[gcc r13-3499] rs6000: cannot_force_const_mem for HIGH code rtx[PR106460]

[Jiu Fu Guo <guojiufu@gcc.gnu.org>]

https://gcc.gnu.org/g:978ec4825c2e5cb0ec03d857ea038440d566ff42

commit r13-3499-g978ec4825c2e5cb0ec03d857ea038440d566ff42
Author: Jiufu Guo <guojiufu@linux.ibm.com>
Date:   Tue Jul 19 18:30:58 2022 +0800

    rs6000: cannot_force_const_mem for HIGH code rtx[PR106460]
    
    As the issue in PR106460, a rtx 'high:DI (symbol_ref:DI ("var_48")' is tried
    to store into constant pool and ICE occur.  But actually, this rtx represents
    partial incomplete address and can not be put into a .rodata section.
    
    This patch updates rs6000_cannot_force_const_mem to return true for rtx(s) with
    HIGH code, because these rtx(s) indicate part of address and are not ok for
    constant pool.
    
    Below are some examples:
    (high:DI (const:DI (plus:DI (symbol_ref:DI ("xx") (const_int 12 [0xc])))))
    (high:DI (symbol_ref:DI ("var_1")..)))
    
            PR target/106460
    
    gcc/ChangeLog:
    
            * config/rs6000/rs6000.cc (rs6000_cannot_force_const_mem): Return true
            for HIGH code rtx.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.target/powerpc/pr106460.c: New test.

Diff:
---
 gcc/config/rs6000/rs6000.cc                 |  7 +++++--
 gcc/testsuite/gcc.target/powerpc/pr106460.c | 12 ++++++++++++
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
index 01e5bbcf0b6..a85d7630b41 100644
--- a/gcc/config/rs6000/rs6000.cc
+++ b/gcc/config/rs6000/rs6000.cc
@@ -9759,8 +9759,11 @@ rs6000_init_stack_protect_guard (void)
 static bool
 rs6000_cannot_force_const_mem (machine_mode mode ATTRIBUTE_UNUSED, rtx x)
 {
-  if (GET_CODE (x) == HIGH
-      && GET_CODE (XEXP (x, 0)) == UNSPEC)
+  /* If GET_CODE (x) is HIGH, the 'X' represets the high part of a symbol_ref.
+     It can not be put into a constant pool.  e.g.
+     (high:DI (unspec:DI [(symbol_ref/u:DI ("*.LC0")..)
+     (high:DI (symbol_ref:DI ("var")..)).  */
+  if (GET_CODE (x) == HIGH)
     return true;
 
   /* A TLS symbol in the TOC cannot contain a sum.  */
diff --git a/gcc/testsuite/gcc.target/powerpc/pr106460.c b/gcc/testsuite/gcc.target/powerpc/pr106460.c
new file mode 100644
index 00000000000..aae4b015bba
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pr106460.c
@@ -0,0 +1,12 @@
+/* { dg-require-effective-target power10_ok } */
+/* { dg-options "-O1 -mdejagnu-cpu=power10" } */
+
+/* (high:DI (symbol_ref:DI ("var_48")..))) should not cause ICE. */
+extern short var_48;
+void
+foo (double *r)
+{
+  if (var_48)
+    *r = 1234.5678;
+}
+