[PATCH V1] HIGH part of symbol ref is invalid for constant pool

[Jiufu Guo <guojiufu@linux.ibm.com>]

Hi,

In patch https://gcc.gnu.org/pipermail/gcc-patches/2022-July/597712.html,
test case was not added.  After more check, a testcase is added for it.

The high part of the symbol address is invalid for the constant pool.
In function rs6000_cannot_force_const_mem, we already return true for
"HIGH with UNSPEC" rtx.  Below are some examples also indicate the high
part of a symbol_ref:
(high:DI (const:DI (plus:DI (symbol_ref:DI ("xx") (const_int 12 [0xc])))))
(high:DI (symbol_ref:DI ("var_1")..)))

This patch updates rs6000_cannot_force_const_mem to return true for
rtx with HIGH code.

Bootstrapped and regtested on ppc64le and ppc64.
Is it ok for trunk?

BR,
Jeff(Jiufu)


gcc/ChangeLog:

	* config/rs6000/rs6000.cc (rs6000_cannot_force_const_mem):
	Return true for HIGH code rtx.

gcc/testsuite/ChangeLog:

	* gcc.target/powerpc/constpoolcheck.c: New test.

---
 gcc/config/rs6000/rs6000.cc                       |  7 +++++--
 gcc/testsuite/gcc.target/powerpc/constpoolcheck.c | 11 +++++++++++
 2 files changed, 16 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/powerpc/constpoolcheck.c

diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
index 0af2085adc0..d56832ebbfc 100644
--- a/gcc/config/rs6000/rs6000.cc
+++ b/gcc/config/rs6000/rs6000.cc
@@ -9704,8 +9704,11 @@ 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)
+  /* High part of a symbol ref/address can not be put into constant pool. e.g.
+     (high:DI (symbol_ref:DI ("var")..)) or
+     (high:DI (unspec:DI [(symbol_ref/u:DI ("*.LC0")..)
+     (high:DI (const:DI (plus:DI (symbol_ref:DI ("xx")) (const_int 12)))).  */
+  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/constpoolcheck.c b/gcc/testsuite/gcc.target/powerpc/constpoolcheck.c
new file mode 100644
index 00000000000..ed7a994827b
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/constpoolcheck.c
@@ -0,0 +1,11 @@
+/* { dg-do compile { target powerpc*-*-* } } */
+/* { 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;
+}
+
-- 
2.17.1