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tree-optimization/104064 - UBSAN issue in vect dataref analysis 

Since we order DRs after DR_INIT we know the difference will be
positive and thus can avoid signed overflow issues by using
unsigned arithmetic to produce the known unsigned result.

2022-01-18  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/104064
	* tree-vect-data-refs.cc (vect_analyze_data_ref_accesses): Check
	DR_INIT fits in a signed HWI, represent the difference from the
	first DR in unsigned.
This commit is contained in:
Richard Biener 2022-01-18 09:06:13 +01:00
parent ff7aeceb6b
commit 00dc7877ee
1 changed files with 9 additions and 6 deletions
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15
gcc/tree-vect-data-refs.cc
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@ -3172,8 +3172,8 @@ vect_analyze_data_ref_accesses (vec_info *vinfo,
break;
/* Check that the DR_INITs are compile-time constants. */
if (TREE_CODE (DR_INIT (dra)) != INTEGER_CST
|| TREE_CODE (DR_INIT (drb)) != INTEGER_CST)
if (!tree_fits_shwi_p (DR_INIT (dra))
|| !tree_fits_shwi_p (DR_INIT (drb)))
break;
/* Different .GOMP_SIMD_LANE calls still give the same lane,
@ -3203,15 +3203,18 @@ vect_analyze_data_ref_accesses (vec_info *vinfo,
{
/* If init_b == init_a + the size of the type * k, we have an
interleaving, and DRA is accessed before DRB. */
HOST_WIDE_INT type_size_a = tree_to_uhwi (sza);
unsigned HOST_WIDE_INT type_size_a = tree_to_uhwi (sza);
if (type_size_a == 0
|| (init_b - init_a) % type_size_a != 0)
|| (((unsigned HOST_WIDE_INT)init_b - init_a)
% type_size_a != 0))
break;
/* If we have a store, the accesses are adjacent. This splits
groups into chunks we support (we don't support vectorization
of stores with gaps). */
if (!DR_IS_READ (dra) && init_b - init_prev != type_size_a)
if (!DR_IS_READ (dra)
&& (((unsigned HOST_WIDE_INT)init_b - init_prev)
!= type_size_a))
break;
/* If the step (if not zero or non-constant) is smaller than the
@ -3222,7 +3225,7 @@ vect_analyze_data_ref_accesses (vec_info *vinfo,
unsigned HOST_WIDE_INT step
= absu_hwi (tree_to_shwi (DR_STEP (dra)));
if (step != 0
&& step <= (unsigned HOST_WIDE_INT)(init_b - init_a))
&& step <= ((unsigned HOST_WIDE_INT)init_b - init_a))
break;
}
}