Various 32-bit targets show failures in gcc.dg/analyzer/data-model-1.c
with tests of the form:
__analyzer_eval (q[-2].x == 107024); /* { dg-warning "TRUE" } */
__analyzer_eval (q[-2].y == 107025); /* { dg-warning "TRUE" } */
where they emit UNKNOWN instead.
The root cause is that gimple has a byte-based twos-complement offset
of -16 expressed like this:
_55 = q_92 + 4294967280; (32-bit)
or:
_55 = q_92 + 18446744073709551600; (64-bit)
Within region_model::convert_byte_offset_to_array_index that unsigned
offset was being divided by the element size to get an offset within
an array.
This happened to work on 64-bit target and host, but not elsewhere;
the offset needs to be converted to a signed type before the division
is meaningful.
This patch does so, fixing the failures.
Successfully bootstrapped & regrtested on x86_64-pc-linux-gnu;
verified with -m32 and -m64.
OK for master?
gcc/analyzer/ChangeLog:
PR analyzer/93281
* region-model.cc
(region_model::convert_byte_offset_to_array_index): Convert
offset_cst to ssizetype before dividing by byte_size.
---
gcc/analyzer/region-model.cc | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/gcc/analyzer/region-model.cc b/gcc/analyzer/region-model.cc
index 5c39be4fd7f..b62ddf82a40 100644
--- a/gcc/analyzer/region-model.cc
+++ b/gcc/analyzer/region-model.cc
@@ -6414,9 +6414,12 @@ region_model::convert_byte_offset_to_array_index (tree
ptr_type,
/* This might not be a constant. */
tree byte_size = size_in_bytes (elem_type);
+ /* Ensure we're in a signed representation before doing the division. */
+ tree signed_offset_cst = fold_convert (ssizetype, offset_cst);
+
tree index
= fold_build2 (TRUNC_DIV_EXPR, integer_type_node,
- offset_cst, byte_size);
+ signed_offset_cst, byte_size);
if (CONSTANT_CLASS_P (index))
return get_or_create_constant_svalue (index);
--
2.21.0
