From: Alexandre Oliva <oliva@adacore.com>
Date: Mon, 11 Dec 2023 18:09:28 +0000 (-0300)
Subject: -finline-stringops: avoid too-wide smallest_int_mode_for_size [PR112784]
X-Git-Tag: basepoints/gcc-15~3708
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=a8a3d832e609501002dee54150abfd96a28fe532;p=thirdparty%2Fgcc.git

-finline-stringops: avoid too-wide smallest_int_mode_for_size [PR112784]

smallest_int_mode_for_size may abort when the requested mode is not
available.  Call int_mode_for_size instead, that signals the
unsatisfiable request in a more graceful way.


for  gcc/ChangeLog

	PR middle-end/112784
	* expr.cc (emit_block_move_via_loop): Call int_mode_for_size
	for maybe-too-wide sizes.
	(emit_block_cmp_via_loop): Likewise.

for  gcc/testsuite/ChangeLog

	PR middle-end/112784
	* gcc.target/i386/avx512cd-inline-stringops-pr112784.c: New.
---

diff --git a/gcc/expr.cc b/gcc/expr.cc
index 4686cacd22fe..9fef2bf65853 100644
--- a/gcc/expr.cc
+++ b/gcc/expr.cc
@@ -2449,15 +2449,14 @@ emit_block_move_via_loop (rtx x, rtx y, rtx size,
     }
   emit_move_insn (iter, iter_init);
 
-  scalar_int_mode int_move_mode
-    = smallest_int_mode_for_size (incr * BITS_PER_UNIT);
-  if (GET_MODE_BITSIZE (int_move_mode) != incr * BITS_PER_UNIT)
+  opt_scalar_int_mode int_move_mode
+    = int_mode_for_size (incr * BITS_PER_UNIT, 1);
+  if (!int_move_mode.exists (&move_mode)
+      || GET_MODE_BITSIZE (int_move_mode.require ()) != incr * BITS_PER_UNIT)
     {
       move_mode = BLKmode;
       gcc_checking_assert (can_move_by_pieces (incr, align));
     }
-  else
-    move_mode = int_move_mode;
 
   x_addr = force_operand (XEXP (x, 0), NULL_RTX);
   y_addr = force_operand (XEXP (y, 0), NULL_RTX);
@@ -2701,16 +2700,15 @@ emit_block_cmp_via_loop (rtx x, rtx y, rtx len, tree len_type, rtx target,
   iter = gen_reg_rtx (iter_mode);
   emit_move_insn (iter, iter_init);
 
-  scalar_int_mode int_cmp_mode
-    = smallest_int_mode_for_size (incr * BITS_PER_UNIT);
-  if (GET_MODE_BITSIZE (int_cmp_mode) != incr * BITS_PER_UNIT
-      || !can_compare_p (NE, int_cmp_mode, ccp_jump))
+  opt_scalar_int_mode int_cmp_mode
+    = int_mode_for_size (incr * BITS_PER_UNIT, 1);
+  if (!int_cmp_mode.exists (&cmp_mode)
+      || GET_MODE_BITSIZE (int_cmp_mode.require ()) != incr * BITS_PER_UNIT
+      || !can_compare_p (NE, cmp_mode, ccp_jump))
     {
       cmp_mode = BLKmode;
       gcc_checking_assert (incr != 1);
     }
-  else
-    cmp_mode = int_cmp_mode;
 
   /* Save the base addresses.  */
   x_addr = force_operand (XEXP (x, 0), NULL_RTX);
diff --git a/gcc/testsuite/gcc.target/i386/avx512cd-inline-stringops-pr112784.c b/gcc/testsuite/gcc.target/i386/avx512cd-inline-stringops-pr112784.c
new file mode 100644
index 000000000000..c81f99c693c2
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/avx512cd-inline-stringops-pr112784.c
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+/* { dg-options "-mavx512cd -finline-stringops" } */
+
+struct S {
+  int e;
+} __attribute__((aligned(128)));
+
+int main() {
+  struct S s1;
+  struct S s2;
+  int v = __builtin_memcmp(&s1, &s2, sizeof(s1));
+}