diff mbox series

[vect] : fix prologue peeling dominator updates [PR125509]

Message ID patch-20588-tamar@arm.com
State New
Headers
Series [vect] : fix prologue peeling dominator updates [PR125509] |

Checks

Context Check Description
linaro-tcwg-bot/tcwg_gcc_build--master-arm fail Patch failed to apply

Commit Message

Tamar Christina June 3, 2026, 7:49 a.m. UTC 
  In the change to enable vectorization without needing a scalar epilogue I
disabled the dominators update for prolog peeling with the assumption that since
I don't need to go to rewire the exits when we vectorize the main loop we don't
end up with the complicated merge block for which the updates were needed.

And indeed no test failed.  But it turns out we now get a different form so the
updates are still needed.  The merge block is still a mess so determining
manually who is the new dominator of whom is still quite difficult so I couldn't
simplify the updates.

This re-enabled dominator updates after prolog peeling.

Bootstrapped Regtested on aarch64-none-linux-gnu,
arm-none-linux-gnueabihf, x86_64-pc-linux-gnu
-m32, -m64 and no issues.

Pushed.

Thanks,
Tamar

gcc/ChangeLog:

	PR tree-optimization/125509
	* tree-vect-loop-manip.cc (vect_do_peeling): Re-enable dominators
	update for prolog peeling.

gcc/testsuite/ChangeLog:

	PR tree-optimization/125509
	* gcc.dg/vect/pr125509.c: New test.

---


--
diff mbox series

Patch

diff --git a/gcc/testsuite/gcc.dg/vect/pr125509.c b/gcc/testsuite/gcc.dg/vect/pr125509.c
new file mode 100644
index 0000000000000000000000000000000000000000..b5c479fc01a60d5dc8e8bd5cf0f65abddda5128d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr125509.c
@@ -0,0 +1,31 @@ 
+/* { dg-add-options vect_early_break } */
+/* { dg-do compile } */
+/* { dg-require-effective-target vect_early_break } */
+/* { dg-require-effective-target vect_int } */
+
+struct a {
+  char *b;
+  long c;
+} e;
+long d;
+char f;
+static bool g(char *h, long j) {
+  auto i = h + j - 1;
+  for (; h != i; h++)
+    if (*h)
+      return false;
+  return f;
+}
+void k();
+static void l(struct a h) {
+  if (!g(h.b, h.c))
+    if (d)
+      k();
+}
+void m() {
+  if (e.c != 1)
+    l(e);
+}
+
+/* { dg-final { scan-tree-dump "LOOP VECTORIZED" "vect" } } */
+/* { dg-final { scan-tree-dump "early break does not require epilog" "vect" } } */
diff --git a/gcc/tree-vect-loop-manip.cc b/gcc/tree-vect-loop-manip.cc
index a6d58d6798cda34ab7cd6657f1b2e5b9362af395..9c13a14d3533fd2f8c1e4918b22370f63c2d0eb4 100644
--- a/gcc/tree-vect-loop-manip.cc
+++ b/gcc/tree-vect-loop-manip.cc
@@ -3506,12 +3506,11 @@  vect_do_peeling (loop_vec_info loop_vinfo, tree niters, tree nitersm1,
       /* Peel prolog and put it on preheader edge of loop.  */
       edge scalar_e = LOOP_VINFO_SCALAR_MAIN_EXIT (loop_vinfo);
       edge prolog_e = NULL;
-      bool early_break_peel_p = LOOP_VINFO_EARLY_BRK_NEEDS_EPILOG (loop_vinfo);
       prolog = slpeel_tree_duplicate_loop_to_edge_cfg (loop, exit_e,
 						       scalar_loop, scalar_e,
 						       e, &prolog_e, true, NULL,
 						       uncounted_p, uncounted_p,
-						       early_break_peel_p);
+						       false);
 
       gcc_assert (prolog);
       prolog->force_vectorize = false;
@@ -3678,7 +3677,6 @@  vect_do_peeling (loop_vec_info loop_vinfo, tree niters, tree nitersm1,
 	  /* Handle any remaining dominator updates needed after
 	     inserting the loop skip edge above.  */
 	  if (LOOP_VINFO_EARLY_BREAKS (loop_vinfo)
-	      && LOOP_VINFO_EARLY_BRK_NEEDS_EPILOG (loop_vinfo)
 	      && prolog_peeling)
 	    {
 	      /* Adding a skip edge to skip a loop with multiple exits