[gcc r13-1920] PR target/106481: Handle CONST_WIDE_INT in REG_EQUAL during STV on x86_64.

[Roger Sayle <sayle@gcc.gnu.org>]

https://gcc.gnu.org/g:96e5f6696a1fa90493c464884984e9f1de86d817

commit r13-1920-g96e5f6696a1fa90493c464884984e9f1de86d817
Author: Roger Sayle <roger@nextmovesoftware.com>
Date:   Mon Aug 1 23:08:23 2022 +0100

    PR target/106481: Handle CONST_WIDE_INT in REG_EQUAL during STV on x86_64.
    
    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)))
    
    2022-08-01  Roger Sayle  <roger@nextmovesoftware.com>
                Uroš Bizjak  <ubizjak@gmail.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.

Diff:
---
 gcc/config/i386/i386-features.cc         | 11 +++++++++--
 gcc/testsuite/gcc.target/i386/pr106481.c | 17 +++++++++++++++++
 2 files changed, 26 insertions(+), 2 deletions(-)

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:
diff --git a/gcc/testsuite/gcc.target/i386/pr106481.c b/gcc/testsuite/gcc.target/i386/pr106481.c
new file mode 100644
index 00000000000..8cc704865cd
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr106481.c
@@ -0,0 +1,17 @@
+/* { dg-do compile { target int128 } } */
+/* { dg-options "-O2 -fno-dce -fno-forward-propagate -fno-rerun-cse-after-loop -Wno-psabi" } */
+
+typedef int V __attribute__((vector_size (64)));
+typedef __int128 W __attribute__((vector_size (64)));
+
+W w;
+V bar (void);
+
+void
+foo (V v, W)
+{
+  foo ((V){4, ~0}, (W) v);
+  foo (v, w);
+  bar ();
+}
+