PR tree-optimization/22236

	* tree-cfg.c (print_pred_bbs, print_succ_bbs): Correctly print
	successors and predecessors.
	* tree-chrec.c (chrec_convert): Before converting, check that
	sequences don't wrap.
	* tree-data-ref.c (compute_estimated_nb_iterations): Moved ...
	(analyze_array): Extern.
	(find_data_references_in_loop): Remove call to
	compute_estimated_nb_iterations.
	* tree-data-ref.h (analyze_array): Declared.
	* tree-flow-inline.h (single_ssa_tree_operand, single_ssa_use_operand,
	single_ssa_def_operand, zero_ssa_operands): Fix documentation.
	* tree-flow.h (scev_probably_wraps_p): Declare with an extra parameter.
	* tree-scalar-evolution.c (instantiate_parameters_1): Factor entry
	condition.
	* tree-ssa-loop-ivcanon.c: Fix documentation.
	* tree-ssa-loop-ivopts.c (idx_find_step): Add a fixme note.
	* tree-ssa-loop-niter.c (compute_estimated_nb_iterations): ... here.
	(infer_loop_bounds_from_undefined): New.
	(estimate_numbers_of_iterations_loop): Use
	infer_loop_bounds_from_undefined.
	(used_in_pointer_arithmetic_p): New.
	(scev_probably_wraps_p): Pass an extra parameter.  Call
	used_in_pointer_arithmetic_p.  Check that AT_STMT is not null.
	(convert_step): Fix documentation.
	* tree-vrp.c (adjust_range_with_scev): Call instantiate_parameters.
	Use initial_condition_in_loop_num and evolution_part_in_loop_num
	instead of CHREC_LEFT and CHREC_RIGHT.  Adjust the call to
	scev_probably_wraps_p.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@103055 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 33 insertions, 0 deletions

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr22236.c b/gcc/testsuite/gcc.dg/tree-ssa/pr22236.c
new file mode 100644
index 00000000000..1986c2f0cfe
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr22236.c
@@ -0,0 +1,33 @@
+/* { dg-do run } */
+/* { dg-options "-O1 -fno-tree-vrp -fwrapv" } */
+
+/* PR tree-optimization/22236
+
+    Avoid conversion of (signed char) {(uchar)1, +, (uchar)1}_x when
+    it is not possible to prove that the scev does not wrap.  
+
+    In this PR, a sequence 1, 2, ..., 255 has to be converted to
+    signed char, but this would wrap: 1, 2, ..., 127, -128, ...  The
+    result should not be a linear scev {(schar)1, +, (schar)1}_x.
+    The conversion should be kept: (schar) {(uchar)1, +, (uchar)1}_x.
+ */
+
+void abort(void);
+
+static inline void
+foo (signed char a)
+{
+  int b = a - 0x7F;
+  if (b > 1)
+    abort();
+}
+
+int main()
+{
+  unsigned char b;
+  for(b = 0; b < 0xFF; b++)
+    foo (b);
+
+  return 0;
+}
+