[llvm] r207414 - Produce an error instead of a crash in an expr we cannot represent.

[Rafael Espindola]

Author: rafael
Date: Mon Apr 28 07:40:50 2014
New Revision: 207414

URL: http://llvm.org/viewvc/llvm-project?rev=207414&view=rev
Log:
Produce an error instead of a crash in an expr we cannot represent.

Added:
    llvm/trunk/test/MC/ELF/subtraction-error.s
Modified:
    llvm/trunk/lib/MC/ELFObjectWriter.cpp

Modified: llvm/trunk/lib/MC/ELFObjectWriter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/ELFObjectWriter.cpp?rev=207414&r1=207413&r2=207414&view=diff
==============================================================================
--- llvm/trunk/lib/MC/ELFObjectWriter.cpp (original)
+++ llvm/trunk/lib/MC/ELFObjectWriter.cpp Mon Apr 28 07:40:50 2014
@@ -606,7 +606,12 @@ static const MCSymbol *getBaseSymbol(con
   MCValue Value;
   if (!Expr->EvaluateAsRelocatable(Value, &Layout))
     llvm_unreachable("Invalid Expression");
-  assert(!Value.getSymB());
+  const MCSymbolRefExpr *RefB = Value.getSymB();
+  if (RefB) {
+    Layout.getAssembler().getContext().FatalError(
+        SMLoc(), Twine("symbol '") + RefB->getSymbol().getName() +
+                     "' could not be evaluated in a subtraction expression");
+  }
   const MCSymbolRefExpr *A = Value.getSymA();
   if (!A)
     return nullptr;

Added: llvm/trunk/test/MC/ELF/subtraction-error.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/ELF/subtraction-error.s?rev=207414&view=auto
==============================================================================
--- llvm/trunk/test/MC/ELF/subtraction-error.s (added)
+++ llvm/trunk/test/MC/ELF/subtraction-error.s Mon Apr 28 07:40:50 2014
@@ -0,0 +1,8 @@
+// RUN: not llvm-mc -filetype=obj -triple x86_64-pc-linux < %s 2>&1 | FileCheck %s
+
+a:
+    .section foo
+b:
+c = b - a
+
+; CHECK: symbol 'a' could not be evaluated in a subtraction expression