[gcc r11-9505] dwarf2out: Fix -gsplit-dwarf on riscv [PR103874]

[gcc r11-9505] dwarf2out: Fix -gsplit-dwarf on riscv [PR103874]

[Jakub Jelinek]

https://gcc.gnu.org/g:3991e4c752b3450decdb36e0b562e044ce653b3d

commit r11-9505-g3991e4c752b3450decdb36e0b562e044ce653b3d
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Thu Jan 20 11:58:20 2022 +0100

    dwarf2out: Fix -gsplit-dwarf on riscv [PR103874]
    
    riscv*-*-* are the only modern targets that !HAVE_AS_LEB128 (apparently
    due to some aggressive linker optimizations).
    As the following testcase shows, we mishandle in index_rnglists the
    !HAVE_AS_LEB128 && !have_multiple_function_sections case.
    
    output_rnglists does roughly:
      FOR_EACH_VEC_SAFE_ELT (ranges_table, i, r)
        {
    ...
          if (block_num > 0)
            {
    ...
              if (HAVE_AS_LEB128)
                {
                  if (!have_multiple_function_sections)
                    {
                      // code not using r->*_entry
                      continue;
                    }
                  // code that sometimes doesn't use r->*_entry,
                  // sometimes r->begin_entry
                }
              else if (dwarf_split_debug_info)
                {
                  // code that uses both r->begin_entry and r->end_entry
                }
              else
                {
                  // code not using r->*_entry
                }
            }
          else if (block_num < 0)
            {
              if (!have_multiple_function_sections)
                gcc_unreachable ();
    ...
            }
        }
    and index_rnglists is what sets up those r->{begin,end}_entry members.
    The code did an early if (!have_multiple_function_sections) continue;
    which is fine for the HAVE_AS_LEB128 case, because r->*_entry is not
    used in that case, but not for !HAVE_AS_LEB128 that uses it anyway.
    
    2022-01-20  Jakub Jelinek  <jakub@redhat.com>
    
            PR debug/103874
            * dwarf2out.c (index_rnglists): For !HAVE_AS_LEB128 and
            block_num > 0, index entry even if !have_multiple_function_sections.
    
            * gcc.dg/debug/dwarf2/pr103874.c: New test.
    
    (cherry picked from commit 68f03ac49cb4f585dbce78dc9e4c4a9ec950e83c)

Diff:
---
 gcc/dwarf2out.c                              |  5 +++--
 gcc/testsuite/gcc.dg/debug/dwarf2/pr103874.c | 12 ++++++++++++
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index d74c8e3867f..e5d3ce4966d 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -11961,9 +11961,10 @@ index_rnglists (void)
       if (r->label && r->idx != DW_RANGES_IDX_SKELETON)
 	r->idx = rnglist_idx++;
 
-      if (!have_multiple_function_sections)
-	continue;
       int block_num = r->num;
+      if ((HAVE_AS_LEB128 || block_num < 0)
+	  && !have_multiple_function_sections)
+	continue;
       if (HAVE_AS_LEB128 && (r->label || r->maybe_new_sec))
 	base = false;
       if (block_num > 0)
diff --git a/gcc/testsuite/gcc.dg/debug/dwarf2/pr103874.c b/gcc/testsuite/gcc.dg/debug/dwarf2/pr103874.c
new file mode 100644
index 00000000000..2f0e2d44e42
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/debug/dwarf2/pr103874.c
@@ -0,0 +1,12 @@
+/* PR debug/103874 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -g -gsplit-dwarf -dA -Wno-implicit-function-declaration" } */
+
+void
+foo (void)
+{
+  {
+    bar ();
+    baz ();
+  }
+}