https://github.com/Zhenhang1213 created
https://github.com/llvm/llvm-project/pull/128901
This adds a new value auto to the possible values of the existing -mtp= clang
option which controls how the thread pointer is found. auto means the same as
soft if the target architecture doesn't support a hardware thread pointer at
all; otherwise it means the same as cp15.
This behavior is the default in gcc version 7.3.0 and later. The new auto
option is therefore also the default in clang, so this change aligns clang with
gcc.
>From 88a31a1679924d4307092161b6ae72d5d1df5113 Mon Sep 17 00:00:00 2001
From: Austin <zhenhangw...@huawei.com>
Date: Thu, 27 Feb 2025 00:11:56 +0800
Subject: [PATCH] [ARM] Introduce -mtp=auto and make it the default
This adds a new value auto to the possible values of the existing -mtp= clang
option which controls how the thread pointer is found. auto means the same as
soft if the target architecture doesn't support a hardware thread pointer at
all; otherwise it means the same as cp15.
This behavior is the default in gcc version 7.3.0 and later. The new auto
option is therefore also the default in clang, so this change aligns clang with
gcc.
---
clang/include/clang/Driver/Options.td | 2 +-
clang/lib/Driver/ToolChains/Arch/ARM.cpp | 6 +++++-
clang/lib/Driver/ToolChains/Arch/ARM.h | 1 +
clang/test/Driver/arm-thread-pointer.c | 6 +++++-
4 files changed, 12 insertions(+), 3 deletions(-)
diff --git a/clang/include/clang/Driver/Options.td
b/clang/include/clang/Driver/Options.td
index e521cbf678d93..2bd6076bea5d4 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -4711,7 +4711,7 @@ def mexecute_only : Flag<["-"], "mexecute-only">,
Group<m_arm_Features_Group>,
def mno_execute_only : Flag<["-"], "mno-execute-only">,
Group<m_arm_Features_Group>,
HelpText<"Allow generation of data access to code sections (ARM only)">;
let Flags = [TargetSpecific] in {
-def mtp_mode_EQ : Joined<["-"], "mtp=">, Group<m_arm_Features_Group>,
Values<"soft,cp15,tpidrurw,tpidruro,tpidrprw,el0,el1,el2,el3,tpidr_el0,tpidr_el1,tpidr_el2,tpidr_el3,tpidrro_el0">,
+def mtp_mode_EQ : Joined<["-"], "mtp=">, Group<m_arm_Features_Group>,
Values<"soft,cp15,tpidrurw,tpidruro,tpidrprw,el0,el1,el2,el3,tpidr_el0,tpidr_el1,tpidr_el2,tpidr_el3,tpidrro_el0,auto">,
HelpText<"Thread pointer access method. "
"For AArch32: 'soft' uses a function call, or 'tpidrurw',
'tpidruro' or 'tpidrprw' use the three CP15 registers. 'cp15' is an alias for
'tpidruro'. "
"For AArch64: 'tpidr_el0', 'tpidr_el1', 'tpidr_el2', 'tpidr_el3' or
'tpidrro_el0' use the five system registers. 'elN' is an alias for
'tpidr_elN'.">;
diff --git a/clang/lib/Driver/ToolChains/Arch/ARM.cpp
b/clang/lib/Driver/ToolChains/Arch/ARM.cpp
index 3aee540d501be..ec0be8f9dc587 100644
--- a/clang/lib/Driver/ToolChains/Arch/ARM.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/ARM.cpp
@@ -223,6 +223,7 @@ arm::ReadTPMode arm::getReadTPMode(const Driver &D, const
ArgList &Args,
.Case("tpidruro", ReadTPMode::TPIDRURO)
.Case("tpidrprw", ReadTPMode::TPIDRPRW)
.Case("soft", ReadTPMode::Soft)
+ .Case("auto", ReadTPMode::Auto)
.Default(ReadTPMode::Invalid);
if ((ThreadPointer == ReadTPMode::TPIDRURW ||
ThreadPointer == ReadTPMode::TPIDRURO ||
@@ -239,7 +240,7 @@ arm::ReadTPMode arm::getReadTPMode(const Driver &D, const
ArgList &Args,
D.Diag(diag::err_drv_invalid_mtp) << A->getAsString(Args);
return ReadTPMode::Invalid;
}
- return ReadTPMode::Soft;
+ return ReadTPMode::Auto;
}
void arm::setArchNameInTriple(const Driver &D, const ArgList &Args,
@@ -580,6 +581,9 @@ llvm::ARM::FPUKind arm::getARMTargetFeatures(const Driver
&D,
Features.push_back("+read-tp-tpidruro");
if (getReadTPMode(D, Args, Triple, ForAS) == ReadTPMode::TPIDRPRW)
Features.push_back("+read-tp-tpidrprw");
+ if (getReadTPMode(D, Args, Triple, ForAS) == ReadTPMode::Auto &&
+ isHardTPSupported(Triple) && !ForAS)
+ Features.push_back("+read-tp-tpidruro");
const Arg *ArchArg = Args.getLastArg(options::OPT_march_EQ);
const Arg *CPUArg = Args.getLastArg(options::OPT_mcpu_EQ);
diff --git a/clang/lib/Driver/ToolChains/Arch/ARM.h
b/clang/lib/Driver/ToolChains/Arch/ARM.h
index a23a8793a89e2..622383cf0025d 100644
--- a/clang/lib/Driver/ToolChains/Arch/ARM.h
+++ b/clang/lib/Driver/ToolChains/Arch/ARM.h
@@ -41,6 +41,7 @@ enum class ReadTPMode {
TPIDRURW,
TPIDRURO,
TPIDRPRW,
+ Auto,
};
enum class FloatABI {
diff --git a/clang/test/Driver/arm-thread-pointer.c
b/clang/test/Driver/arm-thread-pointer.c
index 5521e1865b276..985c5046f6d26 100644
--- a/clang/test/Driver/arm-thread-pointer.c
+++ b/clang/test/Driver/arm-thread-pointer.c
@@ -42,4 +42,8 @@
// 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-tpidruro"
+// ARMv7_THREAD_POINTER_NON: "-target-feature" "+read-tp-tpidruro"
+
+// 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"
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