[llvm] r240649 - [AsmPrinter] Fix crash in handleIndirectSymViaGOTPCRel

[Bruno Cardoso Lopes]

Author: bruno
Date: Thu Jun 25 10:17:23 2015
New Revision: 240649

URL: http://llvm.org/viewvc/llvm-project?rev=240649&view=rev
Log:
[AsmPrinter] Fix crash in handleIndirectSymViaGOTPCRel

Check for symbols in MCValue before using them. Bail out early in case
they are null. This fixes PR23779.

Differential Revision: http://reviews.llvm.org/D10712

rdar://problem/21532830

Modified:
    llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
    llvm/trunk/test/MC/MachO/cstexpr-gotpcrel-64.ll

Modified: llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp?rev=240649&r1=240648&r2=240649&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp Thu Jun 25 10:17:23 2015
@@ -2086,8 +2086,12 @@ static void handleIndirectSymViaGOTPCRel
   MCValue MV;
   if (!(*ME)->evaluateAsRelocatable(MV, nullptr, nullptr) || MV.isAbsolute())
     return;
+  const MCSymbolRefExpr *SymA = MV.getSymA();
+  if (!SymA)
+    return;
 
-  const MCSymbol *GOTEquivSym = &MV.getSymA()->getSymbol();
+  // Check that GOT equivalent symbol is cached.
+  const MCSymbol *GOTEquivSym = &SymA->getSymbol();
   if (!AP.GlobalGOTEquivs.count(GOTEquivSym))
     return;
 
@@ -2095,8 +2099,11 @@ static void handleIndirectSymViaGOTPCRel
   if (!BaseGV)
     return;
 
+  // Check for a valid base symbol
   const MCSymbol *BaseSym = AP.getSymbol(BaseGV);
-  if (BaseSym != &MV.getSymB()->getSymbol())
+  const MCSymbolRefExpr *SymB = MV.getSymB();
+
+  if (!SymB || BaseSym != &SymB->getSymbol())
     return;
 
   // Make sure to match:

Modified: llvm/trunk/test/MC/MachO/cstexpr-gotpcrel-64.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/MachO/cstexpr-gotpcrel-64.ll?rev=240649&r1=240648&r2=240649&view=diff
==============================================================================
--- llvm/trunk/test/MC/MachO/cstexpr-gotpcrel-64.ll (original)
+++ llvm/trunk/test/MC/MachO/cstexpr-gotpcrel-64.ll Thu Jun 25 10:17:23 2015
@@ -84,3 +84,12 @@ define i32 @t0(i32 %a) {
 define i32** @t1() {
   ret i32** @bargotequiv
 }
+
+; Do not crash when a pattern cannot be matched as a GOT equivalent
+
+ at a = external global i8
+ at b = internal unnamed_addr constant i8* @a
+
+; X86-LABEL: _c:
+; X86:   .quad _b
+ at c = global i8** @b