From: Richard Biener <rguenther@suse.de>
Date: Tue, 17 Feb 2026 10:05:45 +0000 (+0100)
Subject: tree-optimization/124132 - fix type problem in loop splitting
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9a5ee941a2cc525811748f78d42a36d1100c12d7;p=thirdparty%2Fgcc.git

tree-optimization/124132 - fix type problem in loop splitting

The following fixes the computation of the 2nd loop IV bound after
loop splitting when only one of the split IV and the loop control
variable is a pointer.

	PR tree-optimization/124132
	* tree-ssa-loop-split.cc (compute_new_first_bound): Fix
	bound difference computation.

	* gcc.dg/torture/pr124132.c: New testcase.
---

diff --git a/gcc/testsuite/gcc.dg/torture/pr124132.c b/gcc/testsuite/gcc.dg/torture/pr124132.c
new file mode 100644
index 00000000000..8d14fc0346d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr124132.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-w" } */
+
+char slow_mul1_dst1, code_some_shards___gf_mulc__0, code_some_shards_lim;
+long slow_mul1_dst_max;
+long long code_some_shards_pos;
+void code_some_shards()
+{
+  char *dst = &slow_mul1_dst1;
+  for (; dst < &code_some_shards_lim; dst++)
+    {
+      if (code_some_shards_pos < slow_mul1_dst_max)
+        *dst = code_some_shards___gf_mulc__0;
+      code_some_shards_pos += 1;
+    }
+}
diff --git a/gcc/tree-ssa-loop-split.cc b/gcc/tree-ssa-loop-split.cc
index ba6cc45d7f0..722383a420a 100644
--- a/gcc/tree-ssa-loop-split.cc
+++ b/gcc/tree-ssa-loop-split.cc
@@ -458,21 +458,15 @@ compute_new_first_bound (gimple_seq *stmts, class tree_niter_desc *niter,
   tree end = force_gimple_operand (niter->bound, &stmts2,
 					true, NULL_TREE);
   gimple_seq_add_seq_without_update (stmts, stmts2);
-  if (POINTER_TYPE_P (TREE_TYPE (enddiff)))
-    {
-      tree tem = gimple_convert (stmts, sizetype, enddiff);
-      tem = gimple_build (stmts, NEGATE_EXPR, sizetype, tem);
-      enddiff = gimple_build (stmts, POINTER_PLUS_EXPR,
-			      TREE_TYPE (enddiff),
-			      end, tem);
-    }
+  if (POINTER_TYPE_P (TREE_TYPE (controlbase)))
+    enddiff = gimple_build (stmts, POINTER_DIFF_EXPR,
+			    ssizetype, end, enddiff);
   else
     enddiff = gimple_build (stmts, MINUS_EXPR, TREE_TYPE (enddiff),
 			    end, enddiff);
 
   /* Compute guard_init + (end-beg).  */
   tree newbound;
-  enddiff = gimple_convert (stmts, TREE_TYPE (guard_init), enddiff);
   if (POINTER_TYPE_P (TREE_TYPE (guard_init)))
     {
       enddiff = gimple_convert (stmts, sizetype, enddiff);
@@ -481,8 +475,11 @@ compute_new_first_bound (gimple_seq *stmts, class tree_niter_desc *niter,
 			       guard_init, enddiff);
     }
   else
-    newbound = gimple_build (stmts, PLUS_EXPR, TREE_TYPE (guard_init),
-			     guard_init, enddiff);
+    {
+      enddiff = gimple_convert (stmts, TREE_TYPE (guard_init), enddiff);
+      newbound = gimple_build (stmts, PLUS_EXPR, TREE_TYPE (guard_init),
+			       guard_init, enddiff);
+    }
 
   /* Depending on the direction of the IVs the new bound for the first
      loop is the minimum or maximum of old bound and border.