From 9e95992f9ac7c5ed3d53cd720626e791e2b07004 Mon Sep 17 00:00:00 2001 From: Nick Desaulniers Date: Fri, 5 Apr 2024 15:40:55 -0700 Subject: [PATCH] [libc][setjmp] fix setjmp test This would consistently fail for me locally, to the point where I could not run `ninja libc-unit-tests` without `ninja libc_setjmp_unittests` failing. Turns out that since I enabled -ftrivial-auto-var-init=pattern in commit 1d5c16d78058 ("[libc] default enable -ftrivial-auto-var-init=pattern (#78776)") this has been a problem. Our x86_64 setjmp definition disabled -Wuninitialized, so we wound up clobbering these registers and instead backing up 0xAAAAAAAAAAAAAAAA rather than the actual register value. --- libc/src/setjmp/x86_64/setjmp.cpp | 23 +++++++---------------- 1 file changed, 7 insertions(+), 16 deletions(-) diff --git a/libc/src/setjmp/x86_64/setjmp.cpp b/libc/src/setjmp/x86_64/setjmp.cpp index 8b6981d4cc34a2..bbc08d42bfd617 100644 --- a/libc/src/setjmp/x86_64/setjmp.cpp +++ b/libc/src/setjmp/x86_64/setjmp.cpp @@ -16,22 +16,13 @@ namespace LIBC_NAMESPACE { LLVM_LIBC_FUNCTION(int, setjmp, (__jmp_buf * buf)) { - register __UINT64_TYPE__ rbx __asm__("rbx"); - register __UINT64_TYPE__ r12 __asm__("r12"); - register __UINT64_TYPE__ r13 __asm__("r13"); - register __UINT64_TYPE__ r14 __asm__("r14"); - register __UINT64_TYPE__ r15 __asm__("r15"); - - // We want to store the register values as is. So, we will suppress the - // compiler warnings about the uninitialized variables declared above. -#pragma GCC diagnostic push -#pragma GCC diagnostic ignored "-Wuninitialized" - LIBC_INLINE_ASM("mov %1, %0\n\t" : "=m"(buf->rbx) : "r"(rbx) :); - LIBC_INLINE_ASM("mov %1, %0\n\t" : "=m"(buf->r12) : "r"(r12) :); - LIBC_INLINE_ASM("mov %1, %0\n\t" : "=m"(buf->r13) : "r"(r13) :); - LIBC_INLINE_ASM("mov %1, %0\n\t" : "=m"(buf->r14) : "r"(r14) :); - LIBC_INLINE_ASM("mov %1, %0\n\t" : "=m"(buf->r15) : "r"(r15) :); -#pragma GCC diagnostic pop + asm("mov %%rbx, %[rbx]\n\t" + "mov %%r12, %[r12]\n\t" + "mov %%r13, %[r13]\n\t" + "mov %%r14, %[r14]\n\t" + "mov %%r15, %[r15]" + : [rbx] "=m"(buf->rbx), [r12] "=m"(buf->r12), [r13] "=m"(buf->r13), + [r14] "=m"(buf->r14), [r15] "=m"(buf->r15)); // We want the rbp of the caller, which is what __builtin_frame_address(1) // should return. But, compilers generate a warning that calling