[gcc(refs/users/marxin/heads/loop-unswitching-switch-v3)] Revert "Revert "Get rid of all float-int special cases in validate_subreg.""

[Martin Liska <marxin@gcc.gnu.org>]

https://gcc.gnu.org/g:2a171a5cace95acb085953f153da5b1be9a673aa

commit 2a171a5cace95acb085953f153da5b1be9a673aa
Author: Martin Liska <mliska@suse.cz>
Date:   Mon Sep 13 14:59:19 2021 +0200

    Revert "Revert "Get rid of all float-int special cases in validate_subreg.""
    
    This reverts commit 57b7c432cce893e1ba60d9b94a9606df6b419379.

Diff:
---
 gcc/emit-rtl.c | 40 ----------------------------------------
 1 file changed, 40 deletions(-)

diff --git a/gcc/emit-rtl.c b/gcc/emit-rtl.c
index e6158f243c0..0ba110879aa 100644
--- a/gcc/emit-rtl.c
+++ b/gcc/emit-rtl.c
@@ -922,46 +922,6 @@ validate_subreg (machine_mode omode, machine_mode imode,
 
   poly_uint64 regsize = REGMODE_NATURAL_SIZE (imode);
 
-  /* ??? This should not be here.  Temporarily continue to allow word_mode
-     subregs of anything.  The most common offender is (subreg:SI (reg:DF)).
-     Generally, backends are doing something sketchy but it'll take time to
-     fix them all.  */
-  if (omode == word_mode)
-    ;
-  /* ??? Similarly, e.g. with (subreg:DF (reg:TI)).  Though store_bit_field
-     is the culprit here, and not the backends.  */
-  else if (known_ge (osize, regsize) && known_ge (isize, osize))
-    ;
-  /* Allow component subregs of complex and vector.  Though given the below
-     extraction rules, it's not always clear what that means.  */
-  else if ((COMPLEX_MODE_P (imode) || VECTOR_MODE_P (imode))
-	   && GET_MODE_INNER (imode) == omode)
-    ;
-  /* ??? x86 sse code makes heavy use of *paradoxical* vector subregs,
-     i.e. (subreg:V4SF (reg:SF) 0) or (subreg:V4SF (reg:V2SF) 0).  This
-     surely isn't the cleanest way to represent this.  It's questionable
-     if this ought to be represented at all -- why can't this all be hidden
-     in post-reload splitters that make arbitrarily mode changes to the
-     registers themselves.  */
-  else if (VECTOR_MODE_P (omode)
-	   && GET_MODE_INNER (omode) == GET_MODE_INNER (imode))
-    ;
-  /* Subregs involving floating point modes are not allowed to
-     change size.  Therefore (subreg:DI (reg:DF) 0) is fine, but
-     (subreg:SI (reg:DF) 0) isn't.  */
-  else if (FLOAT_MODE_P (imode) || FLOAT_MODE_P (omode))
-    {
-      if (! (known_eq (isize, osize)
-	     /* LRA can use subreg to store a floating point value in
-		an integer mode.  Although the floating point and the
-		integer modes need the same number of hard registers,
-		the size of floating point mode can be less than the
-		integer mode.  LRA also uses subregs for a register
-		should be used in different mode in on insn.  */
-	     || lra_in_progress))
-	return false;
-    }
-
   /* Paradoxical subregs must have offset zero.  */
   if (maybe_gt (osize, isize))
     return known_eq (offset, 0U);