From 73ee4e1cbd643028d63200f05199a128609aba5f Mon Sep 17 00:00:00 2001
From: Nick Desaulniers <ndesaulniers@google.com>
Date: Mon, 6 Dec 2021 11:11:19 -0800
Subject: [PATCH] [clang][ARM] only check -mtp=cp15 for non-asm sources

This diagnostic is really to highlight lack of support for hard thread
pointers in post-RA instruction scheduling for non-armv6k+ targets;
something that isn't run for assembler sources.

Fixes: https://github.com/ClangBuiltLinux/linux/issues/1502
Link: https://lore.kernel.org/all/814585495.6773.1636629846970@jenkins.jenkins/

Reviewed By: ardb

Differential Revision: https://reviews.llvm.org/D114124
---
 clang/lib/Driver/ToolChains/Arch/ARM.cpp | 7 ++++---
 clang/lib/Driver/ToolChains/Arch/ARM.h   | 2 +-
 clang/test/Driver/clang-translation.c    | 4 ++++
 3 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/Arch/ARM.cpp b/clang/lib/Driver/ToolChains/Arch/ARM.cpp
index e03bed0a6de6..4013cf230026 100644
--- a/clang/lib/Driver/ToolChains/Arch/ARM.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/ARM.cpp
@@ -159,14 +159,15 @@ 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) {
+                                   const llvm::Triple &Triple, bool ForAS) {
   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)) {
+    if (ThreadPointer == ReadTPMode::Cp15 && !isHardTPSupported(Triple) &&
+        !ForAS) {
       D.Diag(diag::err_target_unsupported_tp_hard) << Triple.getArchName();
       return ReadTPMode::Invalid;
     }
@@ -488,7 +489,7 @@ void arm::getARMTargetFeatures(const Driver &D, const llvm::Triple &Triple,
     }
   }
 
-  if (getReadTPMode(D, Args, Triple) == ReadTPMode::Cp15)
+  if (getReadTPMode(D, Args, Triple, ForAS) == ReadTPMode::Cp15)
     Features.push_back("+read-tp-hard");
 
   const Arg *ArchArg = Args.getLastArg(options::OPT_march_EQ);
diff --git a/clang/lib/Driver/ToolChains/Arch/ARM.h b/clang/lib/Driver/ToolChains/Arch/ARM.h
index fc5b8c87bef9..881b63bd36b9 100644
--- a/clang/lib/Driver/ToolChains/Arch/ARM.h
+++ b/clang/lib/Driver/ToolChains/Arch/ARM.h
@@ -55,7 +55,7 @@ void setFloatABIInTriple(const Driver &D, const llvm::opt::ArgList &Args,
                          llvm::Triple &triple);
 bool isHardTPSupported(const llvm::Triple &Triple);
 ReadTPMode getReadTPMode(const Driver &D, const llvm::opt::ArgList &Args,
-                         const llvm::Triple &Triple);
+                         const llvm::Triple &Triple, bool ForAS);
 void setArchNameInTriple(const Driver &D, const llvm::opt::ArgList &Args,
                          types::ID InputType, llvm::Triple &Triple);
 
diff --git a/clang/test/Driver/clang-translation.c b/clang/test/Driver/clang-translation.c
index 32dd43b8352f..7d24d4c9d51c 100644
--- a/clang/test/Driver/clang-translation.c
+++ b/clang/test/Driver/clang-translation.c
@@ -126,6 +126,10 @@
 // RUN: FileCheck -check-prefix=ARM_THREAD_POINTER-HARD %s
 // ARM_THREAD_POINTER-HARD: "-target-feature" "+read-tp-hard"
 
+// RUN: %clang -target armv5t-linux -mtp=cp15 -x assembler -### %s 2>&1 | \
+// RUN: FileCheck -check-prefix=ARMv5_THREAD_POINTER_ASSEMBLER %s
+// ARMv5_THREAD_POINTER_ASSEMBLER-NOT: hardware TLS register is not supported for the armv5 sub-architecture
+
 // RUN: %clang -target armv6-linux -mthumb -mtp=cp15 -### -S %s 2>&1 | \
 // RUN: FileCheck -check-prefix=THUMBv6_THREAD_POINTER_UNSUPP %s
 // RUN: %clang -target thumbv6-linux -mthumb -mtp=cp15 -### -S %s 2>&1 | \
-- 
2.35.1.265.g69c8d7142f-goog