From: Hans-Peter Nilsson <hp@axis.com>
Date: Sat, 23 Dec 2023 23:10:32 +0000 (+0100)
Subject: CRIS: Fix PR middle-end/113109; "throw" failing
X-Git-Tag: basepoints/gcc-15~3322
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=3d03630b123411340e52d05124cb0cacfa1fc8b0;p=thirdparty%2Fgcc.git

CRIS: Fix PR middle-end/113109; "throw" failing

TL;DR: the "dse1" pass removed the eh-return-address store.  The
PA also marks its EH_RETURN_HANDLER_RTX as volatile, for the same
reason, as does visum.  See PR32769 - it's the same thing on PA.

Conceptually, it's logical that stores to incoming args are
optimized out on the return path or if no loads are seen -
at least before epilogue expansion, when the subsequent load
isn't seen in the RTL, as is the case for the "dse1" pass.

I haven't looked into why this problem, that appeared for the PA
already in 2007, was seen for CRIS only recently (with
r14-6674-g4759383245ac97).

	PR middle-end/113109
	* config/cris/cris.cc (cris_eh_return_handler_rtx): New function.
	* config/cris/cris-protos.h (cris_eh_return_handler_rtx): Prototype.
	* config/cris/cris.h (EH_RETURN_HANDLER_RTX): Redefine to call
	cris_eh_return_handler_rtx.
---

diff --git a/gcc/config/cris/cris-protos.h b/gcc/config/cris/cris-protos.h
index 666e04f9eeec..06678c723b56 100644
--- a/gcc/config/cris/cris-protos.h
+++ b/gcc/config/cris/cris-protos.h
@@ -28,6 +28,7 @@ extern bool cris_reload_address_legitimized (rtx, machine_mode, int, int, int);
 extern int cris_side_effect_mode_ok (enum rtx_code, rtx *, int, int,
                                      int, int, int);
 extern rtx cris_return_addr_rtx (int, rtx);
+extern rtx cris_eh_return_handler_rtx ();
 extern rtx cris_split_movdx (rtx *);
 extern bool cris_base_p (const_rtx, bool);
 extern bool cris_base_or_autoincr_p (const_rtx, bool);
diff --git a/gcc/config/cris/cris.cc b/gcc/config/cris/cris.cc
index 7705c25ed6c0..38a4dd29114d 100644
--- a/gcc/config/cris/cris.cc
+++ b/gcc/config/cris/cris.cc
@@ -1382,6 +1382,22 @@ cris_return_addr_rtx (int count, rtx frameaddr ATTRIBUTE_UNUSED)
     : NULL_RTX;
 }
 
+/* Setting the EH return return address is done by a *store* to a memory
+   address expressed as relative to "*incoming* args".  That store will
+   be optimized away, unless the MEM is marked as volatile.  N.B.: no
+   optimization opportunities are expected to be lost due to this hack;
+   __builtin_eh_return isn't called from elsewhere than the EH machinery
+   in libgcc.  */
+
+rtx
+cris_eh_return_handler_rtx ()
+{
+  rtx ret = cris_return_addr_rtx (0, NULL_RTX);
+  gcc_assert (MEM_P (ret));
+  MEM_VOLATILE_P (ret) = true;
+  return ret;
+}
+
 /* Accessor used in cris.md:return because cfun->machine isn't available
    there.  */
 
diff --git a/gcc/config/cris/cris.h b/gcc/config/cris/cris.h
index 087b226ee475..ced356088302 100644
--- a/gcc/config/cris/cris.h
+++ b/gcc/config/cris/cris.h
@@ -551,8 +551,7 @@ enum reg_class
 #define CRIS_STACKADJ_REG CRIS_STRUCT_VALUE_REGNUM
 #define EH_RETURN_STACKADJ_RTX gen_rtx_REG (SImode, CRIS_STACKADJ_REG)
 
-#define EH_RETURN_HANDLER_RTX \
-  cris_return_addr_rtx (0, NULL)
+#define EH_RETURN_HANDLER_RTX cris_eh_return_handler_rtx ()
 
 #define INIT_EXPANDERS cris_init_expanders ()