https://bugs.kde.org/show_bug.cgi?id=392180
Bug ID: 392180
Summary: LTO build simplification: __asm__ in m_libcsetjmp.c
Product: valgrind
Version: unspecified
Platform: Other
OS: Linux
Status: UNCONFIRMED
Severity: normal
Priority: NOR
Component: general
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
gcc puts __asm__ code within a function into a different partition, compared to
__asm__code outside of functions
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84861). This means, that with
Link-Time-Optimization the __asm__ outside of functions, defining a function,
is not callable from other object files.
commit ab773096d "Fix 338252 - building valgrind with -flto (link time
optimisation) fails" compiles for this reason coregrind/m_libcsetjmp.c and
coregrind/m_main.c explicitly without -flto.
The compilation process will be much easier, if m_libcsetjmp.c defines the
functions VG_MINIMAL_LONGJMP and VG_MINIMAL_SETJMP outside of __asm__ as
suggested at the above link. (I guess the code will then also be easier to
read and maintain).
Evaluate the change below, apply something similar to the other targets and for
m_main.c, and remove in coregrind/Makefile.am the with/without -lflto
distinction logic when compiling m_libcsetjmp.c and m_main.c.
Consider also the discussion at https://bugs.kde.org/show_bug.cgi?id=338252 .
diff --git a/coregrind/m_libcsetjmp.c b/coregrind/m_libcsetjmp.c
index 68c101e..5626748 100644
--- a/coregrind/m_libcsetjmp.c
+++ b/coregrind/m_libcsetjmp.c
@@ -382,25 +382,10 @@ __asm__(
#if defined(VGP_amd64_linux) || defined(VGP_amd64_darwin) || \
defined(VGP_amd64_solaris)
-__asm__(
-".text" "\n"
-"" "\n"
-
-#if defined(VGP_amd64_linux) || defined(VGP_amd64_solaris)
-".global VG_MINIMAL_SETJMP" "\n" // rdi = jmp_buf
-"VG_MINIMAL_SETJMP:" "\n"
-
-#elif defined(VGP_amd64_darwin)
-".globl _VG_MINIMAL_SETJMP" "\n" // rdi = jmp_buf
-"_VG_MINIMAL_SETJMP:" "\n"
+__attribute__((returns_twice))
+UWord VG_MINIMAL_SETJMP(VG_MINIMAL_JMP_BUF(_env)) {
-#else
-# error "Huh?"
-#endif
-
-" movq %rax, 0(%rdi)" "\n"
-" movq %rbx, 8(%rdi)" "\n"
-" movq %rcx, 16(%rdi)" "\n"
+__asm__(
" movq %rdx, 24(%rdi)" "\n"
" movq %rdi, 32(%rdi)" "\n"
" movq %rsi, 40(%rdi)" "\n"
@@ -421,22 +406,13 @@ __asm__(
" movq $0, %rax" "\n"
" ret" "\n"
"" "\n"
+ );
+}
-
-#if defined(VGP_amd64_linux) || defined(VGP_amd64_solaris)
-".global VG_MINIMAL_LONGJMP" "\n"
-"VG_MINIMAL_LONGJMP:" "\n" // rdi = jmp_buf
-
-#elif defined(VGP_amd64_darwin)
-".globl _VG_MINIMAL_LONGJMP" "\n"
-"_VG_MINIMAL_LONGJMP:" "\n" // rdi = jmp_buf
-
-#else
-# error "Huh?"
-#endif
+__attribute__((noreturn))
+void VG_MINIMAL_LONGJMP(VG_MINIMAL_JMP_BUF(_env)) {
+ __asm__(
// skip restoring rax; it's pointless
-" movq 8(%rdi), %rbx" "\n"
-" movq 16(%rdi), %rcx" "\n"
" movq 24(%rdi), %rdx" "\n"
// defer restoring rdi; we still need it
" movq 40(%rdi), %rsi" "\n"
@@ -465,12 +441,8 @@ __asm__(
// address space.
" jmp *%rax" "\n"
"" "\n"
-
-#if !defined(VGP_amd64_darwin)
-".previous" "\n"
-#endif
-);
-
+ );
+}
#endif /* VGP_amd64_linux || VGP_amd64_darwin || VGP_amd64_solaris */
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