Subzero: Support non-IRT immediate calls with -filetype=iasm.

pydir/crosstest.py

@@ -146,9 +146,11 @@ def main():
     compiler = '{bin}/{prefix}{cc}'.format(
         bin=bindir, prefix='pnacl-' if args.sandbox else '',
         cc='clang' if pure_c else 'clang++')
-    sb_native_args = (['-O0', '--pnacl-allow-native', '-arch', 'x8632']
+    sb_native_args = (['-O0', '--pnacl-allow-native', '-arch', 'x8632',
+                       '-Wn,-defsym=__Sz_AbsoluteZero=0']
                       if args.sandbox else
-                      ['-g', '-m32', '-lm', '-lpthread'])
+                      ['-g', '-m32', '-lm', '-lpthread',
+                       '-Wl,--defsym=__Sz_AbsoluteZero=0'])
     shellcmd([compiler, args.driver] + objs +
              ['-o', os.path.join(args.dir, args.output)] + sb_native_args)
 

pydir/szbuild.py

@@ -297,6 +297,7 @@ def ProcessPexe(args, pexe, exe):
             '{linklib}/libpnacl_irt_shim_dummy.a --start-group ' +
             '{linklib}/libgcc.a {linklib}/libcrt_platform.a ' +
             '--end-group {linklib}/crtend.o --undefined=_start ' +
+            '--defsym=__Sz_AbsoluteZero=0 ' +
             '-o {exe}'
             ).format(gold=gold, linklib=linklib, partial=obj_partial, exe=exe,
                      root=nacl_root),
@@ -309,7 +310,8 @@ def ProcessPexe(args, pexe, exe):
             '{root}/toolchain/linux_x86/pnacl_newlib/translator/x86-32-linux/' +
             'lib/{{unsandboxed_irt,irt_random,irt_query_list}}.o ' +
             '{root}/toolchain_build/src/subzero/build/runtime/' +
-            'szrt_native_x8632.o -lpthread -lrt'
+            'szrt_native_x8632.o -lpthread -lrt ' +
+            '-Wl,--defsym=__Sz_AbsoluteZero=0'
             ).format(ld=linker, partial=obj_partial, exe=exe, root=nacl_root),
                  echo=args.verbose)
 

src/IceFixups.cpp

@@ -46,13 +46,15 @@ IceString AssemblerFixup::symbol(const GlobalContext *Ctx) const {
   return Str.str();
 }
 
-void AssemblerFixup::emit(GlobalContext *Ctx) const {
+void AssemblerFixup::emit(GlobalContext *Ctx, RelocOffsetT BaseOffset) const {
+  if (!ALLOW_DUMP)
+    return;
   Ostream &Str = Ctx->getStrEmit();
-  // TODO(jvoung): Not yet clear how to emit a relocation against
-  // the null symbol.
-  assert(!isNullSymbol());
-  Str << symbol(Ctx);
-  RelocOffsetT Offset = offset();
+  if (isNullSymbol())
+    Str << "__Sz_AbsoluteZero";
+  else
+    Str << symbol(Ctx);
+  RelocOffsetT Offset = offset() + BaseOffset;
   if (Offset)
     Str << " + " << Offset;
 }

src/IceFixups.h

@@ -44,7 +44,7 @@ public:
 
   void set_value(const Constant *Value) { value_ = Value; }
 
-  void emit(GlobalContext *Ctx) const;
+  void emit(GlobalContext *Ctx, RelocOffsetT BaseOffset) const;
 
 private:
   intptr_t position_;

src/assembler.cpp

@@ -136,9 +136,9 @@ void Assembler::emitIASBytes(GlobalContext *Ctx) const {
       Str << "\n";
     }
     Str << "\t.long ";
-    NextFixup->emit(Ctx);
+    NextFixup->emit(Ctx, buffer_.Load<RelocOffsetT>(NextFixupLoc));
     if (fixupIsPCRel(NextFixup->kind()))
-      Str << " - (. + " << FixupSize << ")";
+      Str << " - .";
     Str << "\n";
     CurPosition = NextFixupLoc + FixupSize;
     assert(CurPosition <= EndPosition);