Re: [x86_64 PATCH] PR target/106481: Handle CONST_WIDE_INT in REG_EQUAL during STV.

[Uros Bizjak <ubizjak@gmail.com>]

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On Mon, Aug 1, 2022 at 3:43 PM Roger Sayle <roger@nextmovesoftware.com> wrote:
>
>
> This patch resolves PR target/106481, and is an oversight in my recent
> battles with REG_EQUAL notes during TImode STV (see PR target/106278
> https://gcc.gnu.org/pipermail/gcc-patches/2022-July/598416.html).
>
> The patch above's/current behaviour is that we check that the mode of
> the REG_EQUAL note is TImode before using PUT_MODE to set it to V1TImode.
> However, the new test case reveals that this doesn't consider REG_EQUAL
> notes that are CONST_INT or CONST_WIDE_INT, i.e. that are VOIDmode,
> and so STV produces:
>
> (insn 85 84 86 2 (set (reg:V1TI 113)
>         (reg:V1TI 84)) "pr106481.c":13:3 1766 {movv1ti_internal}
>      (expr_list:REG_EQUAL (const_wide_int 0x0ffffffff00000004)
>         (nil)))
>
> which causes problems as the const_wide_int isn't a valid immediate
> constant for V1TImode.  With this patch, we now generate the correct:
>
> (insn 85 84 86 2 (set (reg:V1TI 113)
>         (reg:V1TI 84)) "pr106481.c":13:3 1766 {movv1ti_internal}
>      (expr_list:REG_EQUAL (const_vector:V1TI [
>                 (const_wide_int 0x0ffffffff00000004)
>             ])
>         (nil)))
>
>
> This patch has been tested on x86_64-pc-linux-gnu with make bootstrap
> and make -k check, both with and without --target_board=unix{-m32},
> with no new failures.  Ok for mainline?
>
>
> 2022-08-01  Roger Sayle  <roger@nextmovesoftware.com>
>
> gcc/ChangeLog
>         PR target/106481
>         * config/i386/i386-features.cc (timode_scalar_chain::convert_insn):
>         Convert a CONST_SCALAR_INT_P in a REG_EQUAL note into a V1TImode
>         CONST_VECTOR.
>
> gcc/testsuite/ChangeLog
>         PR target/106481
>         * gcc.target/i386/pr106481.c: New test case.

OK, but how about we restructure the conditions a bit, like in the
attached patch?

Uros.

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diff --git a/gcc/config/i386/i386-features.cc b/gcc/config/i386/i386-features.cc
index e4cc4a30590..e3ecc22580a 100644
--- a/gcc/config/i386/i386-features.cc
+++ b/gcc/config/i386/i386-features.cc
@@ -1353,8 +1353,15 @@ timode_scalar_chain::convert_insn (rtx_insn *insn)
       if (GET_MODE (dst) == V1TImode)
 	{
 	  tmp = find_reg_equal_equiv_note (insn);
-	  if (tmp && GET_MODE (XEXP (tmp, 0)) == TImode)
-	    PUT_MODE (XEXP (tmp, 0), V1TImode);
+	  if (tmp)
+	    {
+	      if (GET_MODE (XEXP (tmp, 0)) == TImode)
+		PUT_MODE (XEXP (tmp, 0), V1TImode);
+	      else if (CONST_SCALAR_INT_P (XEXP (tmp, 0)))
+		XEXP (tmp, 0)
+		  = gen_rtx_CONST_VECTOR (V1TImode,
+					  gen_rtvec (1, XEXP (tmp, 0)));
+	    }
 	}
       break;
     case MEM: