[clang] Fix mtp (PR #130022)
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cfe-commits at lists.llvm.org
Thu Mar 6 01:10:57 PST 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang
Author: Austin (Zhenhang1213)
<details>
<summary>Changes</summary>
---
Full diff: https://github.com/llvm/llvm-project/pull/130022.diff
5 Files Affected:
- (modified) clang/docs/ReleaseNotes.rst (+4)
- (modified) clang/include/clang/Driver/Options.td (+1-1)
- (modified) clang/lib/Driver/ToolChains/Arch/ARM.cpp (+18-8)
- (modified) clang/lib/Driver/ToolChains/Arch/ARM.h (+1)
- (modified) clang/test/Driver/arm-thread-pointer.c (+21-1)
``````````diff
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 7873c2048e53c..99ba3b0a848c5 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -124,6 +124,10 @@ Deprecated Compiler Flags
Modified Compiler Flags
-----------------------
+- The ARM AArch32 ``-mtp`` option accepts and defaults to ``auto``, a value of ``auto`` uses the best available method of providing the frame pointer supported by the hardware. This matches
+ the behavior of ``-mtp`` in gcc. This changes the default behavior for ARM targets that provide the ``TPIDRURO`` register as this will be used instead of a call to the ``__aeabi_read_tp``.
+ Programs that use ``__aeabi_read_tp`` but do not use the ``TPIDRURO`` register must use ``-mtp=soft``. Fixes #123864
+
Removed Compiler Flags
-------------------------
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 75b1c51445942..cce0a673f4b09 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -4729,7 +4729,7 @@ 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..b7d5b3a9a882a 100644
--- a/clang/lib/Driver/ToolChains/Arch/ARM.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/ARM.cpp
@@ -208,14 +208,22 @@ bool arm::useAAPCSForMachO(const llvm::Triple &T) {
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 ||
- (Ver >= 7 && AK != llvm::ARM::ArchKind::ARMV8MBaseline);
+ return Triple.isARM() || (Ver >= 7 && AK != llvm::ARM::ArchKind::ARMV8MBaseline);
}
+
+// We follow GCC mtp=auto when arch is arm_arch6k and support thumb2
+bool arm::isHardTPAndThumb2(const llvm::Triple &Triple) {
+ llvm::ARM::ArchKind AK = llvm::ARM::parseArch(Triple.getArchName());
+ return Triple.isARM() && AK >= llvm::ARM::ArchKind::ARMV6K && AK != llvm::ARM::ArchKind::ARMV8MBaseline;
+}
+
+
// 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) {
- if (Arg *A = Args.getLastArg(options::OPT_mtp_mode_EQ)) {
+ Arg *A = Args.getLastArg(options::OPT_mtp_mode_EQ);
+ if (A && A->getValue() != StringRef("auto")) {
arm::ReadTPMode ThreadPointer =
llvm::StringSwitch<arm::ReadTPMode>(A->getValue())
.Case("cp15", ReadTPMode::TPIDRURO)
@@ -239,7 +247,7 @@ 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 (isHardTPAndThumb2(Triple) ? ReadTPMode::TPIDRURO : ReadTPMode::Soft);
}
void arm::setArchNameInTriple(const Driver &D, const ArgList &Args,
@@ -574,12 +582,14 @@ llvm::ARM::FPUKind arm::getARMTargetFeatures(const Driver &D,
A->ignoreTargetSpecific();
}
- if (getReadTPMode(D, Args, Triple, ForAS) == ReadTPMode::TPIDRURW)
+ arm::ReadTPMode TPMode = getReadTPMode(D, Args, Triple, ForAS);
+
+ if (TPMode == ReadTPMode::TPIDRURW)
Features.push_back("+read-tp-tpidrurw");
- if (getReadTPMode(D, Args, Triple, ForAS) == ReadTPMode::TPIDRURO)
- Features.push_back("+read-tp-tpidruro");
- if (getReadTPMode(D, Args, Triple, ForAS) == ReadTPMode::TPIDRPRW)
+ else if (TPMode == ReadTPMode::TPIDRPRW)
Features.push_back("+read-tp-tpidrprw");
+ else if (TPMode == ReadTPMode::TPIDRURO)
+ 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..0641580900fd1 100644
--- a/clang/lib/Driver/ToolChains/Arch/ARM.h
+++ b/clang/lib/Driver/ToolChains/Arch/ARM.h
@@ -57,6 +57,7 @@ FloatABI getARMFloatABI(const Driver &D, const llvm::Triple &Triple,
void setFloatABIInTriple(const Driver &D, const llvm::opt::ArgList &Args,
llvm::Triple &triple);
bool isHardTPSupported(const llvm::Triple &Triple);
+bool isHardTPAndThumb2(const llvm::Triple &Triple);
ReadTPMode getReadTPMode(const Driver &D, const llvm::opt::ArgList &Args,
const llvm::Triple &Triple, bool ForAS);
void setArchNameInTriple(const Driver &D, const llvm::opt::ArgList &Args,
diff --git a/clang/test/Driver/arm-thread-pointer.c b/clang/test/Driver/arm-thread-pointer.c
index 5521e1865b276..b487a8d83fe34 100644
--- a/clang/test/Driver/arm-thread-pointer.c
+++ b/clang/test/Driver/arm-thread-pointer.c
@@ -42,4 +42,24 @@
// 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"
+
+// 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: %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"
``````````
</details>
https://github.com/llvm/llvm-project/pull/130022
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