[gcc r13-631] cfgexpand: Yet another spot with debug insns references to global vars without varpool nodes [PR1056

[gcc r13-631] cfgexpand: Yet another spot with debug insns references to global vars without varpool nodes [PR1056

[Jakub Jelinek]

https://gcc.gnu.org/g:213cfa8d0a9d0bb28bd973323ee2055ee6699d86

commit r13-631-g213cfa8d0a9d0bb28bd973323ee2055ee6699d86
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Thu May 19 11:58:15 2022 +0200

    cfgexpand: Yet another spot with debug insns references to global vars without varpool nodes [PR105630]
    
    This is similar to the earlier patch to avoid having MEM_EXPRs
    referencing global vars without varpool nodes, but this time
    the difference is that during gimplification some hashing
    actually created DECL_RTLs for the n VAR_DECL and the previous
    change was in the if above this when DECL_RTL is NULL and we are
    considering creating it.
    
    The following patch drops on the floor references to vars where
    we've optimized away the varpool node even when it has DECL_RTL.
    
    Bootstrapped/regtested on x86_64-linux and i686-linux, plus
    bootstrapped on those without the cfgexpand.cc change, reapplied
    it and rebuilt stage3 cc1/cc1plus, the resulting cc1/cc1plus
    binaries on both targets were identical except for the 16-byte
    executable_checksum (I've done the second bootstraps in the same
    directory as the first one after moving the previous one elsewhere,
    so pathnames were the same, just checksum hasn't been regenerated).
    So, at least on those binaries this patch doesn't affect debug info
    at all.
    
    2022-05-19  Jakub Jelinek  <jakub@redhat.com>
    
            PR debug/105630
            * cfgexpand.cc (expand_debug_expr): For VAR_DECL, punt for
            global vars without symtab node even when they have DECL_RTL
            set.
    
            * gcc.dg/pr105630.c: New test.

Diff:
---
 gcc/cfgexpand.cc                |  4 ++++
 gcc/testsuite/gcc.dg/pr105630.c | 22 ++++++++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/gcc/cfgexpand.cc b/gcc/cfgexpand.cc
index 49b91827e83..bb33c1b939e 100644
--- a/gcc/cfgexpand.cc
+++ b/gcc/cfgexpand.cc
@@ -4575,6 +4575,10 @@ expand_debug_expr (tree exp)
 	      || SYMBOL_REF_DECL (XEXP (op0, 0)) != exp)
 	    return NULL;
 	}
+      else if (VAR_P (exp)
+	       && is_global_var (exp)
+	       && symtab_node::get (exp) == NULL)
+	return NULL;
       else
 	op0 = copy_rtx (op0);
 
diff --git a/gcc/testsuite/gcc.dg/pr105630.c b/gcc/testsuite/gcc.dg/pr105630.c
new file mode 100644
index 00000000000..c39ca7dda27
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr105630.c
@@ -0,0 +1,22 @@
+/* PR debug/105630 */
+/* { dg-do compile { target pthread } } */
+/* { dg-options "-O1 -ftree-parallelize-loops=2 -fcompare-debug" } */
+
+int m;
+static int n;
+
+void
+foo (void)
+{
+  int *arr[] = { &n, &n, &n };
+  int unused = n;
+
+  m = 0;
+}
+
+void
+bar (int *arr, int i)
+{
+  while (i < 1)
+    arr[i++] = 1;
+}