78,11 +78,10 @@ func foo() {
 
 // CHECK-DAG: ![[ADD]] = !DILocation(line: 6, scope:
 // CHECK-DAG: ![[DIV]] = !DILocation(line: 7, scope:
-// FIXME: The location of ``@llvm.trap`` should be in Integers.swift.gyb
-//        instead of being artificial.
-// CHECK: ![[INLINEDADD]] = !DILocation(line: 0, scope: ![[FAILURE_FUNC:[0-9]+]], inlinedAt: ![[INLINELOC:[0-9]+]]
+
+// CHECK: ![[INLINEDADD]] = !DILocation(line: 6, scope: ![[FAILURE_FUNC:[0-9]+]], inlinedAt: ![[INLINELOC:[0-9]+]]
 // CHECK-DAG: !{{.*}} = distinct !DISubprogram(name: "Swift runtime failure: arithmetic overflow", scope: {{.*}}, flags: DIFlagArtificial, spFlags: DISPFlagDefinition, {{.*}})
-// CHECK-DAG: ![[INLINELOC]] = !DILocation(line: 0, scope: !{{[0-9]+}}, inlinedAt: ![[ADD]]
+// CHECK-DAG: ![[INLINELOC]] = distinct !DILocation(line: 6, scope: !{{[0-9]+}}, inlinedAt: ![[ADD]]
 
 // NOTE: These prologue instructions are given artificial line locations for
 //       LLDB, but for CodeView they should have the location of the function