[libc-commits] [libc] f1ce6a4 - [libc][arm] implement a basic setjmp/longjmp (#93220)
via libc-commits
libc-commits at lists.llvm.org
Thu Jun 20 08:16:53 PDT 2024
Author: Nick Desaulniers (paternity leave)
Date: 2024-06-20T08:16:48-07:00
New Revision: f1ce6a465d09f9527151f2f36c19072d2091cbaa
URL: https://github.com/llvm/llvm-project/commit/f1ce6a465d09f9527151f2f36c19072d2091cbaa
DIFF: https://github.com/llvm/llvm-project/commit/f1ce6a465d09f9527151f2f36c19072d2091cbaa.diff
LOG: [libc][arm] implement a basic setjmp/longjmp (#93220)
Note: our baremetal arm configuration compiles this as
`--target=arm-none-eabi`, so this code is built in -marm mode. It could be
smaller with `--target=armv7-none-eabi -mthumb`. The assembler is valid ARMv5,
or THUMB2, but not THUMB(1).
Added:
libc/src/setjmp/arm/CMakeLists.txt
libc/src/setjmp/arm/longjmp.cpp
libc/src/setjmp/arm/setjmp.cpp
Modified:
libc/config/baremetal/arm/entrypoints.txt
libc/config/baremetal/arm/headers.txt
libc/config/linux/arm/entrypoints.txt
libc/config/linux/arm/headers.txt
libc/include/llvm-libc-types/jmp_buf.h
libc/include/setjmp.h.def
Removed:
################################################################################
diff --git a/libc/config/baremetal/arm/entrypoints.txt b/libc/config/baremetal/arm/entrypoints.txt
index 2930d718fdb21..c2aa5258cb7e6 100644
--- a/libc/config/baremetal/arm/entrypoints.txt
+++ b/libc/config/baremetal/arm/entrypoints.txt
@@ -26,6 +26,10 @@ set(TARGET_LIBC_ENTRYPOINTS
# errno.h entrypoints
libc.src.errno.errno
+ # setjmp.h entrypoints
+ libc.src.setjmp.longjmp
+ libc.src.setjmp.setjmp
+
# string.h entrypoints
libc.src.string.bcmp
libc.src.string.bcopy
diff --git a/libc/config/baremetal/arm/headers.txt b/libc/config/baremetal/arm/headers.txt
index 3608364e45bde..28fd1ce9128d2 100644
--- a/libc/config/baremetal/arm/headers.txt
+++ b/libc/config/baremetal/arm/headers.txt
@@ -1,13 +1,14 @@
set(TARGET_PUBLIC_HEADERS
libc.include.assert
libc.include.ctype
- libc.include.fenv
libc.include.errno
+ libc.include.fenv
libc.include.float
- libc.include.stdint
libc.include.inttypes
libc.include.math
+ libc.include.setjmp
libc.include.stdfix
+ libc.include.stdint
libc.include.stdio
libc.include.stdlib
libc.include.string
diff --git a/libc/config/linux/arm/entrypoints.txt b/libc/config/linux/arm/entrypoints.txt
index d4f932416bd9f..681d3d2583fd3 100644
--- a/libc/config/linux/arm/entrypoints.txt
+++ b/libc/config/linux/arm/entrypoints.txt
@@ -20,6 +20,10 @@ set(TARGET_LIBC_ENTRYPOINTS
# errno.h entrypoints
libc.src.errno.errno
+ # setjmp.h entrypoints
+ libc.src.setjmp.longjmp
+ libc.src.setjmp.setjmp
+
# string.h entrypoints
libc.src.string.bcmp
libc.src.string.bcopy
diff --git a/libc/config/linux/arm/headers.txt b/libc/config/linux/arm/headers.txt
index 1180564fe458c..84078a947031a 100644
--- a/libc/config/linux/arm/headers.txt
+++ b/libc/config/linux/arm/headers.txt
@@ -1,19 +1,20 @@
set(TARGET_PUBLIC_HEADERS
libc.include.ctype
- libc.include.fenv
libc.include.errno
+ libc.include.fenv
libc.include.float
- libc.include.stdint
libc.include.inttypes
libc.include.math
- libc.include.stdckdint
+ libc.include.search
+ libc.include.setjmp
libc.include.stdbit
+ libc.include.stdckdint
+ libc.include.stdint
libc.include.stdlib
libc.include.string
libc.include.strings
- libc.include.search
- libc.include.wchar
libc.include.uchar
+ libc.include.wchar
# Disabled due to epoll_wait syscalls not being available on this platform.
# libc.include.sys_epoll
diff --git a/libc/include/llvm-libc-types/jmp_buf.h b/libc/include/llvm-libc-types/jmp_buf.h
index 29a1df9ad6823..8949be9fa0ab7 100644
--- a/libc/include/llvm-libc-types/jmp_buf.h
+++ b/libc/include/llvm-libc-types/jmp_buf.h
@@ -32,6 +32,9 @@ typedef struct {
#elif defined(__riscv_float_abi_single)
#error "__jmp_buf not available for your target architecture."
#endif
+#elif defined(__arm__)
+ // r4, r5, r6, r7, r8, r9, r10, r11, r12, lr
+ long opaque[10];
#else
#error "__jmp_buf not available for your target architecture."
#endif
diff --git a/libc/include/setjmp.h.def b/libc/include/setjmp.h.def
index 670bc1ac0fe24..cb083b8cd023e 100644
--- a/libc/include/setjmp.h.def
+++ b/libc/include/setjmp.h.def
@@ -10,6 +10,7 @@
#define LLVM_LIBC_SETJMP_H
#include "__llvm-libc-common.h"
+#include "llvm-libc-types/jmp_buf.h"
%%public_api()
diff --git a/libc/src/setjmp/arm/CMakeLists.txt b/libc/src/setjmp/arm/CMakeLists.txt
new file mode 100644
index 0000000000000..da97b79c9fea0
--- /dev/null
+++ b/libc/src/setjmp/arm/CMakeLists.txt
@@ -0,0 +1,19 @@
+add_entrypoint_object(
+ setjmp
+ SRCS
+ setjmp.cpp
+ HDRS
+ ../setjmp_impl.h
+ DEPENDS
+ libc.include.setjmp
+)
+
+add_entrypoint_object(
+ longjmp
+ SRCS
+ longjmp.cpp
+ HDRS
+ ../longjmp.h
+ DEPENDS
+ libc.include.setjmp
+)
diff --git a/libc/src/setjmp/arm/longjmp.cpp b/libc/src/setjmp/arm/longjmp.cpp
new file mode 100644
index 0000000000000..a088b5800fd14
--- /dev/null
+++ b/libc/src/setjmp/arm/longjmp.cpp
@@ -0,0 +1,74 @@
+
+//===-- Implementation of longjmp -----------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/setjmp/longjmp.h"
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+#if defined(__thumb__) && __ARM_ARCH_ISA_THUMB == 1
+
+[[gnu::naked, gnu::target("thumb")]]
+LLVM_LIBC_FUNCTION(void, longjmp, (__jmp_buf * buf, int val)) {
+ asm(R"(
+ # Reload r4, r5, r6, r7.
+ ldmia r0!, {r4-r7}
+
+ # Reload r8, r9. They cannot appear in register lists so load them
+ # into the lower registers, then move them into place.
+ ldmia r0!, {r2-r3}
+ mov r8, r2
+ mov r9, r3
+
+ # Reload r10, r11. They cannot appear in register lists so load them
+ # into the lower registers, then move them into place.
+ ldmia r0!, {r2-r3}
+ mov r10, r2
+ mov r11, r3
+
+ # Reload sp, lr. They cannot appear in register lists so load them
+ # into the lower registers, then move them into place.
+ ldmia r0!, {r2-r3}
+ mov sp, r2
+ mov lr, r3
+
+ # return val ?: 1;
+ movs r0, r1
+ bne .Lret_val
+ movs r0, #1
+
+ .Lret_val:
+ bx lr)");
+}
+
+#else // Thumb2 or ARM
+
+// TODO(https://github.com/llvm/llvm-project/issues/94061): fp registers
+// (d0-d16)
+// TODO(https://github.com/llvm/llvm-project/issues/94062): pac+bti
+[[gnu::naked]]
+LLVM_LIBC_FUNCTION(void, longjmp, (__jmp_buf * buf, int val)) {
+ asm(R"(
+ # While sp may appear in a register list for ARM mode, it may not for
+ # Thumb2 mode. Just load the previous value of sp into r12 then move it
+ # into sp, so that this code is portable between ARM and Thumb2.
+
+ ldm r0, {r4-r12, lr}
+ mov sp, r12
+
+ # return val ?: 1;
+ movs r0, r1
+ it eq
+ moveq r0, #1
+ bx lr)");
+}
+
+#endif
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/setjmp/arm/setjmp.cpp b/libc/src/setjmp/arm/setjmp.cpp
new file mode 100644
index 0000000000000..287e09c4a08ba
--- /dev/null
+++ b/libc/src/setjmp/arm/setjmp.cpp
@@ -0,0 +1,64 @@
+//===-- Implementation of setjmp ------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/__support/common.h"
+#include "src/setjmp/setjmp_impl.h"
+
+namespace LIBC_NAMESPACE {
+
+#if defined(__thumb__) && __ARM_ARCH_ISA_THUMB == 1
+
+[[gnu::naked, gnu::target("thumb")]]
+LLVM_LIBC_FUNCTION(int, setjmp, (__jmp_buf * buf)) {
+ asm(R"(
+ # Store r4, r5, r6, and r7 into buf.
+ stmia r0!, {r4-r7}
+
+ # Store r8, r9, r10, r11, sp, and lr into buf. Thumb(1) doesn't support
+ # the high registers > r7 in stmia, so move them into lower GPRs first.
+ # Thumb(1) also doesn't support using str with sp or lr, move them
+ # together with the rest.
+ mov r1, r8
+ mov r2, r9
+ mov r3, r10
+ stmia r0!, {r1-r3}
+
+ mov r1, r11
+ mov r2, sp
+ mov r3, lr
+ stmia r0!, {r1-r3}
+
+ # Return 0.
+ movs r0, #0
+ bx lr)");
+}
+
+#else // Thumb2 or ARM
+
+// TODO(https://github.com/llvm/llvm-project/issues/94061): fp registers
+// (d0-d16)
+// TODO(https://github.com/llvm/llvm-project/issues/94062): pac+bti
+[[gnu::naked]]
+LLVM_LIBC_FUNCTION(int, setjmp, (__jmp_buf * buf)) {
+ asm(R"(
+ # While sp may appear in a register list for ARM mode, it may not for
+ # Thumb2 mode. Just move it into r12 then stm that, so that this code
+ # is portable between ARM and Thumb2.
+ mov r12, sp
+
+ # Store r4, r5, r6, r7, r8, r9, r10, r11, sp, and lr into buf.
+ stm r0, {r4-r12, lr}
+
+ # Return zero.
+ mov r0, #0
+ bx lr)");
+}
+
+#endif
+
+} // namespace LIBC_NAMESPACE
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