[gcc r14-1610] RA: Constrain class of pic offset table pseudo to general regs

[Vladimir Makarov <vmakarov@gcc.gnu.org>]

https://gcc.gnu.org/g:8cc8707446b77f9413654b31704f5a639673c916

commit r14-1610-g8cc8707446b77f9413654b31704f5a639673c916
Author: Vladimir N. Makarov <vmakarov@redhat.com>
Date:   Wed Jun 7 09:51:54 2023 -0400

    RA: Constrain class of pic offset table pseudo to general regs
    
    On some targets an integer pseudo can be assigned to a FP reg.  For
    pic offset table pseudo it means we will reload the pseudo in this
    case and, as a consequence, memory containing the pseudo might be
    recognized as wrong one.  The patch fix this problem.
    
            PR target/109541
    
    gcc/ChangeLog:
    
            * ira-costs.cc: (find_costs_and_classes): Constrain classes of pic
            offset table pseudo to a general reg subset.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.target/sparc/pr109541.c: New.

Diff:
---
 gcc/ira-costs.cc                          | 10 ++++++++++
 gcc/testsuite/gcc.target/sparc/pr109541.c | 23 +++++++++++++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/gcc/ira-costs.cc b/gcc/ira-costs.cc
index ae8304ff938..d9e700e8947 100644
--- a/gcc/ira-costs.cc
+++ b/gcc/ira-costs.cc
@@ -2016,6 +2016,16 @@ find_costs_and_classes (FILE *dump_file)
 	      ira_assert (regno_aclass[i] != NO_REGS
 			  && ira_reg_allocno_class_p[regno_aclass[i]]);
 	    }
+	  if (pic_offset_table_rtx != NULL
+	      && i == (int) REGNO (pic_offset_table_rtx))
+	    {
+	      /* For some targets, integer pseudos can be assigned to fp
+		 regs.  As we don't want reload pic offset table pseudo, we
+		 should avoid using non-integer regs.  */
+	      regno_aclass[i]
+		= ira_reg_class_intersect[regno_aclass[i]][GENERAL_REGS];
+	      alt_class = ira_reg_class_intersect[alt_class][GENERAL_REGS];
+	    }
 	  if ((new_class
 	       = (reg_class) (targetm.ira_change_pseudo_allocno_class
 			      (i, regno_aclass[i], best))) != regno_aclass[i])
diff --git a/gcc/testsuite/gcc.target/sparc/pr109541.c b/gcc/testsuite/gcc.target/sparc/pr109541.c
new file mode 100644
index 00000000000..1360f101930
--- /dev/null
+++ b/gcc/testsuite/gcc.target/sparc/pr109541.c
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -mcpu=niagara4 -fpic -w" } */
+
+int rhash_sha512_process_block_A, rhash_sha512_process_block_i,
+rhash_sha512_process_block_block, rhash_sha512_process_block_W_0;
+
+unsigned rhash_sha512_process_block_W_2;
+
+void rhash_sha512_process_block (void)
+{
+  unsigned C, E, F, G, H, W_0, W_4, W_9, W_5, W_3, T1;
+
+  for (; rhash_sha512_process_block_i; rhash_sha512_process_block_i += 6) {
+    T1 = F + (rhash_sha512_process_block_W_2 += 6);
+    rhash_sha512_process_block_A += H & G + (W_5 += rhash_sha512_process_block_W_0);
+    H = C & T1 & E ^ F + (W_9 += rhash_sha512_process_block_W_0);
+    G = T1 ^ 6 + (W_0 += rhash_sha512_process_block_block);
+    F = (unsigned) &G;
+    T1 = (unsigned) (&T1 + (W_3 += rhash_sha512_process_block_block > 9 > W_4));
+    C = (unsigned) (T1 + &E);
+    W_4 += W_5 += rhash_sha512_process_block_W_0;
+  }
+}