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Fix PR78588 - rtlanal.c:5210:38: runtime error: shift exponent 4294967295 is too large for 64-bit type 

Building gcc with -fsanitize=undefined shows:
 rtlanal.c:5210:38: runtime error: shift exponent 4294967295 is too large for 64-bit type 'long unsigned int'

This happens because if_then_else_cond() in combine.c calls
num_sign_bit_copies() in rtlanal.c with mode==BLKmode.

5205   bitwidth = GET_MODE_PRECISION (mode);
5206   if (bitwidth > HOST_BITS_PER_WIDE_INT)
5207     return 1;
5208
5209   nonzero = nonzero_bits (x, mode);
5210   return nonzero & (HOST_WIDE_INT_1U << (bitwidth - 1))
5211          ? 1 : bitwidth - floor_log2 (nonzero) - 1;

This causes (bitwidth - 1) to wrap around.

	PR rtl-optimization/78588
	* combine.c (if_then_else_cond): Also guard against BLKmode.
	* rtlanal.c (num_sign_bit_copies1): Add assert.

From-SVN: r242997
This commit is contained in:
Markus Trippelsdorf 2016-11-30 07:30:55 +00:00 committed by Markus Trippelsdorf
parent a4f15a7d45
commit ced17de640
3 changed files with 9 additions and 1 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2016-11-30 Markus Trippelsdorf <markus@trippelsdorf.de>
PR rtl-optimization/78588
* combine.c (if_then_else_cond): Also guard against BLKmode.
* rtlanal.c (num_sign_bit_copies1): Add assert.
2016-11-29 Jeff Law <law@redhat.com>
* common/config/arc/arc-common.c (arc_handle_option): Remove unused

2
gcc/combine.c
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@ -9176,7 +9176,7 @@ if_then_else_cond (rtx x, rtx *ptrue, rtx *pfalse)
/* If X is known to be either 0 or -1, those are the true and
false values when testing X. */
else if (x == constm1_rtx || x == const0_rtx
|| (mode != VOIDmode
|| (mode != VOIDmode && mode != BLKmode
&& num_sign_bit_copies (x, mode) == GET_MODE_PRECISION (mode)))
{
*ptrue = constm1_rtx, *pfalse = const0_rtx;

2
gcc/rtlanal.c
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@ -4840,6 +4840,8 @@ num_sign_bit_copies1 (const_rtx x, machine_mode mode, const_rtx known_x,
if (mode == VOIDmode)
mode = GET_MODE (x);
gcc_checking_assert (mode != BLKmode);
if (mode == VOIDmode || FLOAT_MODE_P (mode) || FLOAT_MODE_P (GET_MODE (x))
|| VECTOR_MODE_P (GET_MODE (x)) || VECTOR_MODE_P (mode))
return 1;