From: Richard Biener <rguenther@suse.de>
Date: Mon, 6 Oct 2025 07:06:45 +0000 (+0200)
Subject: tree-optimization/122158 - vector reduction epilog for bit-precision result
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=1f1cd723c52deca6ea9aaa8c2b54e6c5b6478008;p=thirdparty%2Fgcc.git

tree-optimization/122158 - vector reduction epilog for bit-precision result

The following makes sure to perform the vector element extraction
using the element type and convert to the original, possibly
bit-precision, result afterwards.  I've also used gimple_build
for the BIT_FIELD_REF since that simplifies the code.

	PR tree-optimization/122158
	* tree-vect-loop.cc (vect_create_epilog_for_reduction): Handle
	bit-precision result.

	* gcc.dg/vect/pr122158.c: New testcase.
---

diff --git a/gcc/testsuite/gcc.dg/vect/pr122158.c b/gcc/testsuite/gcc.dg/vect/pr122158.c
new file mode 100644
index 00000000000..5d0f7dac7dc
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr122158.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+
+int g_3, g_181, g_7;
+void func_54(unsigned int, int *);
+int func_24()
+{
+  int p_25;
+  int *l_49 = &g_3;
+  func_54(g_7, l_49);
+}
+void func_54(unsigned int p_55, int *p_56)
+{
+  for (g_181 = 27; g_181 != 9; --g_181)
+    p_55 || (*p_56 = 0);
+}
diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index df45adbe035..73398e58fdc 100644
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -6049,8 +6049,6 @@ vect_create_epilog_for_reduction (loop_vec_info loop_vinfo,
                   Create:  va = vop <va, va'>
                 }  */
 
-          tree rhs;
-
           if (dump_enabled_p ())
             dump_printf_loc (MSG_NOTE, vect_location,
 			     "Reduce using vector shifts\n");
@@ -6069,7 +6067,6 @@ vect_create_epilog_for_reduction (loop_vec_info loop_vinfo,
 	      new_temp = gimple_build (&stmts, code,
 				       vectype1, new_name, new_temp);
             }
-	  gsi_insert_seq_before (&exit_gsi, stmts, GSI_SAME_STMT);
 
 	  /* 2.4  Extract the final scalar result.  Create:
 	     s_out3 = extract_field <v_out2, bitpos>  */
@@ -6078,12 +6075,11 @@ vect_create_epilog_for_reduction (loop_vec_info loop_vinfo,
 	    dump_printf_loc (MSG_NOTE, vect_location,
 			     "extract scalar result\n");
 
-	  rhs = build3 (BIT_FIELD_REF, scalar_type, new_temp,
-			bitsize, bitsize_zero_node);
-	  epilog_stmt = gimple_build_assign (new_scalar_dest, rhs);
-	  new_temp = make_ssa_name (new_scalar_dest, epilog_stmt);
-	  gimple_assign_set_lhs (epilog_stmt, new_temp);
-	  gsi_insert_before (&exit_gsi, epilog_stmt, GSI_SAME_STMT);
+	  new_temp = gimple_build (&stmts, BIT_FIELD_REF, TREE_TYPE (vectype1),
+				   new_temp, bitsize, bitsize_zero_node);
+	  new_temp = gimple_build (&stmts, VIEW_CONVERT_EXPR,
+				   scalar_type, new_temp);
+	  gsi_insert_seq_before (&exit_gsi, stmts, GSI_SAME_STMT);
 	  scalar_results.safe_push (new_temp);
         }
       else