diff options
Diffstat (limited to 'contrib/guix/patches/gcc-broken-longjmp.patch')
| -rw-r--r-- | contrib/guix/patches/gcc-broken-longjmp.patch | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/contrib/guix/patches/gcc-broken-longjmp.patch b/contrib/guix/patches/gcc-broken-longjmp.patch new file mode 100644 index 0000000000..1cfc0918b0 --- /dev/null +++ b/contrib/guix/patches/gcc-broken-longjmp.patch @@ -0,0 +1,68 @@ +commit eb5698897c52702498938592d7f76e67d126451f +Author: Eric Botcazou <ebotcazou@adacore.com> +Date: Wed May 5 22:48:51 2021 +0200 + + Fix PR target/100402 + + This is a regression for 64-bit Windows present from mainline down to the 9 + branch and introduced by the fix for PR target/99234. Again SEH, but with + a twist related to the way MinGW implements setjmp/longjmp, which turns out + to be piggybacked on SEH with recent versions of MinGW, i.e. the longjmp + performs a bona-fide unwinding of the stack, because it calls RtlUnwindEx + with the second argument initially passed to setjmp, which is the result of + __builtin_frame_address (0) in the MinGW header file: + + define setjmp(BUF) _setjmp((BUF), __builtin_frame_address (0)) + + This means that we directly expose the frame pointer to the SEH machinery + here (unlike with regular exception handling where we use an intermediate + CFA) and thus that we cannot do whatever we want with it. The old code + would leave it unaligned, i.e. not multiple of 16, whereas the new code + aligns it, but this breaks for some reason; at least it appears that a + .seh_setframe directive with 0 as second argument always works, so the + fix aligns it this way. + + gcc/ + PR target/100402 + * config/i386/i386.c (ix86_compute_frame_layout): For a SEH target, + always return the establisher frame for __builtin_frame_address (0). + gcc/testsuite/ + * gcc.c-torture/execute/20210505-1.c: New test. + +diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c +index 2f838840e96..06ad1b2274e 100644 +--- a/gcc/config/i386/i386.c ++++ b/gcc/config/i386/i386.c +@@ -6356,12 +6356,29 @@ ix86_compute_frame_layout (void) + area, see the SEH code in config/i386/winnt.c for the rationale. */ + frame->hard_frame_pointer_offset = frame->sse_reg_save_offset; + +- /* If we can leave the frame pointer where it is, do so. Also, return ++ /* If we can leave the frame pointer where it is, do so; however return + the establisher frame for __builtin_frame_address (0) or else if the +- frame overflows the SEH maximum frame size. */ ++ frame overflows the SEH maximum frame size. ++ ++ Note that the value returned by __builtin_frame_address (0) is quite ++ constrained, because setjmp is piggybacked on the SEH machinery with ++ recent versions of MinGW: ++ ++ # elif defined(__SEH__) ++ # if defined(__aarch64__) || defined(_ARM64_) ++ # define setjmp(BUF) _setjmp((BUF), __builtin_sponentry()) ++ # elif (__MINGW_GCC_VERSION < 40702) ++ # define setjmp(BUF) _setjmp((BUF), mingw_getsp()) ++ # else ++ # define setjmp(BUF) _setjmp((BUF), __builtin_frame_address (0)) ++ # endif ++ ++ and the second argument passed to _setjmp, if not null, is forwarded ++ to the TargetFrame parameter of RtlUnwindEx by longjmp (after it has ++ built an ExceptionRecord on the fly describing the setjmp buffer). */ + const HOST_WIDE_INT diff + = frame->stack_pointer_offset - frame->hard_frame_pointer_offset; +- if (diff <= 255) ++ if (diff <= 255 && !crtl->accesses_prior_frames) + { + /* The resulting diff will be a multiple of 16 lower than 255, + i.e. at most 240 as required by the unwind data structure. */ |