[gcc(refs/users/aoliva/heads/testme)] -finline-stringops: avoid too-wide smallest_int_mode_for_size [PR112784]

[Alexandre Oliva]

https://gcc.gnu.org/g:98d208cbe6be1d5bbf2d20189dde46df982a6c97

commit 98d208cbe6be1d5bbf2d20189dde46df982a6c97
Author: Alexandre Oliva <oliva@adacore.com>
Date:   Fri Dec 8 21:41:56 2023 -0300

    -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:
---
 gcc/expr.cc                                        | 22 +++++++++++++---------
 .../i386/avx512cd-inline-stringops-pr112784.c      | 12 ++++++++++++
 2 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/gcc/expr.cc b/gcc/expr.cc
index 6da51f2aca2..178b3ec6d5a 100644
--- a/gcc/expr.cc
+++ b/gcc/expr.cc
@@ -2449,15 +2449,17 @@ 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 ()
+      || (GET_MODE_BITSIZE (as_a <scalar_int_mode> (int_move_mode))
+	  != incr * BITS_PER_UNIT))
     {
       move_mode = BLKmode;
       gcc_checking_assert (can_move_by_pieces (incr, align));
     }
   else
-    move_mode = int_move_mode;
+    move_mode = as_a <scalar_int_mode> (int_move_mode);
 
   x_addr = force_operand (XEXP (x, 0), NULL_RTX);
   y_addr = force_operand (XEXP (y, 0), NULL_RTX);
@@ -2701,16 +2703,18 @@ 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 ()
+      || (GET_MODE_BITSIZE (as_a <scalar_int_mode> (int_cmp_mode))
+	  != incr * BITS_PER_UNIT)
+      || !can_compare_p (NE, as_a <scalar_int_mode> (int_cmp_mode), ccp_jump))
     {
       cmp_mode = BLKmode;
       gcc_checking_assert (incr != 1);
     }
   else
-    cmp_mode = int_cmp_mode;
+    cmp_mode = as_a <scalar_int_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 00000000000..c81f99c693c
--- /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));
+}