[Bug c++/104180] [10/11/12 Regression] '-fcompare-debug' failure (length) w/ -O1

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104180

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|middle-end                  |c++

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
[apinski@xeond2 src]$ diff -up t.cc.*original t.gk.cc.*original |less
--- t.cc.005t.original  2022-01-22 03:44:26.901343652 -0800
+++ t.gk.cc.005t.original       2022-01-22 03:44:27.005343663 -0800
@@ -6,13 +6,19 @@
 {
   unsigned int b;

+  # DEBUG BEGIN STMT;
     unsigned int b;
+  # DEBUG BEGIN STMT;
   <<cleanup_point <<< Unknown tree: expr_stmt
     (void) (b = 3) >>>>>;
   <D.2374>:;
+  # DEBUG BEGIN STMT;
   <<cleanup_point <<< Unknown tree: expr_stmt
-    (void) (a[b] = a[b + 1]) >>>>>;
+    (void) (a[b] = # DEBUG BEGIN STMT;
+    a[b + 1];) >>>>>;
+  # DEBUG BEGIN STMT;
   <<cleanup_point (void) b-- >>;
+  # DEBUG BEGIN STMT;
   goto <D.2374>;
 }



And then we gimplify:
+  # DEBUG BEGIN_STMT
+  # DEBUG BEGIN_STMT
   b = 3;
   <D.2374>:
-  _1 = b + 1;
-  _2 = a[_1];
-  a[b] = _2;
+  # DEBUG BEGIN_STMT
+  _1 = &a[b];
+  # DEBUG BEGIN_STMT
+  _2 = b + 1;
+  _3 = a[_2];
+  *_1 = _3;
+  # DEBUG BEGIN_STMT
   b = b + 4294967295;
+  # DEBUG BEGIN_STMT
   goto <D.2374>;