[PATCH] xtensa: Revise 89afb2e86fcb29c559b2957fdcbea0d01740c49b

[PATCH] xtensa: Revise 89afb2e86fcb29c559b2957fdcbea0d01740c49b

[Takayuki 'January June' Suwa]

In the previously posted patch
"xtensa: Make complex hard register clobber elimination more robust and accurate",
the check code for insns that refer to the [DS]Cmode hard register before
it is overwritten after it is clobbered is incomplete.  Fortunately such
insns are seldom emitted, so it didn't matter.

This patch fixes that for the sake of completeness.

gcc/ChangeLog:

	* config/xtensa/xtensa.md:
	Fix exit from loops detecting references before overwriting in the
	split pattern.
---
 gcc/config/xtensa/xtensa.md | 72 +++++++++++++++++++------------------
 1 file changed, 37 insertions(+), 35 deletions(-)

diff --git a/gcc/config/xtensa/xtensa.md b/gcc/config/xtensa/xtensa.md
index 8432d7bcb..e26772413 100644
--- a/gcc/config/xtensa/xtensa.md
+++ b/gcc/config/xtensa/xtensa.md
@@ -2976,45 +2976,47 @@
 {
   auto_sbitmap bmp (FIRST_PSEUDO_REGISTER);
   rtx_insn *insn;
-  rtx reg = gen_rtx_REG (SImode, 0);
+  rtx reg = gen_rtx_REG (SImode, 0), dest;
+  unsigned int regno;
+  sbitmap_iterator iter;
   bitmap_set_range (bmp, REGNO (operands[0]), REG_NREGS (operands[0]));
   for (insn = next_nonnote_nondebug_insn_bb (curr_insn);
        insn; insn = next_nonnote_nondebug_insn_bb (insn))
-    {
-      sbitmap_iterator iter;
-      unsigned int regno;
-      if (NONJUMP_INSN_P (insn))
-	{
-	  EXECUTE_IF_SET_IN_BITMAP (bmp, 2, regno, iter)
-	    {
-	      set_regno_raw (reg, regno, REG_NREGS (reg));
-	      if (reg_overlap_mentioned_p (reg, PATTERN (insn)))
-		break;
-	    }
-	  if (GET_CODE (PATTERN (insn)) == SET)
-	    {
-	      rtx x = SET_DEST (PATTERN (insn));
-	      if (REG_P (x) && HARD_REGISTER_P (x))
-		bitmap_clear_range (bmp, REGNO (x), REG_NREGS (x));
-	      else if (SUBREG_P (x) && HARD_REGISTER_P (SUBREG_REG (x)))
-		{
-		  struct subreg_info info;
-		  subreg_get_info (regno = REGNO (SUBREG_REG (x)),
-				   GET_MODE (SUBREG_REG (x)),
-				   SUBREG_BYTE (x), GET_MODE (x), &info);
-		  if (!info.representable_p)
-		    break;
-		  bitmap_clear_range (bmp, regno + info.offset, info.nregs);
-		}
-	    }
-	  if (bitmap_empty_p (bmp))
-	    goto FALLTHRU;
-	}
-      else if (CALL_P (insn))
+    if (NONJUMP_INSN_P (insn))
+      {
 	EXECUTE_IF_SET_IN_BITMAP (bmp, 2, regno, iter)
-	 if (call_used_or_fixed_reg_p (regno))
-	   break;
-    }
+	  {
+	    set_regno_raw (reg, regno, REG_NREGS (reg));
+	    if (reg_referenced_p (reg, PATTERN (insn)))
+	      goto ABORT;
+	  }
+	if (GET_CODE (PATTERN (insn)) == SET
+	    || GET_CODE (PATTERN (insn)) == CLOBBER)
+	  {
+	    dest = SET_DEST (PATTERN (insn));
+	    if (REG_P (dest) && HARD_REGISTER_P (dest))
+	      bitmap_clear_range (bmp, REGNO (dest), REG_NREGS (dest));
+	    else if (SUBREG_P (dest)
+		     && HARD_REGISTER_P (SUBREG_REG (dest)))
+	      {
+		struct subreg_info info;
+		subreg_get_info (regno = REGNO (SUBREG_REG (dest)),
+				 GET_MODE (SUBREG_REG (dest)),
+				 SUBREG_BYTE (dest), GET_MODE (dest),
+				 &info);
+		if (!info.representable_p)
+		  break;
+		bitmap_clear_range (bmp, regno + info.offset, info.nregs);
+	      }
+	  }
+	if (bitmap_empty_p (bmp))
+	  goto FALLTHRU;
+      }
+    else if (CALL_P (insn))
+      EXECUTE_IF_SET_IN_BITMAP (bmp, 2, regno, iter)
+	if (call_used_or_fixed_reg_p (regno))
+	  goto ABORT;
+ABORT:
   FAIL;
 FALLTHRU:;
 })
-- 
2.30.2

Re: [PATCH] xtensa: Revise 89afb2e86fcb29c559b2957fdcbea0d01740c49b

[Max Filippov]

On Thu, Jan 19, 2023 at 7:33 PM Takayuki 'January June' Suwa
<jjsuwa_sys3175@yahoo.co.jp> wrote:
>
> In the previously posted patch
> "xtensa: Make complex hard register clobber elimination more robust and accurate",
> the check code for insns that refer to the [DS]Cmode hard register before
> it is overwritten after it is clobbered is incomplete.  Fortunately such
> insns are seldom emitted, so it didn't matter.
>
> This patch fixes that for the sake of completeness.
>
> gcc/ChangeLog:
>
>         * config/xtensa/xtensa.md:
>         Fix exit from loops detecting references before overwriting in the
>         split pattern.
> ---
>  gcc/config/xtensa/xtensa.md | 72 +++++++++++++++++++------------------
>  1 file changed, 37 insertions(+), 35 deletions(-)

Regtested for target=xtensa-linux-uclibc, no new regressions.
Committed to master with more human readable subject line.

-- 
Thanks.
-- Max