在 2021-06-16 00:04, Biswapriyo Nath 写道:
I don't consider myself expert on this topic. But while _exploring_ something, I found these (MxCsr and FpCsr) are missing from JUMP_BUFFER. Is this right? wine also don't have these. Wondering why? Thought attached.
This patch looks correct but is incomplete, because FP and SSE control registers have to be restored in `longjmp.S`.
I actually have a testcase for this which can prove that the UCRTAPP behavior is incorrect. See comments in attached file for details.
-- Best regards, Liu Hao
// Note this testcase does not work on x86.
//
// cl test.c && ./test.exe
// gcc test.c && ./a.exe
// gcc test.c -nodefaultlibs -lmingwex -lmingw32 \
// -lgcc -lgcc_s -lucrtapp -lkernel32 && ./a.exe
//
// Expected outputs:
//
// before setjmp, rounding was set to 0200
// after setjmp, rounding is 0200
// before long jmp, rounding was set to 0100
// after longjmp, rounding is 0200
#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
#include <float.h>
#include <setjmp.h>
#ifdef _MSC_VER
#pragma fenv_access (on)
#else
#pragma STDC FENV_ACCESS on
#endif
int main(void)
{
jmp_buf buf;
unsigned r;
r = _controlfp(_RC_UP, _MCW_RC);
printf("before setjmp, rounding was set to %.4x\n", r & _MCW_RC);
if(setjmp(buf) == 0) {
r = _controlfp(0, 0);
printf("after setjmp, rounding is %.4x\n", r & _MCW_RC);
r = _controlfp(_RC_DOWN, _MCW_RC);
printf("before long jmp, rounding was set to %.4x\n", r & _MCW_RC);
longjmp(buf, 1);
}
r = _controlfp(0, 0);
printf("after longjmp, rounding is %.4x\n", r & _MCW_RC);
}
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