From a7e706df2280de4a42f68b6c44401e4348d3593c Mon Sep 17 00:00:00 2001
From: Richard Biener <rguenther@suse.de>
Date: Mon, 20 Feb 2023 12:58:50 +0100
Subject: [PATCH] tree-optimization/108793 - niter compute type mismatch
When computing the number of iterations until wrap types are mixed up,
eventually leading to checking ICEs with a pointer bitwise inversion.
The following uses niter_type for the calculation.
PR tree-optimization/108793
* tree-ssa-loop-niter.cc (number_of_iterations_until_wrap):
Use convert operands to niter_type when computing num.
* gcc.dg/torture/pr108793.c: New testcase.
---
gcc/testsuite/gcc.dg/torture/pr108793.c | 10 ++++++++++
gcc/tree-ssa-loop-niter.cc | 11 ++++++-----
2 files changed, 16 insertions(+), 5 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/torture/pr108793.c
diff --git a/gcc/testsuite/gcc.dg/torture/pr108793.c b/gcc/testsuite/gcc.dg/torture/pr108793.c
new file mode 100644
index 000000000000..83973eb05d90
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr108793.c
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+
+typedef int *p;
+extern p a[], b[];
+int f () {
+ int n = 0;
+ for (p* i = &a[0]; i > &b[0]; i++)
+ n++;
+ return n;
+}
diff --git a/gcc/tree-ssa-loop-niter.cc b/gcc/tree-ssa-loop-niter.cc
index 1ce5e736ce39..dc4c7a418f64 100644
--- a/gcc/tree-ssa-loop-niter.cc
+++ b/gcc/tree-ssa-loop-niter.cc
@@ -1494,8 +1494,9 @@ number_of_iterations_until_wrap (class loop *loop, tree type, affine_iv *iv0,
if (integer_zerop (assumptions))
return false;
- num = fold_build2 (MINUS_EXPR, niter_type, wide_int_to_tree (type, max),
- iv1->base);
+ num = fold_build2 (MINUS_EXPR, niter_type,
+ wide_int_to_tree (niter_type, max),
+ fold_convert (niter_type, iv1->base));
/* When base has the form iv + 1, if we know iv >= n, then iv + 1 < n
only when iv + 1 overflows, i.e. when iv == TYPE_VALUE_MAX. */
@@ -1531,8 +1532,9 @@ number_of_iterations_until_wrap (class loop *loop, tree type, affine_iv *iv0,
if (integer_zerop (assumptions))
return false;
- num = fold_build2 (MINUS_EXPR, niter_type, iv0->base,
- wide_int_to_tree (type, min));
+ num = fold_build2 (MINUS_EXPR, niter_type,
+ fold_convert (niter_type, iv0->base),
+ wide_int_to_tree (niter_type, min));
low = min;
if (TREE_CODE (iv0->base) == INTEGER_CST)
high = wi::to_wide (iv0->base) + 1;
@@ -1546,7 +1548,6 @@ number_of_iterations_until_wrap (class loop *loop, tree type, affine_iv *iv0,
/* (delta + step - 1) / step */
step = fold_convert (niter_type, step);
- num = fold_convert (niter_type, num);
num = fold_build2 (PLUS_EXPR, niter_type, num, step);
niter->niter = fold_build2 (FLOOR_DIV_EXPR, niter_type, num, step);
--
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