[gcc r14-1528] PR target/110083: Fix-up REG_EQUAL notes on COMPARE in STV.

[gcc r14-1528] PR target/110083: Fix-up REG_EQUAL notes on COMPARE in STV.

[Roger Sayle]

https://gcc.gnu.org/g:8ab9fb6b8e05cf9acca7bd8282979ede53524cf1

commit r14-1528-g8ab9fb6b8e05cf9acca7bd8282979ede53524cf1
Author: Roger Sayle <roger@nextmovesoftware.com>
Date:   Sun Jun 4 11:59:32 2023 +0100

    PR target/110083: Fix-up REG_EQUAL notes on COMPARE in STV.
    
    This patch fixes PR target/110083, an ICE-on-valid regression exposed by
    my recent PTEST improvements (to address PR target/109973).  The latent
    bug (admittedly mine) is that the scalar-to-vector (STV) pass doesn't update
    or delete REG_EQUAL notes attached to COMPARE instructions.  As a result
    the operands of COMPARE would be mismatched, with the register transformed
    to V1TImode, but the immediate operand left as const_wide_int, which is
    valid for TImode but not V1TImode.  This remained latent when the STV
    conversion converted the mode of the COMPARE to CCmode, with later passes
    recognizing the REG_EQUAL note is obviously invalid as the modes didn't
    match, but now that we (correctly) preserve the CCZmode on COMPARE, the
    mismatched operand modes trigger a sanity checking ICE downstream.
    
    Fixed by updating (or deleting) any REG_EQUAL notes in convert_compare.
    
    Before:
        (expr_list:REG_EQUAL (compare:CCZ (reg:V1TI 119 [ ivin.29_38 ])
            (const_wide_int 0x80000000000000000000000000000000))
    
    After:
        (expr_list:REG_EQUAL (compare:CCZ (reg:V1TI 119 [ ivin.29_38 ])
            (const_vector:V1TI [
                (const_wide_int 0x80000000000000000000000000000000)
             ]))
    
    2023-06-04  Roger Sayle  <roger@nextmovesoftware.com>
    
    gcc/ChangeLog
            PR target/110083
            * config/i386/i386-features.cc (scalar_chain::convert_compare):
            Update or delete REG_EQUAL notes, converting CONST_INT and
            CONST_WIDE_INT immediate operands to a suitable CONST_VECTOR.
    
    gcc/testsuite/ChangeLog
            PR target/110083
            * gcc.target/i386/pr110083.c: New test case.

Diff:
---
 gcc/config/i386/i386-features.cc         | 33 ++++++++++++++++++++++++++++++++
 gcc/testsuite/gcc.target/i386/pr110083.c | 26 +++++++++++++++++++++++++
 2 files changed, 59 insertions(+)

diff --git a/gcc/config/i386/i386-features.cc b/gcc/config/i386/i386-features.cc
index 3417f6bd0d1..4a3b07ae045 100644
--- a/gcc/config/i386/i386-features.cc
+++ b/gcc/config/i386/i386-features.cc
@@ -980,6 +980,39 @@ rtx
 scalar_chain::convert_compare (rtx op1, rtx op2, rtx_insn *insn)
 {
   rtx src, tmp;
+
+  /* Handle any REG_EQUAL notes.  */
+  tmp = find_reg_equal_equiv_note (insn);
+  if (tmp)
+    {
+      if (GET_CODE (XEXP (tmp, 0)) == COMPARE
+	  && GET_MODE (XEXP (tmp, 0)) == CCZmode
+	  && REG_P (XEXP (XEXP (tmp, 0), 0)))
+	{
+	  rtx *op = &XEXP (XEXP (tmp, 0), 1);
+	  if (CONST_SCALAR_INT_P (*op))
+	    {
+	      if (constm1_operand (*op, GET_MODE (*op)))
+		*op = CONSTM1_RTX (vmode);
+	      else
+		{
+		  unsigned n = GET_MODE_NUNITS (vmode);
+		  rtx *v = XALLOCAVEC (rtx, n);
+		  v[0] = *op;
+		  for (unsigned i = 1; i < n; ++i)
+		    v[i] = const0_rtx;
+		  *op = gen_rtx_CONST_VECTOR (vmode, gen_rtvec_v (n, v));
+		}
+	      tmp = NULL_RTX;
+	    }
+	  else if (REG_P (*op))
+	    tmp = NULL_RTX;
+	}
+
+      if (tmp)
+	remove_note (insn, tmp);
+    }
+
   /* Comparison against anything other than zero, requires an XOR.  */
   if (op2 != const0_rtx)
     {
diff --git a/gcc/testsuite/gcc.target/i386/pr110083.c b/gcc/testsuite/gcc.target/i386/pr110083.c
new file mode 100644
index 00000000000..4b38ca8b519
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr110083.c
@@ -0,0 +1,26 @@
+/* { dg-do compile { target int128 } } */
+/* { dg-options "-O2 -msse4 -mstv -mno-stackrealign" } */
+typedef int TItype __attribute__ ((mode (TI)));
+typedef unsigned int UTItype __attribute__ ((mode (TI)));
+
+void foo (void)
+{
+  static volatile TItype ivin, ivout;
+  static volatile float fv1, fv2;
+  ivin = ((TItype) (UTItype) ~ (((UTItype) ~ (UTItype) 0) >> 1));
+  fv1 = ((TItype) (UTItype) ~ (((UTItype) ~ (UTItype) 0) >> 1));
+  fv2 = ivin;
+  ivout = fv2;
+  if (ivin != ((TItype) (UTItype) ~ (((UTItype) ~ (UTItype) 0) >> 1))
+      || ((((128) > sizeof (TItype) * 8 - 1)) && ivout != ivin)
+      || ((((128) > sizeof (TItype) * 8 - 1))
+	  && ivout !=
+	  ((TItype) (UTItype) ~ (((UTItype) ~ (UTItype) 0) >> 1)))
+      || fv1 !=
+      (float) ((TItype) (UTItype) ~ (((UTItype) ~ (UTItype) 0) >> 1))
+      || fv2 !=
+      (float) ((TItype) (UTItype) ~ (((UTItype) ~ (UTItype) 0) >> 1))
+      || fv1 != fv2)
+    __builtin_abort ();
+}
+