clang 3.9.0 -fno-delete-null-pointer-checks

fno_delete_null_pointer_checks.diff

diff --git a/tools/clang/include/clang/Driver/Options.td b/tools/clang/include/clang/Driver/Options.td
index d03ab04..0e03a0a 100644
--- a/tools/clang/include/clang/Driver/Options.td
+++ b/tools/clang/include/clang/Driver/Options.td
@@ -479,6 +479,12 @@ def fno_autolink : Flag <["-"], "fno-autolink">, Group<f_Group>,
   Flags<[DriverOption, CC1Option]>,
   HelpText<"Disable generation of linker directives for automatic library linking">;
 
+def fdelete_null_pointer_checks : Flag<["-"], "fdelete-null-pointer-checks">,
+    Group<f_Group>, Flags<[CC1Option]>,
+    HelpText<"Assume that programs cannot safely dereference null pointers">;
+def fno_delete_null_pointer_checks : Flag<["-"], "fno-delete-null-pointer-checks">,
+    Group<f_Group>, Flags<[CC1Option]>;
+
 def fembed_bitcode_EQ : Joined<["-"], "fembed-bitcode=">,
     Group<f_Group>, Flags<[DriverOption, CC1Option]>, MetaVarName<"<option>">,
     HelpText<"Embed LLVM bitcode (option: off, all, bitcode, marker)">;
@@ -2109,8 +2115,6 @@ defm reorder_blocks : BooleanFFlag<"reorder-blocks">, Group<clang_ignored_gcc_op
 defm eliminate_unused_debug_types : BooleanFFlag<"eliminate-unused-debug-types">, Group<clang_ignored_f_Group>;
 defm branch_count_reg : BooleanFFlag<"branch-count-reg">, Group<clang_ignored_gcc_optimization_f_Group>;
 defm default_inline : BooleanFFlag<"default-inline">, Group<clang_ignored_gcc_optimization_f_Group>;
-defm delete_null_pointer_checks : BooleanFFlag<"delete-null-pointer-checks">,
-    Group<clang_ignored_gcc_optimization_f_Group>;
 defm fat_lto_objects : BooleanFFlag<"fat-lto-objects">, Group<clang_ignored_gcc_optimization_f_Group>;
 defm float_store : BooleanFFlag<"float-store">, Group<clang_ignored_gcc_optimization_f_Group>;
 defm friend_injection : BooleanFFlag<"friend-injection">, Group<clang_ignored_f_Group>;
 diff --git a/tools/clang/include/clang/Frontend/CodeGenOptions.def b/tools/clang/include/clang/Frontend/CodeGenOptions.def
index 6a4474c..d063ed9 100644
--- a/tools/clang/include/clang/Frontend/CodeGenOptions.def
+++ b/tools/clang/include/clang/Frontend/CodeGenOptions.def
@@ -44,6 +44,7 @@ CODEGENOPT(CXXCtorDtorAliases, 1, 0) ///< Emit complete ctors/dtors as linker
                                      ///< aliases to base ctors when possible.
 CODEGENOPT(DataSections      , 1, 0) ///< Set when -fdata-sections is enabled.
 CODEGENOPT(UniqueSectionNames, 1, 1) ///< Set for -funique-section-names.
+CODEGENOPT(DeleteNullPointerChecks , 1, 1) ///< -fdelete-null-pointer-checks
 CODEGENOPT(DisableFPElim     , 1, 0) ///< Set when -fomit-frame-pointer is enabled.
 CODEGENOPT(DisableFree       , 1, 0) ///< Don't free memory.
 CODEGENOPT(DiscardValueNames , 1, 0) ///< Discard Value Names from the IR (LLVMContext flag)
diff --git a/tools/clang/lib/CodeGen/CGExprScalar.cpp b/tools/clang/lib/CodeGen/CGExprScalar.cpp
index 120dacf..3805545 100644
--- a/tools/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/tools/clang/lib/CodeGen/CGExprScalar.cpp
@@ -1329,8 +1329,9 @@ bool CodeGenFunction::ShouldNullCheckClassCastValue(const CastExpr *CE) {
     return false;
 
   if (isa<CXXThisExpr>(E->IgnoreParens())) {
-    // We always assume that 'this' is never null.
-    return false;
+    // Assume that 'this' is never null unless -fno-delete-null-pointer-checks
+    // is enabled.
+    return !CGM.getCodeGenOpts().DeleteNullPointerChecks;
   }
 
   if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(CE)) {
diff --git a/tools/clang/lib/CodeGen/CodeGenFunction.h b/tools/clang/lib/CodeGen/CodeGenFunction.h
index 45068fa..b540606 100644
--- a/tools/clang/lib/CodeGen/CodeGenFunction.h
+++ b/tools/clang/lib/CodeGen/CodeGenFunction.h
@@ -1918,7 +1918,7 @@ public:
                                         const CXXRecordDecl *Base,
                                         bool BaseIsVirtual);
 
-  static bool ShouldNullCheckClassCastValue(const CastExpr *Cast);
+  bool ShouldNullCheckClassCastValue(const CastExpr *Cast);
 
   /// GetAddressOfBaseClass - This function will add the necessary delta to the
   /// load of 'this' and returns address of the base class.
diff --git a/tools/clang/lib/Driver/Tools.cpp b/tools/clang/lib/Driver/Tools.cpp
index 31d4360..aa649de 100644
--- a/tools/clang/lib/Driver/Tools.cpp
+++ b/tools/clang/lib/Driver/Tools.cpp
@@ -5281,6 +5281,10 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
                     options::OPT_fno_assume_sane_operator_new))
     CmdArgs.push_back("-fno-assume-sane-operator-new");
 
+  if (!Args.hasFlag(options::OPT_fdelete_null_pointer_checks,
+                    options::OPT_fno_delete_null_pointer_checks))
+    CmdArgs.push_back("-fdelete-null-pointer-checks");
+
   // -fblocks=0 is default.
   if (Args.hasFlag(options::OPT_fblocks, options::OPT_fno_blocks,
                    getToolChain().IsBlocksDefault()) ||
diff --git a/tools/clang/lib/Frontend/CompilerInvocation.cpp b/tools/clang/lib/Frontend/CompilerInvocation.cpp
index c6948eb..f35f6fb 100644
--- a/tools/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/tools/clang/lib/Frontend/CompilerInvocation.cpp
@@ -544,6 +544,9 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
   Opts.DumpCoverageMapping = Args.hasArg(OPT_dump_coverage_mapping);
   Opts.AsmVerbose = Args.hasArg(OPT_masm_verbose);
   Opts.AssumeSaneOperatorNew = !Args.hasArg(OPT_fno_assume_sane_operator_new);
+  Opts.DeleteNullPointerChecks =
+      Args.hasFlag(OPT_fdelete_null_pointer_checks,
+                   OPT_fno_delete_null_pointer_checks, true);
   Opts.ObjCAutoRefCountExceptions = Args.hasArg(OPT_fobjc_arc_exceptions);
   Opts.CXAAtExit = !Args.hasArg(OPT_fno_use_cxa_atexit);
   Opts.CXXCtorDtorAliases = Args.hasArg(OPT_mconstructor_aliases);