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.

llvm-svn: 226779

3 files changed, 18 insertions, 7 deletions

diff --git a/llvm/lib/MC/WinCOFFObjectWriter.cpp b/llvm/lib/MC/WinCOFFObjectWriter.cpp
index d8729bdbc4b..bd750af5de4 100644
--- a/llvm/lib/MC/WinCOFFObjectWriter.cpp
+++ b/llvm/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?
diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMWinCOFFObjectWriter.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMWinCOFFObjectWriter.cpp
index d31f1f41c69..2ee0e511b53 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMWinCOFFObjectWriter.cpp
+++ b/llvm/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:
diff --git a/llvm/lib/Target/X86/MCTargetDesc/X86WinCOFFObjectWriter.cpp b/llvm/lib/Target/X86/MCTargetDesc/X86WinCOFFObjectWriter.cpp
index 40af822953c..e1df5c2d3c7 100644
--- a/llvm/lib/Target/X86/MCTargetDesc/X86WinCOFFObjectWriter.cpp
+++ b/llvm/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() ?