[gcc r10-11122] AArch64: Add UNSPECV_PATCHABLE_AREA [PR98776]

[gcc r10-11122] AArch64: Add UNSPECV_PATCHABLE_AREA [PR98776]

[Sebastian Pop]

https://gcc.gnu.org/g:59bba6f9dc6dcfefe96e6fad677614f39928564e

commit r10-11122-g59bba6f9dc6dcfefe96e6fad677614f39928564e
Author: Sebastian Pop <spop@amazon.com>
Date:   Wed Nov 30 19:45:24 2022 +0000

    AArch64: Add UNSPECV_PATCHABLE_AREA [PR98776]
    
    Currently patchable area is at the wrong place on AArch64.  It is placed
    immediately after function label, before .cfi_startproc.  This patch
    adds UNSPECV_PATCHABLE_AREA for pseudo patchable area instruction and
    modifies aarch64_print_patchable_function_entry to avoid placing
    patchable area before .cfi_startproc.
    
    gcc/
            PR target/98776
            * config/aarch64/aarch64-protos.h (aarch64_output_patchable_area):
            Declared.
            * config/aarch64/aarch64.c (aarch64_print_patchable_function_entry):
            Emit an UNSPECV_PATCHABLE_AREA pseudo instruction.
            (aarch64_output_patchable_area): New.
            * config/aarch64/aarch64.md (UNSPECV_PATCHABLE_AREA): New.
            (patchable_area): Define.
    
    gcc/testsuite/
            PR target/98776
            * gcc.target/aarch64/pr98776.c: New.
            * gcc.target/aarch64/pr92424-2.c: Adjust pattern.
            * gcc.target/aarch64/pr92424-3.c: Adjust pattern.

Diff:
---
 gcc/config/aarch64/aarch64-protos.h          |  2 +
 gcc/config/aarch64/aarch64.c                 | 56 ++++++++++++++++++++--------
 gcc/config/aarch64/aarch64.md                | 14 +++++++
 gcc/testsuite/gcc.target/aarch64/pr92424-2.c |  2 +-
 gcc/testsuite/gcc.target/aarch64/pr92424-3.c |  2 +-
 gcc/testsuite/gcc.target/aarch64/pr98776.c   | 11 ++++++
 6 files changed, 70 insertions(+), 17 deletions(-)

diff --git a/gcc/config/aarch64/aarch64-protos.h b/gcc/config/aarch64/aarch64-protos.h
index 61e2ad54f88..ef24c48fc14 100644
--- a/gcc/config/aarch64/aarch64-protos.h
+++ b/gcc/config/aarch64/aarch64-protos.h
@@ -805,4 +805,6 @@ const char *aarch64_indirect_call_asm (rtx);
 extern bool aarch64_harden_sls_retbr_p (void);
 extern bool aarch64_harden_sls_blr_p (void);
 
+extern void aarch64_output_patchable_area (unsigned int, bool);
+
 #endif /* GCC_AARCH64_PROTOS_H */
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 67c2f1123b4..dd9a3832b5a 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -19498,30 +19498,56 @@ aarch64_declare_function_name (FILE *stream, const char* name,
   cfun->machine->label_is_assembled = true;
 }
 
-/* Implement PRINT_PATCHABLE_FUNCTION_ENTRY.  Check if the patch area is after
-   the function label and emit a BTI if necessary.  */
+/* Implement PRINT_PATCHABLE_FUNCTION_ENTRY.  */
 
 void
 aarch64_print_patchable_function_entry (FILE *file,
 					unsigned HOST_WIDE_INT patch_area_size,
 					bool record_p)
 {
-  if (cfun->machine->label_is_assembled
-      && aarch64_bti_enabled ()
-      && !cgraph_node::get (cfun->decl)->only_called_directly_p ())
+  if (!cfun->machine->label_is_assembled)
     {
-      /* Remove the BTI that follows the patch area and insert a new BTI
-	 before the patch area right after the function label.  */
-      rtx_insn *insn = next_real_nondebug_insn (get_insns ());
-      if (insn
-	  && INSN_P (insn)
-	  && GET_CODE (PATTERN (insn)) == UNSPEC_VOLATILE
-	  && XINT (PATTERN (insn), 1) == UNSPECV_BTI_C)
-	delete_insn (insn);
-      asm_fprintf (file, "\thint\t34 // bti c\n");
+      /* Emit the patching area before the entry label, if any.  */
+      default_print_patchable_function_entry (file, patch_area_size,
+					      record_p);
+      return;
+    }
+
+  rtx pa = gen_patchable_area (GEN_INT (patch_area_size),
+			       GEN_INT (record_p));
+  basic_block bb = ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb;
+
+  if (!aarch64_bti_enabled ()
+      || cgraph_node::get (cfun->decl)->only_called_directly_p ())
+    {
+      /* Emit the patchable_area at the beginning of the function.  */
+      rtx_insn *insn = emit_insn_before (pa, BB_HEAD (bb));
+      INSN_ADDRESSES_NEW (insn, -1);
+      return;
+    }
+
+  rtx_insn *insn = next_real_nondebug_insn (get_insns ());
+  if (!insn
+      || !INSN_P (insn)
+      || GET_CODE (PATTERN (insn)) != UNSPEC_VOLATILE
+      || XINT (PATTERN (insn), 1) != UNSPECV_BTI_C)
+    {
+      /* Emit a BTI_C.  */
+      insn = emit_insn_before (gen_bti_c (), BB_HEAD (bb));
     }
 
-  default_print_patchable_function_entry (file, patch_area_size, record_p);
+  /* Emit the patchable_area after BTI_C.  */
+  insn = emit_insn_after (pa, insn);
+  INSN_ADDRESSES_NEW (insn, -1);
+}
+
+/* Output patchable area.  */
+
+void
+aarch64_output_patchable_area (unsigned int patch_area_size, bool record_p)
+{
+  default_print_patchable_function_entry (asm_out_file, patch_area_size,
+					  record_p);
 }
 
 /* Implement ASM_OUTPUT_DEF_FROM_DECLS.  Output .variant_pcs for aliases.  */
diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index 552aed3ce89..96e72bc6c06 100644
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -282,6 +282,7 @@
     UNSPEC_TAG_SPACE		; Translate address to MTE tag address space.
     UNSPEC_LD1RO
     UNSPEC_SALT_ADDR
+    UNSPECV_PATCHABLE_AREA
 ])
 
 (define_c_enum "unspecv" [
@@ -7606,6 +7607,19 @@
   [(set_attr "type" "memtag")]
 )
 
+(define_insn "patchable_area"
+  [(unspec_volatile [(match_operand 0 "const_int_operand")
+		     (match_operand 1 "const_int_operand")]
+		    UNSPECV_PATCHABLE_AREA)]
+  ""
+{
+  aarch64_output_patchable_area (INTVAL (operands[0]),
+			         INTVAL (operands[1]) != 0);
+  return "";
+}
+  [(set (attr "length") (symbol_ref "INTVAL (operands[0])"))]
+)
+
 ;; AdvSIMD Stuff
 (include "aarch64-simd.md")
 
diff --git a/gcc/testsuite/gcc.target/aarch64/pr92424-2.c b/gcc/testsuite/gcc.target/aarch64/pr92424-2.c
index 0e75657a153..86bb92e6f32 100644
--- a/gcc/testsuite/gcc.target/aarch64/pr92424-2.c
+++ b/gcc/testsuite/gcc.target/aarch64/pr92424-2.c
@@ -9,4 +9,4 @@ __attribute__ ((target("branch-protection=bti"),
 f10_bti ()
 {
 }
-/* { dg-final { scan-assembler "f10_bti:\n\thint\t34 // bti c\n.*\.LPFE1:\n\tnop\n.*\tret\n" } } */
+/* { dg-final { scan-assembler "hint\t34 // bti c\n.*\.LPFE1:\n\tnop\n.*\tret\n" } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/pr92424-3.c b/gcc/testsuite/gcc.target/aarch64/pr92424-3.c
index 0a1f74d4096..daac2faf18e 100644
--- a/gcc/testsuite/gcc.target/aarch64/pr92424-3.c
+++ b/gcc/testsuite/gcc.target/aarch64/pr92424-3.c
@@ -9,4 +9,4 @@ __attribute__ ((target("branch-protection=bti+pac-ret+leaf"),
 f10_pac ()
 {
 }
-/* { dg-final { scan-assembler "f10_pac:\n\thint\t34 // bti c\n.*\.LPFE1:\n\tnop\n.*\thint\t25 // paciasp\n.*\thint\t29 // autiasp\n.*\tret\n" } } */
+/* { dg-final { scan-assembler "hint\t34 // bti c\n.*\.LPFE1:\n\tnop\n.*\thint\t25 // paciasp\n.*\thint\t29 // autiasp\n.*\tret\n" } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/pr98776.c b/gcc/testsuite/gcc.target/aarch64/pr98776.c
new file mode 100644
index 00000000000..d193df8e66d
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/pr98776.c
@@ -0,0 +1,11 @@
+/* { dg-do "compile" } */
+/* { dg-options "-O1 -fpatchable-function-entry=1 -fasynchronous-unwind-tables" } */
+
+/* Test the placement of the .LPFE1 label.  */
+
+void
+foo (void)
+{
+}
+
+/* { dg-final { scan-assembler "\t\.cfi_startproc\n.*\.LPFE1:\n\tnop\n\tret\n" } } */