SPARC32-bit SDIV of negative divisor gives wrong result
Host environment
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Operating system: - any -
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OS/kernel version:
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Architecture:
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QEMU flavor:
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QEMU version: 9.0.00
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QEMU command line:
qemu-system-sparc -M SS-5 -m 256 -drive file=sparc.qcow2,bus=0,unit=0,media=disk -drive file=solaris_7_1199_sparc.iso,bus=0,unit=2,media=cdrom,readonly=on -nographic -net nic,macaddr=52:54:0:12:34:58 -net tap,ifname=tap5,script=no,downscript=noEmulated/Virtualized environment -
Operating system:
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OS/kernel version:
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Architecture: SPARC
Description of problem
SDIV of negative divisor gives wrong result because of typo in helper_sdiv(). This is true for QEMU 9.0.0 and earlier.
Place -1 in the Y register and -128 in another reg, then -120 in another register and do SDIV into a result register, instead of the proper value of 1 for the result, the incorrect value of 0 is produced.
There is a typo in target/sparc/helper.c that causes the divisor to be consider unsigned, this patch fixes it:
*** helper.c.ori Tue Apr 23 16:23:45 2024 --- helper.c Mon Apr 29 20:14:07 2024
*** 121,127 **** return (uint32_t)(b32 < 0 ? INT32_MAX : INT32_MIN) | (-1ull << 32); }
! a64 /= b; r = a64; if (unlikely(r != a64)) { return (uint32_t)(a64 < 0 ? INT32_MIN : INT32_MAX) | (-1ull << 32); --- 121,127 ---- return (uint32_t)(b32 < 0 ? INT32_MAX : INT32_MIN) | (-1ull << 32); }
! a64 /= b32; r = a64; if (unlikely(r != a64)) { return (uint32_t)(a64 < 0 ? INT32_MIN : INT32_MAX) | (-1ull << 32);