[Assembler] Enable nicer diagnostics for inline assembly.

Summary:
Enables source location in diagnostic messages from the backend.  This
is after parsing, during finalization.  This requires the SourceMgr, the
inline assembly string buffer, and DiagInfo to still be alive after
EmitInlineAsm returns.

This patch creates a single SourceMgr for inline assembly inside the
AsmPrinter.  MCContext gets a pointer to this SourceMgr.  Using one
SourceMgr per call to EmitInlineAsm would make it difficult for
MCContext to figure out in which SourceMgr the SMLoc is located, while a
single SourceMgr can figure it out if it has multiple buffers.

The Str argument to EmitInlineAsm is copied into a buffer and owned by
the inline asm SourceMgr.  This ensures that DiagHandlers won't print
garbage.  (Clang emits a "note: instantiated into assembly here", which
refers to this string.)

The AsmParser gets destroyed before finalization, which means that the
DiagHandlers the AsmParser installs into the SourceMgr will be stale.
Restore the saved DiagHandlers.

Since now we're using just one SourceMgr for multiple inline asm
strings, we need to tell the AsmParser which buffer it needs to parse
currently.  Hand a buffer id -- returned from SourceMgr::
AddNewSourceBuffer -- to the AsmParser.

Reviewers: rnk, grosbach, compnerd, rengolin, rovka, anemet

Reviewed By: rnk

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D29441


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294433 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/AsmPrinter.h

@@ -23,6 +23,7 @@
 #include "llvm/IR/InlineAsm.h"
 #include "llvm/Support/DataTypes.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/SourceMgr.h"
 
 namespace llvm {
 class AsmPrinterHandler;
@@ -137,6 +138,19 @@ class AsmPrinter : public MachineFunctionPass {
   /// maintains ownership of the emitters.
   SmallVector<HandlerInfo, 1> Handlers;
 
+public:
+  struct SrcMgrDiagInfo {
+    SourceMgr SrcMgr;
+    const MDNode *LocInfo;
+    LLVMContext::InlineAsmDiagHandlerTy DiagHandler;
+    void *DiagContext;
+  };
+
+private:
+  /// Structure for generating diagnostics for inline assembly. Only initialised
+  /// when necessary.
+  mutable std::unique_ptr<SrcMgrDiagInfo> DiagInfo;
+
   /// If the target supports dwarf debug info, this pointer is non-null.
   DwarfDebug *DD;
 

include/llvm/MC/MCContext.h

@@ -59,6 +59,9 @@ namespace llvm {
     /// The SourceMgr for this object, if any.
     const SourceMgr *SrcMgr;
 
+    /// The SourceMgr for inline assembly, if any.
+    SourceMgr *InlineSrcMgr;
+
     /// The MCAsmInfo for this target.
     const MCAsmInfo *MAI;
 
@@ -243,6 +246,8 @@ namespace llvm {
 
     const SourceMgr *getSourceManager() const { return SrcMgr; }
 
+    void setInlineSourceManager(SourceMgr *SM) { InlineSrcMgr = SM; }
+
     const MCAsmInfo *getAsmInfo() const { return MAI; }
 
     const MCRegisterInfo *getRegisterInfo() const { return MRI; }

include/llvm/MC/MCParser/MCAsmParser.h

@@ -259,7 +259,7 @@ class MCAsmParser {
 
 /// \brief Create an MCAsmParser instance.
 MCAsmParser *createMCAsmParser(SourceMgr &, MCContext &, MCStreamer &,
-                               const MCAsmInfo &);
+                               const MCAsmInfo &, unsigned CB = 0);
 
 } // end namespace llvm
 

lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp

@@ -40,19 +40,12 @@ using namespace llvm;
 
 #define DEBUG_TYPE "asm-printer"
 
-namespace {
-  struct SrcMgrDiagInfo {
-    const MDNode *LocInfo;
-    LLVMContext::InlineAsmDiagHandlerTy DiagHandler;
-    void *DiagContext;
-  };
-}
-
 /// srcMgrDiagHandler - This callback is invoked when the SourceMgr for an
 /// inline asm has an error in it.  diagInfo is a pointer to the SrcMgrDiagInfo
 /// struct above.
 static void srcMgrDiagHandler(const SMDiagnostic &Diag, void *diagInfo) {
-  SrcMgrDiagInfo *DiagInfo = static_cast<SrcMgrDiagInfo *>(diagInfo);
+  AsmPrinter::SrcMgrDiagInfo *DiagInfo =
+      static_cast<AsmPrinter::SrcMgrDiagInfo *>(diagInfo);
   assert(DiagInfo && "Diagnostic context not passed down?");
 
   // If the inline asm had metadata associated with it, pull out a location
@@ -99,35 +92,34 @@ void AsmPrinter::EmitInlineAsm(StringRef Str, const MCSubtargetInfo &STI,
     return;
   }
 
-  SourceMgr SrcMgr;
-  SrcMgr.setIncludeDirs(MCOptions.IASSearchPaths);
+  if (!DiagInfo) {
+    DiagInfo = make_unique<SrcMgrDiagInfo>();
 
-  SrcMgrDiagInfo DiagInfo;
-
-  // If the current LLVMContext has an inline asm handler, set it in SourceMgr.
-  LLVMContext &LLVMCtx = MMI->getModule()->getContext();
-  bool HasDiagHandler = false;
-  if (LLVMCtx.getInlineAsmDiagnosticHandler() != nullptr) {
-    // If the source manager has an issue, we arrange for srcMgrDiagHandler
-    // to be invoked, getting DiagInfo passed into it.
-    DiagInfo.LocInfo = LocMDNode;
-    DiagInfo.DiagHandler = LLVMCtx.getInlineAsmDiagnosticHandler();
-    DiagInfo.DiagContext = LLVMCtx.getInlineAsmDiagnosticContext();
-    SrcMgr.setDiagHandler(srcMgrDiagHandler, &DiagInfo);
-    HasDiagHandler = true;
+    MCContext &Context = MMI->getContext();
+    Context.setInlineSourceManager(&DiagInfo->SrcMgr);
+
+    LLVMContext &LLVMCtx = MMI->getModule()->getContext();
+    if (LLVMCtx.getInlineAsmDiagnosticHandler()) {
+      DiagInfo->DiagHandler = LLVMCtx.getInlineAsmDiagnosticHandler();
+      DiagInfo->DiagContext = LLVMCtx.getInlineAsmDiagnosticContext();
+      DiagInfo->SrcMgr.setDiagHandler(srcMgrDiagHandler, DiagInfo.get());
+    }
   }
 
+  SourceMgr &SrcMgr = DiagInfo->SrcMgr;
+  SrcMgr.setIncludeDirs(MCOptions.IASSearchPaths);
+  DiagInfo->LocInfo = LocMDNode;
+
   std::unique_ptr<MemoryBuffer> Buffer;
-  if (isNullTerminated)
-    Buffer = MemoryBuffer::getMemBuffer(Str, "<inline asm>");
-  else
-    Buffer = MemoryBuffer::getMemBufferCopy(Str, "<inline asm>");
+  // The inline asm source manager will outlive Str, so make a copy of the
+  // string for SourceMgr to own.
+  Buffer = MemoryBuffer::getMemBufferCopy(Str, "<inline asm>");
 
   // Tell SrcMgr about this buffer, it takes ownership of the buffer.
-  SrcMgr.AddNewSourceBuffer(std::move(Buffer), SMLoc());
+  unsigned BufNum = SrcMgr.AddNewSourceBuffer(std::move(Buffer), SMLoc());
 
   std::unique_ptr<MCAsmParser> Parser(
-      createMCAsmParser(SrcMgr, OutContext, *OutStreamer, *MAI));
+      createMCAsmParser(SrcMgr, OutContext, *OutStreamer, *MAI, BufNum));
 
   // We create a new MCInstrInfo here since we might be at the module level
   // and not have a MachineFunction to initialize the TargetInstrInfo from and
@@ -151,7 +143,13 @@ void AsmPrinter::EmitInlineAsm(StringRef Str, const MCSubtargetInfo &STI,
   int Res = Parser->Run(/*NoInitialTextSection*/ true,
                         /*NoFinalize*/ true);
   emitInlineAsmEnd(STI, &TAP->getSTI());
-  if (Res && !HasDiagHandler)
+
+  // LocInfo cannot be used for error generation from the backend.
+  // FIXME: associate LocInfo with the SourceBuffer to improve backend
+  // messages.
+  DiagInfo->LocInfo = nullptr;
+
+  if (Res && !DiagInfo->DiagHandler)
     report_fatal_error("Error parsing inline asm\n");
 }
 

lib/MC/MCContext.cpp

@@ -521,13 +521,15 @@ CodeViewContext &MCContext::getCVContext() {
 void MCContext::reportError(SMLoc Loc, const Twine &Msg) {
   HadError = true;
 
-  // If we have a source manager use it. Otherwise just use the generic
-  // report_fatal_error().
-  if (!SrcMgr)
+  // If we have a source manager use it. Otherwise, try using the inline source
+  // manager.
+  // If that fails, use the generic report_fatal_error().
+  if (SrcMgr)
+    SrcMgr->PrintMessage(Loc, SourceMgr::DK_Error, Msg);
+  else if (InlineSrcMgr)
+    InlineSrcMgr->PrintMessage(Loc, SourceMgr::DK_Error, Msg);
+  else
     report_fatal_error(Msg, false);
-
-  // Use the source manager to print the message.
-  SrcMgr->PrintMessage(Loc, SourceMgr::DK_Error, Msg);
 }
 
 void MCContext::reportFatalError(SMLoc Loc, const Twine &Msg) {

lib/MC/MCParser/AsmParser.cpp

@@ -209,7 +209,7 @@ class AsmParser : public MCAsmParser {
 
 public:
   AsmParser(SourceMgr &SM, MCContext &Ctx, MCStreamer &Out,
-            const MCAsmInfo &MAI);
+            const MCAsmInfo &MAI, unsigned CB);
   ~AsmParser() override;
 
   bool Run(bool NoInitialTextSection, bool NoFinalize = false) override;
@@ -572,9 +572,9 @@ extern MCAsmParserExtension *createCOFFAsmParser();
 enum { DEFAULT_ADDRSPACE = 0 };
 
 AsmParser::AsmParser(SourceMgr &SM, MCContext &Ctx, MCStreamer &Out,
-                     const MCAsmInfo &MAI)
+                     const MCAsmInfo &MAI, unsigned CB = 0)
     : Lexer(MAI), Ctx(Ctx), Out(Out), MAI(MAI), SrcMgr(SM),
-      PlatformParser(nullptr), CurBuffer(SM.getMainFileID()),
+      PlatformParser(nullptr), CurBuffer(CB ? CB : SM.getMainFileID()),
       MacrosEnabledFlag(true), CppHashInfo(), AssemblerDialect(~0U),
       IsDarwin(false), ParsingInlineAsm(false) {
   HadError = false;
@@ -608,6 +608,10 @@ AsmParser::AsmParser(SourceMgr &SM, MCContext &Ctx, MCStreamer &Out,
 AsmParser::~AsmParser() {
   assert((HadError || ActiveMacros.empty()) &&
          "Unexpected active macro instantiation!");
+
+  // Restore the saved diagnostics handler and context for use during
+  // finalization.
+  SrcMgr.setDiagHandler(SavedDiagHandler, SavedDiagContext);
 }
 
 void AsmParser::printMacroInstantiations() {
@@ -5520,6 +5524,7 @@ bool parseAssignmentExpression(StringRef Name, bool allow_redef,
 
 /// \brief Create an MCAsmParser instance.
 MCAsmParser *llvm::createMCAsmParser(SourceMgr &SM, MCContext &C,
-                                     MCStreamer &Out, const MCAsmInfo &MAI) {
-  return new AsmParser(SM, C, Out, MAI);
+                                     MCStreamer &Out, const MCAsmInfo &MAI,
+                                     unsigned CB) {
+  return new AsmParser(SM, C, Out, MAI, CB);
 }

test/Assembler/inline-asm-diags.ll

@@ -0,0 +1,9 @@
+; RUN: not llc -filetype=obj < %s 2>&1 -o /dev/null | FileCheck %s
+
+module asm ".word 0x10"
+module asm ".word -bar"
+
+; CHECK: <inline asm>:2:7: error: expected relocatable expression
+
+module asm ".word -foo"
+; CHECK: <inline asm>:3:7: error: expected relocatable expression