[TCWG CI] Regression caused by llvm: [ARM] reject -mtp=cp15 if target subarch does not support it

[ci_notify@linaro.org]

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[TCWG CI] Regression caused by llvm: [ARM] reject -mtp=cp15 if target subarch does not support it:
commit 24772720c54500714e2d48b9109bb62d5867ad95
Author: Ard Biesheuvel <ardb@kernel.org>

    [ARM] reject -mtp=cp15 if target subarch does not support it

Results regressed to
# reset_artifacts:
-10
# build_abe binutils:
-9
# build_llvm:
-5
# build_abe qemu:
-2
# linux_n_obj:
6359
# First few build errors in logs:
# 00:01:18 clang-14: error: hardware TLS register is not supported for the arm sub-architecture
# 00:01:18 make[2]: *** [scripts/Makefile.build:410: arch/arm/kernel/iwmmxt.o] Error 1
# 00:01:21 make[1]: *** [scripts/Makefile.build:571: arch/arm/kernel] Error 2
# 00:01:24 make: *** [Makefile:1996: arch/arm] Error 2

from
# reset_artifacts:
-10
# build_abe binutils:
-9
# build_llvm:
-5
# build_abe qemu:
-2
# linux_n_obj:
7115
# linux build successful:
all
# linux boot successful:
boot

THIS IS THE END OF INTERESTING STUFF.  BELOW ARE LINKS TO BUILDS, REPRODUCTION INSTRUCTIONS, AND THE RAW COMMIT.

This commit has regressed these CI configurations:
 - tcwg_kernel/llvm-master-arm-next-defconfig

First_bad build: https://ci.linaro.org/job/tcwg_kernel-llvm-bisect-llvm-master-arm-next-defconfig/4/artifact/artifacts/build-24772720c54500714e2d48b9109bb62d5867ad95/
Last_good build: https://ci.linaro.org/job/tcwg_kernel-llvm-bisect-llvm-master-arm-next-defconfig/4/artifact/artifacts/build-22a1aa5a43cbdaf9dde014ba1f120e0f7ca1788b/
Baseline build: https://ci.linaro.org/job/tcwg_kernel-llvm-bisect-llvm-master-arm-next-defconfig/4/artifact/artifacts/build-baseline/
Even more details: https://ci.linaro.org/job/tcwg_kernel-llvm-bisect-llvm-master-arm-next-defconfig/4/artifact/artifacts/

Reproduce builds:
<cut>
mkdir investigate-llvm-24772720c54500714e2d48b9109bb62d5867ad95
cd investigate-llvm-24772720c54500714e2d48b9109bb62d5867ad95

# Fetch scripts
git clone https://git.linaro.org/toolchain/jenkins-scripts

# Fetch manifests and test.sh script
mkdir -p artifacts/manifests
curl -o artifacts/manifests/build-baseline.sh https://ci.linaro.org/job/tcwg_kernel-llvm-bisect-llvm-master-arm-next-defconfig/4/artifact/artifacts/manifests/build-baseline.sh --fail
curl -o artifacts/manifests/build-parameters.sh https://ci.linaro.org/job/tcwg_kernel-llvm-bisect-llvm-master-arm-next-defconfig/4/artifact/artifacts/manifests/build-parameters.sh --fail
curl -o artifacts/test.sh https://ci.linaro.org/job/tcwg_kernel-llvm-bisect-llvm-master-arm-next-defconfig/4/artifact/artifacts/test.sh --fail
chmod +x artifacts/test.sh

# Reproduce the baseline build (build all pre-requisites)
./jenkins-scripts/tcwg_kernel-build.sh @@ artifacts/manifests/build-baseline.sh

# Save baseline build state (which is then restored in artifacts/test.sh)
mkdir -p ./bisect
rsync -a --del --delete-excluded --exclude /bisect/ --exclude /artifacts/ --exclude /llvm/ ./ ./bisect/baseline/

cd llvm

# Reproduce first_bad build
git checkout --detach 24772720c54500714e2d48b9109bb62d5867ad95
../artifacts/test.sh

# Reproduce last_good build
git checkout --detach 22a1aa5a43cbdaf9dde014ba1f120e0f7ca1788b
../artifacts/test.sh

cd ..
</cut>

Full commit (up to 1000 lines):
<cut>
commit 24772720c54500714e2d48b9109bb62d5867ad95
Author: Ard Biesheuvel <ardb@kernel.org>
Date:   Tue Nov 9 18:26:29 2021 +0100

    [ARM] reject -mtp=cp15 if target subarch does not support it
    
    Currently, we permit -mtp=cp15 even for targets that don't implement the
    TLS register. When building for ARMv6 or earlier, this means we emit
    instructions that will UNDEF at runtime. For Thumb1, passing -mtp=cp15
    will trigger an assert in the backend.
    
    So let's add some diagnostics to ensure that -mtp=cp15 is only accepted
    for ARMv6T2 or newer.
    
    Reviewed By: nickdesaulniers
    
    Differential Revision: https://reviews.llvm.org/D113026
---
 clang/lib/Driver/ToolChains/Arch/ARM.cpp | 12 ++++++++++--
 clang/lib/Driver/ToolChains/Arch/ARM.h   |  3 ++-
 clang/test/Driver/clang-translation.c    | 18 +++++++++++++++---
 3 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/Arch/ARM.cpp b/clang/lib/Driver/ToolChains/Arch/ARM.cpp
index 05d83c91ba0e..21c091e1a0ba 100644
--- a/clang/lib/Driver/ToolChains/Arch/ARM.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/ARM.cpp
@@ -148,13 +148,21 @@ bool arm::useAAPCSForMachO(const llvm::Triple &T) {
 }
 
 // Select mode for reading thread pointer (-mtp=soft/cp15).
-arm::ReadTPMode arm::getReadTPMode(const Driver &D, const ArgList &Args) {
+arm::ReadTPMode arm::getReadTPMode(const Driver &D, const ArgList &Args,
+                                   const llvm::Triple &Triple) {
   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 &&
+        getARMSubArchVersionNumber(Triple) < 7 &&
+        llvm::ARM::parseArch(Triple.getArchName()) !=
+            llvm::ARM::ArchKind::ARMV6T2) {
+      D.Diag(diag::err_target_unsupported_tp_hard) << Triple.getArchName();
+      return ReadTPMode::Invalid;
+    }
     if (ThreadPointer != ReadTPMode::Invalid)
       return ThreadPointer;
     if (StringRef(A->getValue()).empty())
@@ -422,7 +430,7 @@ void arm::getARMTargetFeatures(const Driver &D, const llvm::Triple &Triple,
   bool KernelOrKext =
       Args.hasArg(options::OPT_mkernel, options::OPT_fapple_kext);
   arm::FloatABI ABI = arm::getARMFloatABI(D, Triple, Args);
-  arm::ReadTPMode ThreadPointer = arm::getReadTPMode(D, Args);
+  arm::ReadTPMode ThreadPointer = arm::getReadTPMode(D, Args, Triple);
   llvm::Optional<std::pair<const Arg *, StringRef>> WaCPU, WaFPU, WaHDiv,
       WaArch;
 
diff --git a/clang/lib/Driver/ToolChains/Arch/ARM.h b/clang/lib/Driver/ToolChains/Arch/ARM.h
index 0ab0d6c281f8..b6fd68fbb9c6 100644
--- a/clang/lib/Driver/ToolChains/Arch/ARM.h
+++ b/clang/lib/Driver/ToolChains/Arch/ARM.h
@@ -53,7 +53,8 @@ FloatABI getARMFloatABI(const Driver &D, const llvm::Triple &Triple,
                         const llvm::opt::ArgList &Args);
 void setFloatABIInTriple(const Driver &D, const llvm::opt::ArgList &Args,
                          llvm::Triple &triple);
-ReadTPMode getReadTPMode(const Driver &D, const llvm::opt::ArgList &Args);
+ReadTPMode getReadTPMode(const Driver &D, const llvm::opt::ArgList &Args,
+                         const llvm::Triple &Triple);
 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 9802ee3da239..230ea8e30202 100644
--- a/clang/test/Driver/clang-translation.c
+++ b/clang/test/Driver/clang-translation.c
@@ -110,15 +110,27 @@
 // ARMV5E: "-cc1"
 // ARMV5E: "-target-cpu" "arm1022e"
 
-// RUN: %clang -target arm-linux -mtp=cp15 -### -S %s -arch armv7 2>&1 | \
+// RUN: %clang -target armv7-linux -mtp=cp15 -### -S %s 2>&1 | \
 // RUN: FileCheck -check-prefix=ARMv7_THREAD_POINTER-HARD %s
 // ARMv7_THREAD_POINTER-HARD: "-target-feature" "+read-tp-hard"
 
-// RUN: %clang -target arm-linux -mtp=soft -### -S %s -arch armv7 2>&1 | \
+// RUN: %clang -target armv6t2-linux -mtp=cp15 -### -S %s 2>&1 | \
+// RUN: FileCheck -check-prefix=ARMv6T2_THREAD_POINTER-HARD %s
+// ARMv6T2_THREAD_POINTER-HARD: "-target-feature" "+read-tp-hard"
+
+// RUN: %clang -target armv5t-linux -mtp=cp15 -### -S %s 2>&1 | \
+// RUN: FileCheck -check-prefix=ARMv5_THREAD_POINTER_UNSUPP %s
+// ARMv5_THREAD_POINTER_UNSUPP: hardware TLS register is not supported for the armv5 sub-architecture
+
+// RUN: %clang -target thumbv6-linux -mtp=cp15 -### -S %s 2>&1 | \
+// RUN: FileCheck -check-prefix=ARMv6_THREAD_POINTER_UNSUPP %s
+// ARMv6_THREAD_POINTER_UNSUPP: hardware TLS register is not supported for the armv6 sub-architecture
+
+// RUN: %clang -target armv7-linux -mtp=soft -### -S %s 2>&1 | \
 // RUN: FileCheck -check-prefix=ARMv7_THREAD_POINTER_SOFT %s
 // ARMv7_THREAD_POINTER_SOFT-NOT: "-target-feature" "+read-tp-hard"
 
-// RUN: %clang -target arm-linux -### -S %s -arch armv7 2>&1 | \
+// RUN: %clang -target armv7-linux -### -S %s 2>&1 | \
 // RUN: FileCheck -check-prefix=ARMv7_THREAD_POINTER_NON %s
 // ARMv7_THREAD_POINTER_NON-NOT: "-target-feature" "+read-tp-hard"
 
</cut>