[gcc(refs/users/meissner/heads/work168-test)] Restrict modes that can got in SPRs.

[Michael Meissner]

https://gcc.gnu.org/g:2ef7f940f369356534008c21b3472856a6060d22

commit 2ef7f940f369356534008c21b3472856a6060d22
Author: Michael Meissner <meissner@linux.ibm.com>
Date:   Wed Jun 12 21:01:31 2024 -0400

    Restrict modes that can got in SPRs.
    
    2024-06-04  Michael Meissner  <meissner@linux.ibm.com>
    
    gcc/
    
            * config/rs6000/rs6000.cc (rs6000_hard_regno_mode_ok_uncached): Restrict
            the modes that can go in SPR registers.

Diff:
---
 gcc/config/rs6000/rs6000.cc | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
index c5c4191127e4..02be24b1a914 100644
--- a/gcc/config/rs6000/rs6000.cc
+++ b/gcc/config/rs6000/rs6000.cc
@@ -1851,9 +1851,13 @@ static int
 rs6000_hard_regno_mode_ok_uncached (int regno, machine_mode mode)
 {
   int last_regno = regno + rs6000_hard_regno_nregs[mode][regno] - 1;
+  bool orig_complex_p = false;
 
   if (COMPLEX_MODE_P (mode))
-    mode = GET_MODE_INNER (mode);
+    {
+      mode = GET_MODE_INNER (mode);
+      orig_complex_p = true;
+    }
 
   /* Vector pair modes need even/odd VSX register pairs.  Only allow vector
      registers.  */
@@ -1935,6 +1939,18 @@ rs6000_hard_regno_mode_ok_uncached (int regno, machine_mode mode)
   if (CA_REGNO_P (regno))
     return mode == Pmode || mode == SImode;
 
+  /* Do some consistancy checks for SPRs.  Don't allow complex modes.
+     VRSAVE/VSCR are always 32-bit SPRs.  Don't allow floating point modes in
+     the other SPRs.  Don't allow large modes that don't fit in a single
+     register. */
+  if (regno == VRSAVE_REGNO || regno == VSCR_REGNO)
+      return (!orig_complex_p && mode == SImode);
+
+  if (regno == LR_REGNO || regno == CTR_REGNO)
+    return (!orig_complex_p
+	    && GET_MODE_SIZE (mode) <= UNITS_PER_WORD
+	    && !SCALAR_FLOAT_MODE_P (mode));
+
   /* AltiVec only in AldyVec registers.  */
   if (ALTIVEC_REGNO_P (regno))
     return (VECTOR_MEM_ALTIVEC_OR_VSX_P (mode)