[gcc r16-1522] aarch64: add debug comments to feature properties in .note.gnu.property

[Matthieu Longo]

https://gcc.gnu.org/g:6eb0dc067dad1fe745e83d4e113c1b2ea0ffed8c

commit r16-1522-g6eb0dc067dad1fe745e83d4e113c1b2ea0ffed8c
Author: Matthieu Longo <matthieu.longo@arm.com>
Date:   Mon Sep 23 14:38:57 2024 +0100

    aarch64: add debug comments to feature properties in .note.gnu.property
    
    GNU properties are emitted to provide some information about the features
    used in the generated code like BTI, GCS, or PAC. However, no debug
    comment are emitted in the generated assembly even if -dA is provided.
    It makes understanding the information stored in the .note.gnu.property
    section more difficult than needed.
    
    This patch adds assembly comments (if -dA is provided) next to the GNU
    properties. For instance, if BTI and PAC are enabled, it will emit:
      .word  0x3  // GNU_PROPERTY_AARCH64_FEATURE_1_AND (BTI, PAC)
    
    gcc/ChangeLog:
    
            * config/aarch64/aarch64.cc
            (aarch64_file_end_indicate_exec_stack): Emit assembly comments.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.target/aarch64/bti-1.c: Emit assembly comments, and update
            test assertion.

Diff:
---
 gcc/config/aarch64/aarch64.cc            | 35 ++++++++++++++++++++++++++++++--
 gcc/testsuite/gcc.target/aarch64/bti-1.c | 13 ++++++------
 2 files changed, 40 insertions(+), 8 deletions(-)

diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc
index c8977b5a9481..f2c9322da584 100644
--- a/gcc/config/aarch64/aarch64.cc
+++ b/gcc/config/aarch64/aarch64.cc
@@ -30006,10 +30006,41 @@ aarch64_file_end_indicate_exec_stack ()
 	 type   = GNU_PROPERTY_AARCH64_FEATURE_1_AND
 	 datasz = 4
 	 data   = feature_1_and.  */
-      assemble_integer (GEN_INT (GNU_PROPERTY_AARCH64_FEATURE_1_AND), 4, 32, 1);
+      fputs (integer_asm_op (4, true), asm_out_file);
+      fprint_whex (asm_out_file, GNU_PROPERTY_AARCH64_FEATURE_1_AND);
+      putc ('\n', asm_out_file);
       assemble_integer (GEN_INT (4), 4, 32, 1);
-      assemble_integer (GEN_INT (feature_1_and), 4, 32, 1);
 
+      fputs (integer_asm_op (4, true), asm_out_file);
+      fprint_whex (asm_out_file, feature_1_and);
+      if (flag_debug_asm)
+	{
+	  struct flag_name
+	  {
+	    unsigned int mask;
+	    const char *name;
+	  };
+	  static const flag_name flags[] = {
+	    { GNU_PROPERTY_AARCH64_FEATURE_1_BTI, "BTI" },
+	    { GNU_PROPERTY_AARCH64_FEATURE_1_PAC, "PAC" },
+	    { GNU_PROPERTY_AARCH64_FEATURE_1_GCS, "GCS" },
+	  };
+
+	  const char *separator = "";
+	  std::string s_features;
+	  for (auto &flag : flags)
+	    if (feature_1_and & flag.mask)
+	      {
+		s_features.append (separator).append (flag.name);
+		separator = ", ";
+	      }
+
+	  asm_fprintf (asm_out_file,
+		       "\t%s GNU_PROPERTY_AARCH64_FEATURE_1_AND (%s)\n",
+		       ASM_COMMENT_START, s_features.c_str ());
+	}
+      else
+	putc ('\n', asm_out_file);
       /* Pad the size of the note to the required alignment.  */
       assemble_align (POINTER_SIZE);
     }
diff --git a/gcc/testsuite/gcc.target/aarch64/bti-1.c b/gcc/testsuite/gcc.target/aarch64/bti-1.c
index 5a556b08ed15..53dc2d3cd8b2 100644
--- a/gcc/testsuite/gcc.target/aarch64/bti-1.c
+++ b/gcc/testsuite/gcc.target/aarch64/bti-1.c
@@ -1,6 +1,6 @@
 /* { dg-do compile } */
 /* -Os to create jump table.  */
-/* { dg-options "-Os" } */
+/* { dg-options "-Os -dA" } */
 /* { dg-require-effective-target lp64 } */
 /* If configured with --enable-standard-branch-protection, don't use
    command line option.  */
@@ -44,8 +44,8 @@ f_jump_table (int y, int n)
   return (y == 0)? y+1:4;
 }
 /* f_jump_table should have PACIASP and AUTIASP.  */
-/* { dg-final { scan-assembler-times "hint\t25" 1 } } */
-/* { dg-final { scan-assembler-times "hint\t29" 1 } } */
+/* { dg-final { scan-assembler-times "hint\t25 // paciasp" 1 } } */
+/* { dg-final { scan-assembler-times "hint\t29 // autiasp" 1 } } */
 
 int
 f_label_address ()
@@ -59,6 +59,7 @@ lab2:
   addr = &&lab1;
   return 2;
 }
-/* { dg-final { scan-assembler-times "hint\t34" 1 } } */
-/* { dg-final { scan-assembler-times "hint\t36" 12 } } */
-/* { dg-final { scan-assembler ".note.gnu.property" { target *-*-linux* } } } */
+/* { dg-final { scan-assembler-times "hint\t34 // bti c" 1 } } */
+/* { dg-final { scan-assembler-times "hint\t36 // bti j" 12 } } */
+/* { dg-final { scan-assembler "\.section\t\.note\.gnu\.property" { target *-*-linux* } } } */
+/* { dg-final { scan-assembler "\.word\t0x7\t\/\/ GNU_PROPERTY_AARCH64_FEATURE_1_AND \\(BTI, PAC, GCS\\)" { target *-*-linux* } } } */
\ No newline at end of file