[gcc(refs/vendors/ARM/heads/morello)] aarch64: -mtrack-speculation pass capability enablement

[Alex Coplan <acoplan@gcc.gnu.org>]

https://gcc.gnu.org/g:ce2e4f958b407ae0bb9a66c34a708c74ba15eb3f

commit ce2e4f958b407ae0bb9a66c34a708c74ba15eb3f
Author: Victor Do Nascimento <victor.donascimento@arm.com>
Date:   Mon Jan 16 17:09:32 2023 +0000

    aarch64: -mtrack-speculation pass capability enablement
    
    Fix the code sequence generated for speculative execution tracking so
    that it uses the proper capability-handling instructions, thus
    preventing the invalidation of the CSP stack pointer capability when
    the speculation tracking state is encoded into the stack pointer.
    
    For capability-enabled targets, we see the following change in the
    generated tracking code from:
    
        mov  tmp, sp
        and  tmp, tmp, tracker
        mov  SP, tmp
    
    to:
    
        mov  tmp, sp
        and  tmp, tmp, tracker
        scvalue  CSP, CSP, tmp

Diff:
---
 gcc/config/aarch64/aarch64-speculation.cc                    |  9 ++++++---
 .../gcc.target/aarch64/morello/mtrack-speculation.c          | 12 ++++++++++++
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/gcc/config/aarch64/aarch64-speculation.cc b/gcc/config/aarch64/aarch64-speculation.cc
index f490b64ae61..2453f62c96c 100644
--- a/gcc/config/aarch64/aarch64-speculation.cc
+++ b/gcc/config/aarch64/aarch64-speculation.cc
@@ -141,14 +141,17 @@
 static rtx_insn *
 aarch64_speculation_clobber_sp ()
 {
-  rtx sp = gen_rtx_REG (DImode, SP_REGNUM);
+  rtx sp = gen_rtx_REG (Pmode, SP_REGNUM);
   rtx tracker = gen_rtx_REG (DImode, SPECULATION_TRACKER_REGNUM);
   rtx scratch = gen_rtx_REG (DImode, SPECULATION_SCRATCH_REGNUM);
 
   start_sequence ();
-  emit_insn (gen_rtx_SET (scratch, sp));
+  emit_insn (gen_rtx_SET (scratch, drop_capability (sp)));
   emit_insn (gen_anddi3 (scratch, scratch, tracker));
-  emit_insn (gen_rtx_SET (sp, scratch));
+  if (CAPABILITY_MODE_P (Pmode))
+    emit_insn (gen_replace_address_value_cadi (sp, sp, scratch));
+  else
+    emit_insn (gen_rtx_SET (sp, scratch));
   rtx_insn *seq = get_insns ();
   end_sequence ();
   return seq;
diff --git a/gcc/testsuite/gcc.target/aarch64/morello/mtrack-speculation.c b/gcc/testsuite/gcc.target/aarch64/morello/mtrack-speculation.c
new file mode 100644
index 00000000000..ec7f3ba6a53
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/morello/mtrack-speculation.c
@@ -0,0 +1,12 @@
+/* { dg-do run } */
+/* { dg-additional-options "-mtrack-speculation" } */
+/* Ensure the speculation tracker code does not invalidate the
+   stack pointer capability.  */
+
+int
+main() {
+  int a = 10;
+  while (a)
+    a--;
+  return 0;
+}