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Fix undefined behavior spotted by the sanitizer

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gcc/
	PR rtl-optimization/99376
	* rtlanal.c (nonzero_bits1) <arithmetic operators>: If the number
	of low-order zero bits is too large, set the result to 0 directly.
This commit is contained in:
Eric Botcazou 2021-03-05 12:38:49 +01:00
parent 6ddedd3efa
commit 28354bc22b
1 changed files with 7 additions and 1 deletions
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8
gcc/rtlanal.c
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@ -5053,11 +5053,17 @@ nonzero_bits1 (const_rtx x, scalar_int_mode mode, const_rtx known_x,
gcc_unreachable ();
}
/* Note that mode_width <= HOST_BITS_PER_WIDE_INT, see above. */
if (result_width < mode_width)
nonzero &= (HOST_WIDE_INT_1U << result_width) - 1;
if (result_low > 0)
nonzero &= ~((HOST_WIDE_INT_1U << result_low) - 1);
{
if (result_low < HOST_BITS_PER_WIDE_INT)
nonzero &= ~((HOST_WIDE_INT_1U << result_low) - 1);
else
nonzero = 0;
}
}
break;