[gcc r14-10135] bpf: set PREFERRED_DEBUGGING_TYPE to BTF_DEBUG

[gcc r14-10135] bpf: set PREFERRED_DEBUGGING_TYPE to BTF_DEBUG

[David Faust]

https://gcc.gnu.org/g:1604f7cebc49220e47d584615bcd91b1fdc1267f

commit r14-10135-g1604f7cebc49220e47d584615bcd91b1fdc1267f
Author: David Faust <david.faust@oracle.com>
Date:   Wed Apr 24 15:01:02 2024 -0700

    bpf: set PREFERRED_DEBUGGING_TYPE to BTF_DEBUG
    
    BTF is the standard debug info used with BPF programs, so it makes sense
    to default to BTF rather than DWARF.
    
    gcc/
            * config/bpf/bpf.h (PREFERRED_DEBUGGING_TYPE): Set to BTF_DEBUG.
    
    gcc/testsuite/
            * gcc.target/bpf/bpf-debug-options-1.c: New test.
            * gcc.target/bpf/bpf-debug-options-2.c: Likewise.
            * gcc.target/bpf/bpf-debug-options-3.c: Likewise.
            * gcc.target/bpf/core-options-4.c: Likewise.

Diff:
---
 gcc/config/bpf/bpf.h                               |  5 +++++
 gcc/testsuite/gcc.target/bpf/bpf-debug-options-1.c | 17 +++++++++++++++++
 gcc/testsuite/gcc.target/bpf/bpf-debug-options-2.c | 18 ++++++++++++++++++
 gcc/testsuite/gcc.target/bpf/bpf-debug-options-3.c | 14 ++++++++++++++
 gcc/testsuite/gcc.target/bpf/core-options-4.c      |  4 ++++
 5 files changed, 58 insertions(+)

diff --git a/gcc/config/bpf/bpf.h b/gcc/config/bpf/bpf.h
index c67e17526bf..e163fbf688d 100644
--- a/gcc/config/bpf/bpf.h
+++ b/gcc/config/bpf/bpf.h
@@ -245,6 +245,11 @@ enum reg_class
 
 /**** Debugging Info ****/
 
+/* Use BTF debug info by default.  */
+
+#undef  PREFERRED_DEBUGGING_TYPE
+#define PREFERRED_DEBUGGING_TYPE BTF_DEBUG
+
 /* In eBPF it is not possible to unwind frames. Disable CFA.  */
 
 #define DWARF2_FRAME_INFO 0
diff --git a/gcc/testsuite/gcc.target/bpf/bpf-debug-options-1.c b/gcc/testsuite/gcc.target/bpf/bpf-debug-options-1.c
new file mode 100644
index 00000000000..409466c4ead
--- /dev/null
+++ b/gcc/testsuite/gcc.target/bpf/bpf-debug-options-1.c
@@ -0,0 +1,17 @@
+/* Default to BTF debug info.  */
+/* { dg-do compile } */
+/* { dg-options "-g -dA" }*/
+
+struct A {
+  int x;
+  int y;
+};
+
+int
+foo (struct A *a)
+{
+  return a->x;
+}
+
+/* { dg-final { scan-assembler-not "DWARF version" } } */
+/* { dg-final { scan-assembler "btf_version" } } */
diff --git a/gcc/testsuite/gcc.target/bpf/bpf-debug-options-2.c b/gcc/testsuite/gcc.target/bpf/bpf-debug-options-2.c
new file mode 100644
index 00000000000..03bde12315b
--- /dev/null
+++ b/gcc/testsuite/gcc.target/bpf/bpf-debug-options-2.c
@@ -0,0 +1,18 @@
+/* -g defaults to BTF, which in turn implies -mco-re.  */
+/* { dg-do compile } */
+/* { dg-options "-g -dA" }*/
+
+struct A {
+  int x;
+  int y;
+};
+
+int
+foo (struct A *a)
+{
+  return __builtin_preserve_access_index (a->x);
+}
+
+/* { dg-final { scan-assembler-not "DWARF version" } } */
+/* { dg-final { scan-assembler "btf_version" } } */
+/* { dg-final { scan-assembler "btfext_version" } } */
diff --git a/gcc/testsuite/gcc.target/bpf/bpf-debug-options-3.c b/gcc/testsuite/gcc.target/bpf/bpf-debug-options-3.c
new file mode 100644
index 00000000000..d41790e0928
--- /dev/null
+++ b/gcc/testsuite/gcc.target/bpf/bpf-debug-options-3.c
@@ -0,0 +1,14 @@
+/* Using -g does not incorrectly force CO-RE enabled.  */
+/* { dg-do compile } */
+/* { dg-options "-g -dA -mno-co-re" }*/
+
+struct A {
+  int x;
+  int y;
+};
+
+int
+foo (struct A *a)
+{
+  return __builtin_preserve_access_index (a->x); /* { dg-error "BPF CO-RE is required" } */
+}
diff --git a/gcc/testsuite/gcc.target/bpf/core-options-4.c b/gcc/testsuite/gcc.target/bpf/core-options-4.c
new file mode 100644
index 00000000000..fde4195da42
--- /dev/null
+++ b/gcc/testsuite/gcc.target/bpf/core-options-4.c
@@ -0,0 +1,4 @@
+/* -g implies BTF, -gtoggle turns it off.  CO-RE should not work.  */
+/* { dg-do compile } */
+/* { dg-options "-g -mco-re -gtoggle" } */
+/* { dg-excess-errors "BPF CO-RE requires BTF debugging information" } */