[Assembler] Make fatal assembler errors non-fatal

Currently, if the assembler encounters an error after parsing (such as an
out-of-range fixup), it reports this as a fatal error, and so stops after the
first error. However, for most of these there is an obvious way to recover
after emitting the error, such as emitting the fixup with a value of zero. This
means that we can report on all of the errors in a file, not just the first
one. MCContext::reportError records the fact that an error was encountered, so
we won't actually emit an object file with the incorrect contents.

Differential Revision: http://reviews.llvm.org/D14717

llvm-svn: 253328

1 files changed, 20 insertions, 10 deletions

diff --git a/llvm/lib/MC/ELFObjectWriter.cpp b/llvm/lib/MC/ELFObjectWriter.cpp
index 230d3d775b1..df7a606a717 100644
--- a/llvm/lib/MC/ELFObjectWriter.cpp
+++ b/llvm/lib/MC/ELFObjectWriter.cpp
@@ -630,28 +630,36 @@ void ELFObjectWriter::recordRelocation(MCAssembler &Asm,
     // In general, ELF has no relocations for -B. It can only represent (A + C)
     // or (A + C - R). If B = R + K and the relocation is not pcrel, we can
     // replace B to implement it: (A - R - K + C)
-    if (IsPCRel)
-      Asm.getContext().reportFatalError(
+    if (IsPCRel) {
+      Asm.getContext().reportError(
           Fixup.getLoc(),
           "No relocation available to represent this relative expression");
+      return;
+    }
 
     const auto &SymB = cast<MCSymbolELF>(RefB->getSymbol());
 
-    if (SymB.isUndefined())
-      Asm.getContext().reportFatalError(
+    if (SymB.isUndefined()) {
+      Asm.getContext().reportError(
           Fixup.getLoc(),
           Twine("symbol '") + SymB.getName() +
               "' can not be undefined in a subtraction expression");
+      return;
+    }
 
     assert(!SymB.isAbsolute() && "Should have been folded");
     const MCSection &SecB = SymB.getSection();
-    if (&SecB != &FixupSection)
-      Asm.getContext().reportFatalError(
+    if (&SecB != &FixupSection) {
+      Asm.getContext().reportError(
           Fixup.getLoc(), "Cannot represent a difference across sections");
+      return;
+    }
 
-    if (::isWeak(SymB))
-      Asm.getContext().reportFatalError(
+    if (::isWeak(SymB)) {
+      Asm.getContext().reportError(
           Fixup.getLoc(), "Cannot represent a subtraction with a weak symbol");
+      return;
+    }
 
     uint64_t SymBOffset = Layout.getSymbolOffset(SymB);
     uint64_t K = SymBOffset - FixupOffset;
@@ -784,8 +792,10 @@ void ELFObjectWriter::computeSymbolTable(
                     Renames.count(&Symbol)))
       continue;
 
-    if (Symbol.isTemporary() && Symbol.isUndefined())
-      Ctx.reportFatalError(SMLoc(), "Undefined temporary");
+    if (Symbol.isTemporary() && Symbol.isUndefined()) {
+      Ctx.reportError(SMLoc(), "Undefined temporary symbol");
+      continue;
+    }
 
     ELFSymbolData MSD;
     MSD.Symbol = cast<MCSymbolELF>(&Symbol);