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[libc] Add support for setjmp and longjmp in riscv
This patch implements setjmp and longjmp in riscv using inline asm. The following changes were required: * Omit frame pointer: otherwise gcc won't allow us to use s0 * Use __attribute__((naked)): otherwise both gcc and clang will generate function prologue and epilogue in both functions. This doesn't happen in x86_64, so we guard it to only riscv Furthermore, using __attribute__((naked)) causes two problems: we can't use `return 0` (both gcc and clang) and the function arguments in the function body (clang only), so we had to use a0 and a1 directly. Reviewed By: sivachandra Differential Revision: https://reviews.llvm.org/D145584
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-28
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11 files changed

+197
-28
lines changed

‎clang/docs/tools/clang-formatted-files.txt‎

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@@ -2594,6 +2594,7 @@ libc/include/llvm-libc-types/fexcept_t.h
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libc/include/llvm-libc-types/FILE.h
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libc/include/llvm-libc-types/float_t.h
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libc/include/llvm-libc-types/imaxdiv_t.h
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libc/include/llvm-libc-types/jmp_buf.h
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libc/include/llvm-libc-types/ldiv_t.h
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libc/include/llvm-libc-types/lldiv_t.h
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libc/include/llvm-libc-types/mode_t.h

‎libc/config/linux/riscv64/entrypoints.txt‎

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@@ -371,6 +371,10 @@ if(LLVM_LIBC_FULL_BUILD)
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# sched.h entrypoints
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libc.src.sched.__sched_getcpucount
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# setjmp.h entrypoints
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libc.src.setjmp.longjmp
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libc.src.setjmp.setjmp
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# stdio.h entrypoints
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libc.src.stdio.clearerr
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libc.src.stdio.clearerr_unlocked

‎libc/config/linux/riscv64/headers.txt‎

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@@ -10,6 +10,7 @@ set(TARGET_PUBLIC_HEADERS
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libc.include.sched
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libc.include.signal
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libc.include.spawn
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libc.include.setjmp
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libc.include.stdio
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libc.include.stdlib
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libc.include.string

‎libc/include/llvm-libc-types/jmp_buf.h‎

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@@ -19,6 +19,19 @@ typedef struct {
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__UINT64_TYPE__ r15;
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__UINTPTR_TYPE__ rsp;
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__UINTPTR_TYPE__ rip;
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#elif defined(__riscv)
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/* Program counter. */
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long int __pc;
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/* Callee-saved registers. */
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long int __regs[12];
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/* Stack pointer. */
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long int __sp;
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/* Callee-saved floating point registers. */
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#if __riscv_float_abi_double
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double __fpregs[12];
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#elif defined(__riscv_float_abi_single)
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#error "__jmp_buf not available for your target architecture."
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#endif
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#else
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#error "__jmp_buf not available for your target architecture."
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#endif

‎libc/src/setjmp/CMakeLists.txt‎

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@@ -1,24 +1,17 @@
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if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/${LIBC_TARGET_ARCHITECTURE})
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add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/${LIBC_TARGET_ARCHITECTURE})
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endif()
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add_entrypoint_object(
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setjmp
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SRCS
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setjmp.cpp
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HDRS
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setjmp_impl.h
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COMPILE_OPTIONS
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-O3 # We do not want any local variables in setjmp
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-fno-omit-frame-pointer # The implementation assumes frame pointer on to the stack
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ALIAS
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DEPENDS
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libc.include.setjmp
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.${LIBC_TARGET_ARCHITECTURE}.setjmp
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)
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add_entrypoint_object(
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longjmp
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SRCS
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longjmp.cpp
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HDRS
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longjmp.h
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COMPILE_OPTIONS
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-O3 # We do not want any local variables in longjmp
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ALIAS
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DEPENDS
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libc.include.setjmp
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.${LIBC_TARGET_ARCHITECTURE}.longjmp
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)

‎libc/src/setjmp/riscv64/CMakeLists.txt‎

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@@ -0,0 +1,25 @@
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add_entrypoint_object(
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setjmp
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SRCS
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setjmp.cpp
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HDRS
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../setjmp_impl.h
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DEPENDS
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libc.include.setjmp
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COMPILE_OPTIONS
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-O3
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-fomit-frame-pointer
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)
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add_entrypoint_object(
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longjmp
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SRCS
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longjmp.cpp
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HDRS
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../longjmp.h
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DEPENDS
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libc.include.setjmp
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COMPILE_OPTIONS
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-O3
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-fomit-frame-pointer
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)

‎libc/src/setjmp/riscv64/longjmp.cpp‎

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//===-- Implementation of longjmp -----------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "src/setjmp/longjmp.h"
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#include "src/__support/common.h"
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#include "src/__support/macros/properties/architectures.h"
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#include <setjmp.h>
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#if !defined(LIBC_TARGET_ARCH_IS_RISCV64)
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#error "Invalid file include"
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#endif
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namespace __llvm_libc {
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LLVM_LIBC_FUNCTION(void, longjmp, (__jmp_buf * buf, int val)) {
22+
LIBC_INLINE_ASM("ld ra, %0\n\t" : : "m"(buf->__pc) :);
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LIBC_INLINE_ASM("ld s0, %0\n\t" : : "m"(buf->__regs[0]) :);
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LIBC_INLINE_ASM("ld s1, %0\n\t" : : "m"(buf->__regs[1]) :);
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LIBC_INLINE_ASM("ld s2, %0\n\t" : : "m"(buf->__regs[2]) :);
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LIBC_INLINE_ASM("ld s3, %0\n\t" : : "m"(buf->__regs[3]) :);
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LIBC_INLINE_ASM("ld s4, %0\n\t" : : "m"(buf->__regs[4]) :);
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LIBC_INLINE_ASM("ld s5, %0\n\t" : : "m"(buf->__regs[5]) :);
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LIBC_INLINE_ASM("ld s6, %0\n\t" : : "m"(buf->__regs[6]) :);
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LIBC_INLINE_ASM("ld s7, %0\n\t" : : "m"(buf->__regs[7]) :);
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LIBC_INLINE_ASM("ld s8, %0\n\t" : : "m"(buf->__regs[8]) :);
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LIBC_INLINE_ASM("ld s9, %0\n\t" : : "m"(buf->__regs[9]) :);
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LIBC_INLINE_ASM("ld s10, %0\n\t" : : "m"(buf->__regs[10]) :);
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LIBC_INLINE_ASM("ld s11, %0\n\t" : : "m"(buf->__regs[11]) :);
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LIBC_INLINE_ASM("ld sp, %0\n\t" : : "m"(buf->__sp) :);
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37+
#if __riscv_float_abi_double
38+
LIBC_INLINE_ASM("fld fs0, %0\n\t" : : "m"(buf->__fpregs[0]) :);
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LIBC_INLINE_ASM("fld fs1, %0\n\t" : : "m"(buf->__fpregs[1]) :);
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LIBC_INLINE_ASM("fld fs2, %0\n\t" : : "m"(buf->__fpregs[2]) :);
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LIBC_INLINE_ASM("fld fs3, %0\n\t" : : "m"(buf->__fpregs[3]) :);
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LIBC_INLINE_ASM("fld fs4, %0\n\t" : : "m"(buf->__fpregs[4]) :);
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LIBC_INLINE_ASM("fld fs5, %0\n\t" : : "m"(buf->__fpregs[5]) :);
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LIBC_INLINE_ASM("fld fs6, %0\n\t" : : "m"(buf->__fpregs[6]) :);
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LIBC_INLINE_ASM("fld fs7, %0\n\t" : : "m"(buf->__fpregs[7]) :);
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LIBC_INLINE_ASM("fld fs8, %0\n\t" : : "m"(buf->__fpregs[8]) :);
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LIBC_INLINE_ASM("fld fs9, %0\n\t" : : "m"(buf->__fpregs[9]) :);
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LIBC_INLINE_ASM("fld fs10, %0\n\t" : : "m"(buf->__fpregs[10]) :);
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LIBC_INLINE_ASM("fld fs11, %0\n\t" : : "m"(buf->__fpregs[11]) :);
50+
#elif defined(__riscv_float_abi_single)
51+
#error "longjmp implementation not available for the target architecture."
52+
#endif
53+
54+
val = val == 0 ? 1 : val;
55+
LIBC_INLINE_ASM("add a0, %0, zero\n\t" : : "r"(val) :);
56+
}
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58+
} // namespace __llvm_libc

‎libc/src/setjmp/riscv64/setjmp.cpp‎

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//===-- Implementation of setjmp ------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
5+
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
7+
//===----------------------------------------------------------------------===//
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9+
#include "src/__support/common.h"
10+
#include "src/setjmp/setjmp_impl.h"
11+
12+
#include <setjmp.h>
13+
14+
#if !defined(LIBC_TARGET_ARCH_IS_RISCV64)
15+
#error "Invalid file include"
16+
#endif
17+
18+
namespace __llvm_libc {
19+
20+
LLVM_LIBC_FUNCTION(int, setjmp, (__jmp_buf * buf)) {
21+
LIBC_INLINE_ASM("sd ra, %0\n\t" : : "m"(buf->__pc) :);
22+
LIBC_INLINE_ASM("sd s0, %0\n\t" : : "m"(buf->__regs[0]) :);
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LIBC_INLINE_ASM("sd s1, %0\n\t" : : "m"(buf->__regs[1]) :);
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LIBC_INLINE_ASM("sd s2, %0\n\t" : : "m"(buf->__regs[2]) :);
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LIBC_INLINE_ASM("sd s3, %0\n\t" : : "m"(buf->__regs[3]) :);
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LIBC_INLINE_ASM("sd s4, %0\n\t" : : "m"(buf->__regs[4]) :);
27+
LIBC_INLINE_ASM("sd s5, %0\n\t" : : "m"(buf->__regs[5]) :);
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LIBC_INLINE_ASM("sd s6, %0\n\t" : : "m"(buf->__regs[6]) :);
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LIBC_INLINE_ASM("sd s7, %0\n\t" : : "m"(buf->__regs[7]) :);
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LIBC_INLINE_ASM("sd s8, %0\n\t" : : "m"(buf->__regs[8]) :);
31+
LIBC_INLINE_ASM("sd s9, %0\n\t" : : "m"(buf->__regs[9]) :);
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LIBC_INLINE_ASM("sd s10, %0\n\t" : : "m"(buf->__regs[10]) :);
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LIBC_INLINE_ASM("sd s11, %0\n\t" : : "m"(buf->__regs[11]) :);
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LIBC_INLINE_ASM("sd sp, %0\n\t" : : "m"(buf->__sp) :);
35+
36+
#if __riscv_float_abi_double
37+
LIBC_INLINE_ASM("fsd fs0, %0\n\t" : : "m"(buf->__fpregs[0]) :);
38+
LIBC_INLINE_ASM("fsd fs1, %0\n\t" : : "m"(buf->__fpregs[1]) :);
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LIBC_INLINE_ASM("fsd fs2, %0\n\t" : : "m"(buf->__fpregs[2]) :);
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LIBC_INLINE_ASM("fsd fs3, %0\n\t" : : "m"(buf->__fpregs[3]) :);
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LIBC_INLINE_ASM("fsd fs4, %0\n\t" : : "m"(buf->__fpregs[4]) :);
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LIBC_INLINE_ASM("fsd fs5, %0\n\t" : : "m"(buf->__fpregs[5]) :);
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LIBC_INLINE_ASM("fsd fs6, %0\n\t" : : "m"(buf->__fpregs[6]) :);
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LIBC_INLINE_ASM("fsd fs7, %0\n\t" : : "m"(buf->__fpregs[7]) :);
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LIBC_INLINE_ASM("fsd fs8, %0\n\t" : : "m"(buf->__fpregs[8]) :);
46+
LIBC_INLINE_ASM("fsd fs9, %0\n\t" : : "m"(buf->__fpregs[9]) :);
47+
LIBC_INLINE_ASM("fsd fs10, %0\n\t" : : "m"(buf->__fpregs[10]) :);
48+
LIBC_INLINE_ASM("fsd fs11, %0\n\t" : : "m"(buf->__fpregs[11]) :);
49+
#elif defined(__riscv_float_abi_single)
50+
#error "setjmp implementation not available for the target architecture."
51+
#endif
52+
53+
return 0;
54+
}
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56+
} // namespace __llvm_libc

‎libc/src/setjmp/x86_64/CMakeLists.txt‎

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@@ -0,0 +1,25 @@
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add_entrypoint_object(
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setjmp
3+
SRCS
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setjmp.cpp
5+
HDRS
6+
../setjmp_impl.h
7+
DEPENDS
8+
libc.include.setjmp
9+
COMPILE_OPTIONS
10+
-O3
11+
-fno-omit-frame-pointer
12+
)
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14+
add_entrypoint_object(
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longjmp
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SRCS
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longjmp.cpp
18+
HDRS
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../longjmp.h
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DEPENDS
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libc.include.setjmp
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COMPILE_OPTIONS
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-O3
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-fno-omit-frame-pointer
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)

‎libc/src/setjmp/longjmp.cpp‎ renamed to ‎libc/src/setjmp/x86_64/longjmp.cpp‎

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@@ -8,14 +8,14 @@
88

99
#include "src/setjmp/longjmp.h"
1010
#include "src/__support/common.h"
11-
#include "src/__support/macros/properties/architectures.h"
1211

13-
#include <setjmp.h>
12+
#if !defined(LIBC_TARGET_ARCH_IS_X86_64)
13+
#error "Invalid file include"
14+
#endif
1415

1516
namespace __llvm_libc {
1617

1718
LLVM_LIBC_FUNCTION(void, longjmp, (__jmp_buf * buf, int val)) {
18-
#ifdef LIBC_TARGET_ARCH_IS_X86_64
1919
register __UINT64_TYPE__ rbx __asm__("rbx");
2020
register __UINT64_TYPE__ rbp __asm__("rbp");
2121
register __UINT64_TYPE__ r12 __asm__("r12");
@@ -38,9 +38,6 @@ LLVM_LIBC_FUNCTION(void, longjmp, (__jmp_buf * buf, int val)) {
3838
LIBC_INLINE_ASM("mov %1, %0\n\t" : "=r"(r15) : "m"(buf->r15) :);
3939
LIBC_INLINE_ASM("mov %1, %0\n\t" : "=r"(rsp) : "m"(buf->rsp) :);
4040
LIBC_INLINE_ASM("jmp *%0\n\t" : : "m"(buf->rip));
41-
#else // LIBC_TARGET_ARCH_IS_X86_64
42-
#error "longjmp implementation not available for the target architecture."
43-
#endif
4441
}
4542

4643
} // namespace __llvm_libc

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