[Assembler] Better error messages for .org directive

Currently, the error messages we emit for the .org directive when the
expression is not absolute or is out of range do not include the line
number of the directive, so it can be hard to track down the problem if
a file contains many .org directives.

This patch stores the source location in the MCOrgFragment, so that it
can be used for diagnostics emitted during layout.

Since layout is an iterative process, and the errors are detected during
each iteration, it would have been possible for errors to be reported
multiple times. To prevent this, I've made the assembler bail out after
each iteration if any errors have been reported. This will still allow
multiple unrelated errors to be reported in the common case where they
are all detected in the first round of layout.

Differential Revision: https://reviews.llvm.org/D27411

llvm-svn: 289643

5 files changed, 32 insertions, 17 deletions

diff --git a/llvm/lib/MC/MCAsmStreamer.cpp b/llvm/lib/MC/MCAsmStreamer.cpp
index e36903e1fae..352219e65a4 100644
--- a/llvm/lib/MC/MCAsmStreamer.cpp
+++ b/llvm/lib/MC/MCAsmStreamer.cpp
@@ -209,7 +209,8 @@ public:
                          unsigned MaxBytesToEmit = 0) override;
 
   void emitValueToOffset(const MCExpr *Offset,
-                         unsigned char Value = 0) override;
+                         unsigned char Value,
+                         SMLoc Loc) override;
 
   void EmitFileDirective(StringRef Filename) override;
   unsigned EmitDwarfFileDirective(unsigned FileNo, StringRef Directory,
@@ -1011,7 +1012,8 @@ void MCAsmStreamer::EmitCodeAlignment(unsigned ByteAlignment,
 }
 
 void MCAsmStreamer::emitValueToOffset(const MCExpr *Offset,
-                                      unsigned char Value) {
+                                      unsigned char Value,
+                                      SMLoc Loc) {
   // FIXME: Verify that Offset is associated with the current section.
   OS << ".org ";
   Offset->print(OS, MAI);
diff --git a/llvm/lib/MC/MCAssembler.cpp b/llvm/lib/MC/MCAssembler.cpp
index 4735f6c3c55..83fcec92e2b 100644
--- a/llvm/lib/MC/MCAssembler.cpp
+++ b/llvm/lib/MC/MCAssembler.cpp
@@ -278,22 +278,29 @@ uint64_t MCAssembler::computeFragmentSize(const MCAsmLayout &Layout,
   case MCFragment::FT_Org: {
     const MCOrgFragment &OF = cast<MCOrgFragment>(F);
     MCValue Value;
-    if (!OF.getOffset().evaluateAsValue(Value, Layout))
-      report_fatal_error("expected assembly-time absolute expression");
+    if (!OF.getOffset().evaluateAsValue(Value, Layout)) {
+      getContext().reportError(OF.getLoc(),
+                               "expected assembly-time absolute expression");
+        return 0;
+    }
 
-    // FIXME: We need a way to communicate this error.
     uint64_t FragmentOffset = Layout.getFragmentOffset(&OF);
     int64_t TargetLocation = Value.getConstant();
     if (const MCSymbolRefExpr *A = Value.getSymA()) {
       uint64_t Val;
-      if (!Layout.getSymbolOffset(A->getSymbol(), Val))
-        report_fatal_error("expected absolute expression");
+      if (!Layout.getSymbolOffset(A->getSymbol(), Val)) {
+        getContext().reportError(OF.getLoc(), "expected absolute expression");
+        return 0;
+      }
       TargetLocation += Val;
     }
     int64_t Size = TargetLocation - FragmentOffset;
-    if (Size < 0 || Size >= 0x40000000)
-      report_fatal_error("invalid .org offset '" + Twine(TargetLocation) +
-                         "' (at offset '" + Twine(FragmentOffset) + "')");
+    if (Size < 0 || Size >= 0x40000000) {
+      getContext().reportError(
+          OF.getLoc(), "invalid .org offset '" + Twine(TargetLocation) +
+                           "' (at offset '" + Twine(FragmentOffset) + "')");
+      return 0;
+    }
     return Size;
   }
 
@@ -660,7 +667,8 @@ void MCAssembler::layout(MCAsmLayout &Layout) {
 
   // Layout until everything fits.
   while (layoutOnce(Layout))
-    continue;
+    if (getContext().hadError())
+      return;
 
   DEBUG_WITH_TYPE("mc-dump", {
       llvm::errs() << "assembler backend - post-relaxation\n--\n";
@@ -912,7 +920,9 @@ bool MCAssembler::layoutOnce(MCAsmLayout &Layout) {
 void MCAssembler::finishLayout(MCAsmLayout &Layout) {
   // The layout is done. Mark every fragment as valid.
   for (unsigned int i = 0, n = Layout.getSectionOrder().size(); i != n; ++i) {
-    Layout.getFragmentOffset(&*Layout.getSectionOrder()[i]->rbegin());
+    MCSection &Section = *Layout.getSectionOrder()[i];
+    Layout.getFragmentOffset(&*Section.rbegin());
+    computeFragmentSize(Layout, *Section.rbegin());
   }
   getBackend().finishLayout(*this, Layout);
 }
diff --git a/llvm/lib/MC/MCObjectStreamer.cpp b/llvm/lib/MC/MCObjectStreamer.cpp
index 123295da15a..cae5c1f8d15 100644
--- a/llvm/lib/MC/MCObjectStreamer.cpp
+++ b/llvm/lib/MC/MCObjectStreamer.cpp
@@ -440,8 +440,9 @@ void MCObjectStreamer::EmitCodeAlignment(unsigned ByteAlignment,
 }
 
 void MCObjectStreamer::emitValueToOffset(const MCExpr *Offset,
-                                         unsigned char Value) {
-  insert(new MCOrgFragment(*Offset, Value));
+                                         unsigned char Value,
+                                         SMLoc Loc) {
+  insert(new MCOrgFragment(*Offset, Value, Loc));
 }
 
 // Associate DTPRel32 fixup with data and resize data area
diff --git a/llvm/lib/MC/MCParser/AsmParser.cpp b/llvm/lib/MC/MCParser/AsmParser.cpp
index 7ebe7b538a2..90a210f364d 100644
--- a/llvm/lib/MC/MCParser/AsmParser.cpp
+++ b/llvm/lib/MC/MCParser/AsmParser.cpp
@@ -2965,6 +2965,7 @@ bool AsmParser::parseDirectiveFill() {
 ///  ::= .org expression [ , expression ]
 bool AsmParser::parseDirectiveOrg() {
   const MCExpr *Offset;
+  SMLoc OffsetLoc = Lexer.getLoc();
   if (checkForValidSection() || parseExpression(Offset))
     return true;
 
@@ -2976,7 +2977,7 @@ bool AsmParser::parseDirectiveOrg() {
   if (parseToken(AsmToken::EndOfStatement))
     return addErrorSuffix(" in '.org' directive");
 
-  getStreamer().emitValueToOffset(Offset, FillExpr);
+  getStreamer().emitValueToOffset(Offset, FillExpr, OffsetLoc);
   return false;
 }
 
@@ -5502,7 +5503,7 @@ bool parseAssignmentExpression(StringRef Name, bool allow_redef,
                           "invalid reassignment of non-absolute variable '" +
                               Name + "'");
   } else if (Name == ".") {
-    Parser.getStreamer().emitValueToOffset(Value, 0);
+    Parser.getStreamer().emitValueToOffset(Value, 0, EqualLoc);
     return false;
   } else
     Sym = Parser.getContext().getOrCreateSymbol(Name);
diff --git a/llvm/lib/MC/MCStreamer.cpp b/llvm/lib/MC/MCStreamer.cpp
index ebbf8116fa3..5cfa3ae80ce 100644
--- a/llvm/lib/MC/MCStreamer.cpp
+++ b/llvm/lib/MC/MCStreamer.cpp
@@ -820,7 +820,8 @@ void MCStreamer::EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
                                       unsigned MaxBytesToEmit) {}
 void MCStreamer::EmitCodeAlignment(unsigned ByteAlignment,
                                    unsigned MaxBytesToEmit) {}
-void MCStreamer::emitValueToOffset(const MCExpr *Offset, unsigned char Value) {}
+void MCStreamer::emitValueToOffset(const MCExpr *Offset, unsigned char Value,
+                                   SMLoc Loc) {}
 void MCStreamer::EmitBundleAlignMode(unsigned AlignPow2) {}
 void MCStreamer::EmitBundleLock(bool AlignToEnd) {}
 void MCStreamer::FinishImpl() {}