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* [gcc r13-4405] tree-chrec: Fix up ICE on pointer multiplication [PR107835]
@ 2022-11-30 10:46 Jakub Jelinek
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From: Jakub Jelinek @ 2022-11-30 10:46 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:7716ee1e90412f785cba20acffd59fc7461302cb
commit r13-4405-g7716ee1e90412f785cba20acffd59fc7461302cb
Author: Jakub Jelinek <jakub@redhat.com>
Date: Wed Nov 30 11:44:27 2022 +0100
tree-chrec: Fix up ICE on pointer multiplication [PR107835]
r13-254-gdd3c7873a61019e9 added an optimization for {a, +, a} (x-1),
but as can be seen on the following testcase, the way it is written
where chrec_fold_multiply is called with type doesn't work for pointers:
res = build_int_cst (TREE_TYPE (x), 1);
res = chrec_fold_plus (TREE_TYPE (x), x, res);
res = chrec_convert_rhs (type, res, NULL);
res = chrec_fold_multiply (type, chrecr, res);
while what we were doing before and what is still used if the condition
doesn't match is fine:
res = chrec_convert_rhs (TREE_TYPE (chrecr), x, NULL);
res = chrec_fold_multiply (TREE_TYPE (chrecr), chrecr, res);
res = chrec_fold_plus (type, CHREC_LEFT (chrec), res);
because it performs chrec_fold_multiply on TREE_TYPE (chrecr) and converts
only afterwards.
I think the easiest fix is to ignore the new path for pointer types.
2022-11-30 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/107835
* tree-chrec.cc (chrec_apply): Don't handle "{a, +, a} (x-1)"
as "a*x" if type is a pointer type.
* gcc.c-torture/compile/pr107835.c: New test.
Diff:
---
gcc/testsuite/gcc.c-torture/compile/pr107835.c | 11 +++++++++++
gcc/tree-chrec.cc | 3 ++-
2 files changed, 13 insertions(+), 1 deletion(-)
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr107835.c b/gcc/testsuite/gcc.c-torture/compile/pr107835.c
new file mode 100644
index 00000000000..122beff2f11
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr107835.c
@@ -0,0 +1,11 @@
+/* PR tree-optimization/107835 */
+
+int *
+foo (void)
+{
+ int *x = 0;
+ unsigned n = n;
+ for (; n; --n, ++x)
+ ;
+ return x;
+}
diff --git a/gcc/tree-chrec.cc b/gcc/tree-chrec.cc
index 7321fb9d282..dcf26cbae84 100644
--- a/gcc/tree-chrec.cc
+++ b/gcc/tree-chrec.cc
@@ -622,7 +622,8 @@ chrec_apply (unsigned var,
/* "{a, +, b} (x)" -> "a + b*x". */
else if (operand_equal_p (CHREC_LEFT (chrec), chrecr)
&& TREE_CODE (x) == PLUS_EXPR
- && integer_all_onesp (TREE_OPERAND (x, 1)))
+ && integer_all_onesp (TREE_OPERAND (x, 1))
+ && !POINTER_TYPE_P (type))
{
/* We know the number of iterations can't be negative.
So {a, +, a} (x-1) -> "a*x". */
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