diff mbox series

loop-invariant: Split preheader edge if the preheader bb ends with jump [PR106751]

Message ID Y5w2HuVCI8qOxaTP@tucnak
State Unresolved
Headers
Series loop-invariant: Split preheader edge if the preheader bb ends with jump [PR106751] |

Checks

Context Check Description
snail/gcc-patch-check warning Git am fail log

Commit Message

Jakub Jelinek Dec. 16, 2022, 9:10 a.m. UTC 
  Hi!

The RTL loop passes only request simple preheaders, but don't require
fallthru preheaders, while move_invariant_reg apparently assumes the
latter, that it can just append instruction(s) to the end of the preheader
basic block.

The following patch fixes that by splitting the preheader edge if
the preheader bb ends with a JUMP_INSN (asm goto in this case).
Without that we get control flow in the middle of a bb.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2022-12-16  Jakub Jelinek  <jakub@redhat.com>

	PR rtl-optimization/106751
	* loop-invariant.cc (move_invariant_reg): If preheader bb ends
	with a JUMP_INSN, split the preheader edge and emit invariants
	into the new preheader basic block.

	* gcc.c-torture/compile/pr106751.c: New test.


	Jakub

Comments

Richard Biener Dec. 16, 2022, 9:12 a.m. UTC | #1 
On Fri, 16 Dec 2022, Jakub Jelinek wrote:

> Hi!
> 
> The RTL loop passes only request simple preheaders, but don't require
> fallthru preheaders, while move_invariant_reg apparently assumes the
> latter, that it can just append instruction(s) to the end of the preheader
> basic block.
> 
> The following patch fixes that by splitting the preheader edge if
> the preheader bb ends with a JUMP_INSN (asm goto in this case).
> Without that we get control flow in the middle of a bb.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

OK.

> 2022-12-16  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR rtl-optimization/106751
> 	* loop-invariant.cc (move_invariant_reg): If preheader bb ends
> 	with a JUMP_INSN, split the preheader edge and emit invariants
> 	into the new preheader basic block.
> 
> 	* gcc.c-torture/compile/pr106751.c: New test.
> 
> --- gcc/loop-invariant.cc.jj	2022-01-18 11:58:59.683980614 +0100
> +++ gcc/loop-invariant.cc	2022-12-15 17:14:32.906883258 +0100
> @@ -1837,6 +1837,8 @@ move_invariant_reg (class loop *loop, un
>        else if (dump_file)
>  	fprintf (dump_file, "Invariant %d moved without introducing a new "
>  			    "temporary register\n", invno);
> +      if (JUMP_P (BB_END (preheader)))
> +	preheader = split_edge (loop_preheader_edge (loop));
>        reorder_insns (inv->insn, inv->insn, BB_END (preheader));
>        df_recompute_luids (preheader);
>  
> --- gcc/testsuite/gcc.c-torture/compile/pr106751.c.jj	2022-12-15 17:44:35.602519711 +0100
> +++ gcc/testsuite/gcc.c-torture/compile/pr106751.c	2022-12-15 17:44:21.789721827 +0100
> @@ -0,0 +1,17 @@
> +/* PR rtl-optimization/106751 */
> +
> +int *foo (void);
> +
> +void
> +bar (void)
> +{
> +  asm goto ("" : : : : lab);
> +  __builtin_unreachable ();
> +lab:
> +  while (1)
> +    {
> +      int o;
> +      asm ("" : "=r" (o) : "g" (1));
> +      *foo () = o;
> +    }
> +}
> 
> 	Jakub
> 
>
diff mbox series

Patch

--- gcc/loop-invariant.cc.jj	2022-01-18 11:58:59.683980614 +0100
+++ gcc/loop-invariant.cc	2022-12-15 17:14:32.906883258 +0100
@@ -1837,6 +1837,8 @@  move_invariant_reg (class loop *loop, un
       else if (dump_file)
 	fprintf (dump_file, "Invariant %d moved without introducing a new "
 			    "temporary register\n", invno);
+      if (JUMP_P (BB_END (preheader)))
+	preheader = split_edge (loop_preheader_edge (loop));
       reorder_insns (inv->insn, inv->insn, BB_END (preheader));
       df_recompute_luids (preheader);
 
--- gcc/testsuite/gcc.c-torture/compile/pr106751.c.jj	2022-12-15 17:44:35.602519711 +0100
+++ gcc/testsuite/gcc.c-torture/compile/pr106751.c	2022-12-15 17:44:21.789721827 +0100
@@ -0,0 +1,17 @@ 
+/* PR rtl-optimization/106751 */
+
+int *foo (void);
+
+void
+bar (void)
+{
+  asm goto ("" : : : : lab);
+  __builtin_unreachable ();
+lab:
+  while (1)
+    {
+      int o;
+      asm ("" : "=r" (o) : "g" (1));
+      *foo () = o;
+    }
+}