[clang] [ARM] Using cp15 while mtp =auto and arch is arm_arch6k and support thumb2 (PR #130027)
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Thu Mar 6 17:57:42 PST 2025
https://github.com/Zhenhang1213 updated https://github.com/llvm/llvm-project/pull/130027
>From ae03b5c6bd5bf69b9fbbcaa31ca8da487648bb0f Mon Sep 17 00:00:00 2001
From: Austin <zhenhangwang at huawei.com>
Date: Thu, 6 Mar 2025 17:25:55 +0800
Subject: [PATCH] [ARM] Using cp15 while mtp =auto and arch is arm_arch6k and
support thumb2
We follow GCC mtp=auto when arch is arm_arch6k and support thumb2
Reference: https://reviews.llvm.org/D114116
---
clang/lib/Driver/ToolChains/Arch/ARM.cpp | 24 ++++++++++++--
clang/test/Driver/arm-thread-pointer.c | 41 +++++++++++++++++-------
2 files changed, 51 insertions(+), 14 deletions(-)
diff --git a/clang/lib/Driver/ToolChains/Arch/ARM.cpp b/clang/lib/Driver/ToolChains/Arch/ARM.cpp
index 51454de1b9dcc..46731a9d12bc8 100644
--- a/clang/lib/Driver/ToolChains/Arch/ARM.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/ARM.cpp
@@ -202,13 +202,25 @@ bool arm::useAAPCSForMachO(const llvm::Triple &T) {
T.getOS() == llvm::Triple::UnknownOS || isARMMProfile(T);
}
-// We follow GCC and support when the backend has support for the MRC/MCR
+// Check whether the architecture backend has support for the MRC/MCR
// instructions that are used to set the hard thread pointer ("CP15 C13
// Thread id").
+// This is not identical to ability to use the instruction, as the ARMV6K
+// variants can only use it in Arm mode since they don't support Thumb2
+// encoding.
bool arm::isHardTPSupported(const llvm::Triple &Triple) {
int Ver = getARMSubArchVersionNumber(Triple);
llvm::ARM::ArchKind AK = llvm::ARM::parseArch(Triple.getArchName());
- return Triple.isARM() || AK == llvm::ARM::ArchKind::ARMV6T2 ||
+ return AK == llvm::ARM::ArchKind::ARMV6K ||
+ AK == llvm::ARM::ArchKind::ARMV6KZ ||
+ (Ver >= 7 && !isARMMProfile(Triple));
+}
+
+// Checks whether the architecture is capable of supporting the Thumb2 encoding
+static bool supportsThumb2Encoding(const llvm::Triple &Triple) {
+ int Ver = arm::getARMSubArchVersionNumber(Triple);
+ llvm::ARM::ArchKind AK = llvm::ARM::parseArch(Triple.getArchName());
+ return AK == llvm::ARM::ArchKind::ARMV6T2 ||
(Ver >= 7 && AK != llvm::ARM::ArchKind::ARMV8MBaseline);
}
@@ -240,7 +252,13 @@ arm::ReadTPMode arm::getReadTPMode(const Driver &D, const ArgList &Args,
D.Diag(diag::err_drv_invalid_mtp) << A->getAsString(Args);
return ReadTPMode::Invalid;
}
- return (isHardTPSupported(Triple) ? ReadTPMode::TPIDRURO : ReadTPMode::Soft);
+ // In auto mode we enable HW mode only if both the hardware supports it and
+ // the thumb2 encoding. For example ARMV6T2 supports thumb2, but not hardware.
+ // ARMV6K has HW suport, but not thumb2. Otherwise we could enable it for ARMV6K
+ // in thumb mode.
+ bool autoUseHWTPMode =
+ isHardTPSupported(Triple) && supportsThumb2Encoding(Triple);
+ return autoUseHWTPMode ? ReadTPMode::TPIDRURO : ReadTPMode::Soft;
}
void arm::setArchNameInTriple(const Driver &D, const ArgList &Args,
diff --git a/clang/test/Driver/arm-thread-pointer.c b/clang/test/Driver/arm-thread-pointer.c
index 985c5046f6d26..f15cc5628a142 100644
--- a/clang/test/Driver/arm-thread-pointer.c
+++ b/clang/test/Driver/arm-thread-pointer.c
@@ -14,21 +14,17 @@
// RUN: FileCheck -check-prefix=ARMv7_THREAD_POINTER-TPIDRPRW %s
// ARMv7_THREAD_POINTER-TPIDRPRW: "-target-feature" "+read-tp-tpidrprw"
-// RUN: %clang --target=armv6t2-linux -mtp=cp15 -### -S %s 2>&1 | \
-// RUN: FileCheck -check-prefix=ARM_THREAD_POINTER-HARD %s
-// RUN: %clang --target=thumbv6t2-linux -mtp=cp15 -### -S %s 2>&1 | \
-// RUN: FileCheck -check-prefix=ARM_THREAD_POINTER-HARD %s
// RUN: %clang --target=armv6k-linux -mtp=cp15 -### -S %s 2>&1 | \
// RUN: FileCheck -check-prefix=ARM_THREAD_POINTER-HARD %s
-// RUN: %clang --target=armv6-linux -mtp=cp15 -### -S %s 2>&1 | \
-// RUN: FileCheck -check-prefix=ARM_THREAD_POINTER-HARD %s
-// RUN: %clang --target=armv5t-linux -mtp=cp15 -### -S %s 2>&1 | \
-// RUN: FileCheck -check-prefix=ARM_THREAD_POINTER-HARD %s
// ARM_THREAD_POINTER-HARD: "-target-feature" "+read-tp-tpidruro"
-// 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: not %clang --target=armv6t2-linux -mtp=cp15 -### -S %s 2>&1 | \
+// RUN: FileCheck -check-prefix=ARMv6t2_THREAD_POINTER_UNSUPP %s
+// ARMv6t2_THREAD_POINTER_UNSUPP: hardware TLS register is not supported for the armv6t2 sub-architecture
+
+// RUN: not %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: not %clang --target=armv6-linux -mthumb -mtp=cp15 -### -S %s 2>&1 | \
// RUN: FileCheck -check-prefix=THUMBv6_THREAD_POINTER_UNSUPP %s
@@ -47,3 +43,26 @@
// RUN: %clang --target=armv7-linux -mtp=auto -### -S %s 2>&1 | \
// RUN: FileCheck -check-prefix=ARMv7_THREAD_POINTER_Auto %s
// ARMv7_THREAD_POINTER_Auto: "-target-feature" "+read-tp-tpidruro"
+
+// RUN: %clang --target=armv5t-linux -mtp=auto -### -S %s 2>&1 | \
+// RUN: FileCheck -check-prefix=ARMv5t_THREAD_POINTER_Auto %s
+// ARMv5t_THREAD_POINTER_Auto-NOT: "-target-feature" "+read-tp-tpidruro"
+
+// RUN: %clang --target=armv6k-linux -mtp=auto -### -S %s 2>&1 | \
+// RUN: FileCheck -check-prefix=ARMv6k_THREAD_POINTER_Auto %s
+// ARMv6k_THREAD_POINTER_Auto: "-target-feature" "+read-tp-tpidruro"
+
+// RUN: not %clang --target=armv6-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=armv6-linux -mtp=auto -### -S %s 2>&1 | \
+// RUN: FileCheck -check-prefix=ARMv6_THREAD_POINTER_Auto %s
+// ARMv6_THREAD_POINTER_Auto-NOT: "-target-feature" "+read-tp-tpidruro"
+
+// RUN: %clang --target=armv6kz-linux -mtp=auto -### -S %s 2>&1 | \
+// RUN: FileCheck -check-prefix=ARMv6kz_THREAD_POINTER_Auto %s
+// ARMv6kz_THREAD_POINTER_Auto: "-target-feature" "+read-tp-tpidruro"
+// RUN: %clang --target=armv6kz-linux -mtp=cp15 -### -S %s 2>&1 | \
+// RUN: FileCheck -check-prefix=ARMv6kz_THREAD_POINTER_Cp15 %s
+// ARMv6kz_THREAD_POINTER_Cp15: "-target-feature" "+read-tp-tpidruro"
\ No newline at end of file
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