diff mbox series

[1/8] Make force_subreg emit nothing on failure

Message ID 20240617095336.871176-2-richard.sandiford@arm.com
State New
Headers show
Series [1/8] Make force_subreg emit nothing on failure | expand

Commit Message

Richard Sandiford June 17, 2024, 9:53 a.m. UTC 
While adding more uses of force_subreg, I realised that it should
be more careful to emit no instructions on failure.  This kind of
failure should be very rare, so I don't think it's a case worth
optimising for.

gcc/
	* explow.cc (force_subreg): Emit no instructions on failure.
---
 gcc/explow.cc | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/gcc/explow.cc b/gcc/explow.cc
index f6843398c4b..bd93c878064 100644
--- a/gcc/explow.cc
+++ b/gcc/explow.cc
@@ -756,8 +756,12 @@  force_subreg (machine_mode outermode, rtx op,
   if (x)
     return x;
 
+  auto *start = get_last_insn ();
   op = copy_to_mode_reg (innermode, op);
-  return simplify_gen_subreg (outermode, op, innermode, byte);
+  rtx res = simplify_gen_subreg (outermode, op, innermode, byte);
+  if (!res)
+    delete_insns_since (start);
+  return res;
 }
 
 /* If X is a memory ref, copy its contents to a new temp reg and return