Disable "UseOdrIndicator" ASan instrumentation mode by default.

Previously Swift enabled the "UseOdrIndicator" ASan instrumentation mode
and gave no option to disable this. This probably wasn't intentional but
happened due to the fact the
`createModuleAddressSanitizerLegacyPassPass()` function has a default
value for the `UseOdrIndicator` parameter of `true` and in Swift we
never specified this parameter explicitly.

Clang disables the "UseOdrIndicator" mode by default but allows it to be
enabled using the `-fsanitize-address-use-odr-indicator` flag.
Having "UseOdrIndicator" off by default is probably the right
default choice because it bloats the binary. So this patch changes the
Swift compiler to match Clang's behavior.

This patch disables the "UseOdrIndicator" mode by default but adds a
hidden driver and frontend flag (`-sanitize-address-use-odr-indicator`)
to enable it. The flag is hidden so that we can remove it in the future
if needed.

A side of disabling "UseOdrIndicator" is that by we will no longer use
private aliases for poisoning globals. Private aliases were introduced
to avoid crashes (google/sanitizers#398) due
to ODR violations with non-instrumented binaries. On Apple platforms the
use of two-level namespaces probably means that using private aliases
wasn't ever really necessary to avoid crashes. On platforms with a flat
linking namespace (e.g. Linux) using private aliases might matter more
but should users actually run into problems they can either:

* Fix their environment to remove the ODR, thus avoiding the crash.
* Instrument the previously non-instrumented code to avoid the crash.
* Use the new `-sanitize-address-use-odr-indicator` flag

rdar://problem/69335186

Author: danliew-apple

include/swift/AST/IRGenOptions.h

@@ -190,6 +190,9 @@ class IRGenOptions {
   /// Which sanitizer(s) have recovery instrumentation enabled.
   OptionSet<SanitizerKind> SanitizersWithRecoveryInstrumentation;
 
+  /// Whether to enable ODR indicators when building with ASan.
+  unsigned SanitizeAddressUseODRIndicator : 1;
+
   /// Path prefixes that should be rewritten in debug info.
   PathRemapper DebugPrefixMap;
 
@@ -345,6 +348,7 @@ class IRGenOptions {
         Verify(true), OptMode(OptimizationMode::NotSet),
         Sanitizers(OptionSet<SanitizerKind>()),
         SanitizersWithRecoveryInstrumentation(OptionSet<SanitizerKind>()),
+        SanitizeAddressUseODRIndicator(false),
         DebugInfoLevel(IRGenDebugInfoLevel::None),
         DebugInfoFormat(IRGenDebugInfoFormat::None),
         DisableClangModuleSkeletonCUs(false), UseJIT(false),

include/swift/Option/Options.td

@@ -1104,6 +1104,13 @@ def sanitize_recover_EQ
                "checks should be comma separated. Default behavior is to not "
                "allow error recovery.">;
 
+def sanitize_address_use_odr_indicator
+    : Flag<["-"], "sanitize-address-use-odr-indicator">,
+      Flags<[FrontendOption, NoInteractiveOption, HelpHidden]>,
+      HelpText<"When using AddressSanitizer enable ODR indicator globals to "
+               "avoid false ODR violation reports in partially sanitized "
+               "programs at the cost of an increase in binary size">;
+
 def sanitize_coverage_EQ : CommaJoined<["-"], "sanitize-coverage=">,
   Flags<[FrontendOption, NoInteractiveOption]>,
   MetaVarName<"<type>">,

lib/Driver/ToolChains.cpp

@@ -246,6 +246,8 @@ void ToolChain::addCommonFrontendArgs(const OutputInfo &OI,
                        options::OPT_no_warnings_as_errors);
   inputArgs.AddLastArg(arguments, options::OPT_sanitize_EQ);
   inputArgs.AddLastArg(arguments, options::OPT_sanitize_recover_EQ);
+  inputArgs.AddLastArg(arguments,
+                       options::OPT_sanitize_address_use_odr_indicator);
   inputArgs.AddLastArg(arguments, options::OPT_sanitize_coverage_EQ);
   inputArgs.AddLastArg(arguments, options::OPT_static);
   inputArgs.AddLastArg(arguments, options::OPT_swift_version);

lib/Frontend/CompilerInvocation.cpp

@@ -1228,6 +1228,10 @@ static bool ParseSILArgs(SILOptions &Opts, ArgList &Args,
                                        /*emitWarnings=*/true);
   }
 
+  if (Args.getLastArg(options::OPT_sanitize_address_use_odr_indicator)) {
+    IRGenOpts.SanitizeAddressUseODRIndicator = true;
+  }
+
   if (auto A = Args.getLastArg(OPT_enable_verify_exclusivity,
                                OPT_disable_verify_exclusivity)) {
     Opts.VerifyExclusivity

lib/IRGen/IRGen.cpp

@@ -134,9 +134,11 @@ static void addAddressSanitizerPasses(const PassManagerBuilder &Builder,
   auto recover =
       bool(BuilderWrapper.IRGOpts.SanitizersWithRecoveryInstrumentation &
            SanitizerKind::Address);
+  auto useODRIndicator = BuilderWrapper.IRGOpts.SanitizeAddressUseODRIndicator;
   PM.add(createAddressSanitizerFunctionPass(/*CompileKernel=*/false, recover));
-  PM.add(createModuleAddressSanitizerLegacyPassPass(/*CompileKernel=*/false,
-                                                    recover));
+  PM.add(createModuleAddressSanitizerLegacyPassPass(
+      /*CompileKernel=*/false, recover, /*UseGlobalsGC=*/true,
+      useODRIndicator));
 }
 
 static void addThreadSanitizerPass(const PassManagerBuilder &Builder,

test/Driver/sanitize_address_use_odr_indicator.swift

@@ -0,0 +1,5 @@
+// RUN: %swiftc_driver -driver-print-jobs -sanitize=address -sanitize-address-use-odr-indicator %s 2>&1 | %FileCheck %s
+
+// CHECK: swift
+// CHECK-DAG: -sanitize=address
+// CHECK-DAG: -sanitize-address-use-odr-indicator

test/IRGen/address_sanitizer_use_odr_indicator.swift

@@ -0,0 +1,18 @@
+// REQUIRES: asan_runtime
+
+// Default instrumentation that does not use ODR indicators
+// and private aliases.
+// RUN: %target-swift-frontend -emit-ir -sanitize=address %s | %FileCheck %s
+// CHECK: @"[[MANGLED_GLOBAL:.+aGlobal.+]]" =
+// CHECK-NOT: __odr_asan_gen_[[MANGLED_GLOBAL]]
+// CHECK-NOT: @{{.+}} = private alias {{.*}}@"[[MANGLED_GLOBAL]]"
+
+// Instrumentation with ODR indicators (implies private aliases)
+// RUN: %target-swift-frontend -emit-ir -sanitize=address \
+// RUN:   -sanitize-address-use-odr-indicator %s | \
+// RUN:   %FileCheck -check-prefix=CHECK-ODR %s
+// CHECK-ODR: @"[[MANGLED_GLOBAL:.+aGlobal.+]]" =
+// CHECK-ODR: __odr_asan_gen_[[MANGLED_GLOBAL]]
+// CHECK-ODR: @{{.+}} = private alias {{.*}}@"[[MANGLED_GLOBAL]]"
+
+let aGlobal:Int = 128;

test/Sanitizers/asan.swift

@@ -1,6 +1,14 @@
 // RUN: %target-swiftc_driver %s -target %sanitizers-target-triple -g -sanitize=address -o %t_asan-binary
 // RUN: %target-codesign %t_asan-binary
 // RUN: env %env-ASAN_OPTIONS=abort_on_error=0 not %target-run %t_asan-binary 2>&1 | %FileCheck %s
+
+// ODR Indicator variant
+// RUN: %target-swiftc_driver %s -target %sanitizers-target-triple -g -sanitize=address \
+// RUN:   -sanitize-address-use-odr-indicator -o %t_asan-binary-odr-indicator
+// RUN: %target-codesign %t_asan-binary-odr-indicator
+// RUN: env %env-ASAN_OPTIONS=abort_on_error=0 not %target-run \
+// RUN:   %t_asan-binary-odr-indicator 2>&1 | %FileCheck %s
+
 // REQUIRES: executable_test
 // REQUIRES: asan_runtime