D116233.diff

diff --git a/clang/lib/Driver/ToolChains/Arch/ARM.cpp b/clang/lib/Driver/ToolChains/Arch/ARM.cpp
index 4013cf230026..400b7fafd6d7 100644
--- a/clang/lib/Driver/ToolChains/Arch/ARM.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/ARM.cpp
@@ -160,26 +160,44 @@ bool arm::isHardTPSupported(const llvm::Triple &Triple) {
 // Select mode for reading thread pointer (-mtp=soft/cp15).
 arm::ReadTPMode arm::getReadTPMode(const Driver &D, const ArgList &Args,
                                    const llvm::Triple &Triple, bool ForAS) {
+  // Default to Soft.
+  ReadTPMode Mode = ReadTPMode::Soft;
+
+  // -mstack-protector-guard=tls implies -mtp=cp15.
+  if (Arg *A = Args.getLastArg(options::OPT_mstack_protector_guard_EQ))
+    if (StringRef(A->getValue()) == "tls")
+      Mode = ReadTPMode::Cp15;
+
+  // -mtp= overrides previous settings.
   if (Arg *A = Args.getLastArg(options::OPT_mtp_mode_EQ)) {
-    arm::ReadTPMode ThreadPointer =
-        llvm::StringSwitch<arm::ReadTPMode>(A->getValue())
-            .Case("cp15", ReadTPMode::Cp15)
-            .Case("soft", ReadTPMode::Soft)
-            .Default(ReadTPMode::Invalid);
-    if (ThreadPointer == ReadTPMode::Cp15 && !isHardTPSupported(Triple) &&
-        !ForAS) {
-      D.Diag(diag::err_target_unsupported_tp_hard) << Triple.getArchName();
-      return ReadTPMode::Invalid;
+    ReadTPMode MTP = llvm::StringSwitch<arm::ReadTPMode>(A->getValue())
+      .Case("cp15", ReadTPMode::Cp15)
+      .Case("soft", ReadTPMode::Soft)
+      .Default(ReadTPMode::Invalid);
+
+    // Diagnose unexpected values for -mtp=.
+    if (MTP == ReadTPMode::Invalid) {
+      if (StringRef(A->getValue()).empty())
+        D.Diag(diag::err_drv_missing_arg_mtp) << A->getAsString(Args);
+      else
+        D.Diag(diag::err_drv_invalid_mtp) << A->getAsString(Args);
     }
-    if (ThreadPointer != ReadTPMode::Invalid)
-      return ThreadPointer;
-    if (StringRef(A->getValue()).empty())
-      D.Diag(diag::err_drv_missing_arg_mtp) << A->getAsString(Args);
-    else
-      D.Diag(diag::err_drv_invalid_mtp) << A->getAsString(Args);
-    return ReadTPMode::Invalid;
+
+    // Check if -mtp= is being used to override -mstack-protector-guard=.
+    if (Mode == ReadTPMode::Cp15 && MTP != Mode) {
+      D.Diag(diag::err_drv_argument_not_allowed_with) << A->getAsString(Args)
+        << "-mstack-protector-guard=tls";
+      Mode = ReadTPMode::Invalid;
+    } else
+      Mode = MTP;
+  }
+
+  // Diagnose if hardware TLS was requested but isn't supported by this triple.
+  if (Mode == ReadTPMode::Cp15 && !isHardTPSupported(Triple) && !ForAS) {
+    D.Diag(diag::err_target_unsupported_tp_hard) << Triple.getArchName();
+    Mode = ReadTPMode::Invalid;
   }
-  return ReadTPMode::Soft;
+  return Mode;
 }
 
 void arm::setArchNameInTriple(const Driver &D, const ArgList &Args,
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 2a3723975568..e75143229ad3 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -3217,22 +3217,9 @@ static void RenderSSPOptions(const Driver &D, const ToolChain &TC,
         return;
       }
       // Check whether the target subarch supports the hardware TLS register
-      if (arm::getARMSubArchVersionNumber(EffectiveTriple) < 7 &&
-          llvm::ARM::parseArch(EffectiveTriple.getArchName()) !=
-              llvm::ARM::ArchKind::ARMV6T2) {
-        D.Diag(diag::err_target_unsupported_tp_hard)
-            << EffectiveTriple.getArchName();
+      // then check whether the user asked for something other than -mtp=cp15.
+      if (arm::getReadTPMode(D, Args, EffectiveTriple, false) != arm::ReadTPMode::Cp15)
         return;
-      }
-      // Check whether the user asked for something other than -mtp=cp15
-      if (Arg *A = Args.getLastArg(options::OPT_mtp_mode_EQ)) {
-        StringRef Value = A->getValue();
-        if (Value != "cp15") {
-          D.Diag(diag::err_drv_argument_not_allowed_with)
-              << A->getAsString(Args) << "-mstack-protector-guard=tls";
-          return;
-        }
-      }
       CmdArgs.push_back("-target-feature");
       CmdArgs.push_back("+read-tp-hard");
     }