[PATCH] Fix ICE in rewrite_expr_tree_parallel

["Cui, Lili" <lili.cui@intel.com>]

Hi,

This patch is to fix ICE in rewrite_expr_tree_parallel.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110038

Bootstrapped and regtested. Ok for trunk?

Regards
Lili.

1. Limit the value of tree-reassoc-width to IntegerRange(0, 256).
2. Add width limit in rewrite_expr_tree_parallel.

gcc/ChangeLog:

	PR tree-optimization/110038
	* params.opt: Add a limit on tree-reassoc-width.
	* tree-ssa-reassoc.cc
	(rewrite_expr_tree_parallel): Add width limit.

gcc/testsuite/ChangeLog:

	PR tree-optimization/110038
	* gcc.dg/pr110038.c: New test.
---
 gcc/params.opt                  |  2 +-
 gcc/testsuite/gcc.dg/pr110038.c | 10 ++++++++++
 gcc/tree-ssa-reassoc.cc         |  3 +++
 3 files changed, 14 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.dg/pr110038.c

diff --git a/gcc/params.opt b/gcc/params.opt
index 66f1c99036a..70cfb495e3a 100644
--- a/gcc/params.opt
+++ b/gcc/params.opt
@@ -1091,7 +1091,7 @@ Common Joined UInteger Var(param_tracer_min_branch_ratio) Init(10) IntegerRange(
 Stop reverse growth if the reverse probability of best edge is less than this threshold (in percent).
 
 -param=tree-reassoc-width=
-Common Joined UInteger Var(param_tree_reassoc_width) Param Optimization
+Common Joined UInteger Var(param_tree_reassoc_width) IntegerRange(0, 256) Param Optimization
 Set the maximum number of instructions executed in parallel in reassociated tree.  If 0, use the target dependent heuristic.
 
 -param=tsan-distinguish-volatile=
diff --git a/gcc/testsuite/gcc.dg/pr110038.c b/gcc/testsuite/gcc.dg/pr110038.c
new file mode 100644
index 00000000000..0f578b182ca
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr110038.c
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+/* { dg-options "-O --param=tree-reassoc-width=256" } */
+
+unsigned a, b;
+
+void
+foo (unsigned c)
+{
+  a += b + c + 1;
+}
diff --git a/gcc/tree-ssa-reassoc.cc b/gcc/tree-ssa-reassoc.cc
index ad2f528ff07..f8055d59d57 100644
--- a/gcc/tree-ssa-reassoc.cc
+++ b/gcc/tree-ssa-reassoc.cc
@@ -5510,6 +5510,9 @@ rewrite_expr_tree_parallel (gassign *stmt, int width, bool has_fma,
   for (i = stmt_num - 2; i >= 0; i--)
     stmts[i] = SSA_NAME_DEF_STMT (gimple_assign_rhs1 (stmts[i+1]));
 
+   /* Width should not be larger than op_num/2.  */
+   width = width <= op_num / 2 ? width : op_num / 2;
+
   /* Build parallel dependency chain according to width.  */
   for (i = 0; i < width; i++)
     {
-- 
2.25.1