Attachment 56161 Details for Bug 131700

testcase - -O1 or higher exposes the bug, -O0 works fine

ntp.c (text/plain), 1.56 KB, created by Dirk Mueller on 2005-11-01 17:59:29 UTC

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Creator: Dirk Mueller

Created: 2005-11-01 17:59:29 UTC

Size: 1.56 KB

patch

obsolete

>#include <assert.h>
>#include <stdio.h>
>
>typedef unsigned int u_int32;
>
>typedef struct {
>        union {
>                u_int32 Xl_ui;
>        } Ul_i;
>        union {
>                u_int32 Xl_uf;
>        } Ul_f;
>} l_fp;
>
>#define l_ui    Ul_i.Xl_ui
>#define l_uf    Ul_f.Xl_uf
>
>#define M_LSHIFT(v_i, v_f)              /* v <<= 1 */ \
>        do { \
>                (v_i) <<= 1; \
>                if ((v_f) & 0x80000000) \
>                        (v_i) |= 0x1; \
>                (v_f) <<= 1; \
>        } while (0)
>
>#define M_ADD(r_i, r_f, a_i, a_f)       /* r += a */ \
>        do { \
>                u_int32 lo_tmp; \
>                u_int32 hi_tmp; \
>                \
>                lo_tmp = ((r_f) & 0xffff) + ((a_f) & 0xffff); \
>                hi_tmp = (((r_f) >> 16) & 0xffff) + (((a_f) >> 16) & 0xffff); \
>                if (lo_tmp & 0x10000) \
>                        hi_tmp++; \
>                (r_f) = ((hi_tmp & 0xffff) << 16) | (lo_tmp & 0xffff); \
>                \
>                (r_i) += (a_i); \
>                if (hi_tmp & 0x10000) \
>                        (r_i)++; \
>        } while (0)
>
>
>void dolfptoa(short ndec)
>{
>	l_fp work;
>
>	work.l_ui = 0;
>	work.l_uf = 0x535f3d8;
>	while (ndec > 0) {
>	 		l_fp ftmp;
>
>			ndec--;
>			work.l_ui = 0;
>			M_LSHIFT(work.l_ui, work.l_uf);
>			printf("%d\t", work.l_ui);
>			ftmp = work;
>			M_LSHIFT(work.l_ui, work.l_uf);
>			M_LSHIFT(work.l_ui, work.l_uf);
>			printf("%d\t", work.l_ui);
>			M_ADD(work.l_ui, work.l_uf, ftmp.l_ui, ftmp.l_uf);
>			printf("%d\n", work.l_ui);
>			assert(work.l_ui < 10);
>	}
>}
>
>int main()
>{
>  dolfptoa(6);
>
>  return 0;
>}

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Attachments on bug 131700: 56161