ARM: fail less catastrophically on invalid Windows input

Windows supports a restricted set of relocations (compared to ARM ELF).  In some
cases, we may end up generating an unsupported relocation.  This can occur with
bad input to the assembler in particular (the frontend should never generate
code that cannot be compiled).  Generate an error rather than just aborting.

The change in the API is driven by the desire to provide a slightly more helpful
message for debugging purposes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226779 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/MC/MCWinCOFFObjectWriter.h

@@ -11,10 +11,11 @@
 #define LLVM_MC_MCWINCOFFOBJECTWRITER_H
 
 namespace llvm {
-  class MCFixup;
-  class MCObjectWriter;
-  class MCValue;
-  class raw_ostream;
+class MCAsmBackend;
+class MCFixup;
+class MCObjectWriter;
+class MCValue;
+class raw_ostream;
 
   class MCWinCOFFObjectTargetWriter {
     virtual void anchor();
@@ -27,9 +28,9 @@ namespace llvm {
     virtual ~MCWinCOFFObjectTargetWriter() {}
 
     unsigned getMachine() const { return Machine; }
-    virtual unsigned getRelocType(const MCValue &Target,
-                                  const MCFixup &Fixup,
-                                  bool IsCrossSection) const = 0;
+    virtual unsigned getRelocType(const MCValue &Target, const MCFixup &Fixup,
+                                  bool IsCrossSection,
+                                  const MCAsmBackend &MAB) const = 0;
     virtual bool recordRelocation(const MCFixup &) const { return true; }
   };
 

lib/MC/WinCOFFObjectWriter.cpp

@@ -737,8 +737,9 @@ void WinCOFFObjectWriter::RecordRelocation(
   ++Reloc.Symb->Relocations;
 
   Reloc.Data.VirtualAddress += Fixup.getOffset();
-  Reloc.Data.Type = TargetObjectWriter->getRelocType(Target, Fixup,
-                                                     CrossSection);
+  Reloc.Data.Type =
+      TargetObjectWriter->getRelocType(Target, Fixup, CrossSection,
+                                       Asm.getBackend());
 
   // FIXME: Can anyone explain what this does other than adjust for the size
   // of the offset?

lib/Target/ARM/MCTargetDesc/ARMWinCOFFObjectWriter.cpp

@@ -8,9 +8,12 @@
 //===----------------------------------------------------------------------===//
 
 #include "MCTargetDesc/ARMFixupKinds.h"
+#include "llvm/MC/MCAsmBackend.h"
 #include "llvm/MC/MCFixup.h"
+#include "llvm/MC/MCFixupKindInfo.h"
 #include "llvm/MC/MCValue.h"
 #include "llvm/MC/MCWinCOFFObjectWriter.h"
+#include "llvm/ADT/Twine.h"
 #include "llvm/Support/COFF.h"
 #include "llvm/Support/Debug.h"
 
@@ -26,14 +29,16 @@ public:
   virtual ~ARMWinCOFFObjectWriter() { }
 
   unsigned getRelocType(const MCValue &Target, const MCFixup &Fixup,
-                        bool IsCrossSection) const override;
+                        bool IsCrossSection,
+                        const MCAsmBackend &MAB) const override;
 
   bool recordRelocation(const MCFixup &) const override;
 };
 
 unsigned ARMWinCOFFObjectWriter::getRelocType(const MCValue &Target,
                                               const MCFixup &Fixup,
-                                              bool IsCrossSection) const {
+                                              bool IsCrossSection,
+                                              const MCAsmBackend &MAB) const {
   assert(getMachine() == COFF::IMAGE_FILE_MACHINE_ARMNT &&
          "AArch64 support not yet implemented");
 
@@ -41,7 +46,10 @@ unsigned ARMWinCOFFObjectWriter::getRelocType(const MCValue &Target,
     Target.isAbsolute() ? MCSymbolRefExpr::VK_None : Target.getSymA()->getKind();
 
   switch (static_cast<unsigned>(Fixup.getKind())) {
-  default: llvm_unreachable("unsupported relocation type");
+  default: {
+    const MCFixupKindInfo &Info = MAB.getFixupKindInfo(Fixup.getKind());
+    report_fatal_error(Twine("unsupported relocation type: ") + Info.Name);
+  }
   case FK_Data_4:
     switch (Modifier) {
     case MCSymbolRefExpr::VK_COFF_IMGREL32:

lib/Target/X86/MCTargetDesc/X86WinCOFFObjectWriter.cpp

@@ -28,7 +28,8 @@ namespace {
     virtual ~X86WinCOFFObjectWriter();
 
     unsigned getRelocType(const MCValue &Target, const MCFixup &Fixup,
-                          bool IsCrossSection) const override;
+                          bool IsCrossSection,
+                          const MCAsmBackend &MAB) const override;
   };
 }
 
@@ -40,7 +41,8 @@ X86WinCOFFObjectWriter::~X86WinCOFFObjectWriter() {}
 
 unsigned X86WinCOFFObjectWriter::getRelocType(const MCValue &Target,
                                               const MCFixup &Fixup,
-                                              bool IsCrossSection) const {
+                                              bool IsCrossSection,
+                                              const MCAsmBackend &MAB) const {
   unsigned FixupKind = IsCrossSection ? FK_PCRel_4 : Fixup.getKind();
 
   MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ?

test/MC/ARM/Windows/invalid-relocation.s

@@ -0,0 +1,14 @@
+# RUN: not llvm-mc -triple thumbv7-windows -filetype obj -o /dev/null 2>&1 %s \
+# RUN:     | FileCheck %s
+
+	.def invalid_relocation
+		.type 32
+		.scl 2
+	.endef
+	.global invalid_relocation
+	.thumb_func
+invalid_relocation:
+	adr r0, invalid_relocation+1
+
+# CHECK: LLVM ERROR: unsupported relocation type: fixup_t2_adr_pcrel_12
+