Hello,

I've been playing with a cross-compiler built with ASAN for
target=xtensa-linux-uclibc and I was consistently getting a
report for out-of-bound heap access inside IRA. I was able
to get the same report for target=microblazeel-linux-gnu so
it does not look entirely target-specific. I also tried earlier gcc
releases and the issue can be reproduced as early as with
gcc-7.1.0 (I had build issues with earlier versions).

AFAICS inside the functions update_costs_from_allocno and
assign_hard_reg the macro ALLOCNO_COLOR_DATA
may be applied to objects of type 'struct ira_allocno' whose
add_data field wasn't changed in the function color_pass to
point to a memory area sized for struct allocno_color_data.

The following change helps exhibit this issue without ASAN:

diff --git a/gcc/ira-color.cc b/gcc/ira-color.cc
index 4a1a325e8e31..8feacf91ff81 100644
--- a/gcc/ira-color.cc
+++ b/gcc/ira-color.cc
@@ -167,7 +167,7 @@ typedef struct allocno_color_data *allocno_color_data_t;
static allocno_color_data_t allocno_color_data;

/* Macro to access the data concerning coloring.  */
-#define ALLOCNO_COLOR_DATA(a) ((allocno_color_data_t) ALLOCNO_ADD_DATA (a))
+#define ALLOCNO_COLOR_DATA(a) (ira_assert (a->data_is_color),
(allocno_color_data_t) ALLOCNO_ADD_DATA (a))

/* Used for finding allocno colorability to exclude repeated allocno
   processing and for updating preferencing to exclude repeated
@@ -3621,6 +3621,7 @@ color_pass (ira_loop_tree_node_t loop_tree_node)
    {
      a = ira_allocnos[j];
      ALLOCNO_ADD_DATA (a) = allocno_color_data + n;
+      a->data_is_color = true;
      n++;
    }
  init_allocno_threads ();
@@ -3749,6 +3750,7 @@ color_pass (ira_loop_tree_node_t loop_tree_node)
    {
      a = ira_allocnos[j];
      ALLOCNO_ADD_DATA (a) = NULL;
+      a->data_is_color = false;
    }
}

diff --git a/gcc/ira-int.h b/gcc/ira-int.h
index f42a314fa7f4..a5d8d70f368c 100644
--- a/gcc/ira-int.h
+++ b/gcc/ira-int.h
@@ -416,6 +416,7 @@ struct ira_allocno
  /* Different additional data.  It is used to decrease size of
     allocno data footprint.  */
  void *add_data;
+  bool data_is_color;
};


The attached source triggers the above assertion in a
compiler built from revision gcc-13-3563-gf36bba013361
for target=microblazeel-linux-gnu:

$ gcc/cc1 -O2 _gcov.i
../../../../gcc/libgcc/libgcov-driver.c: In function ‘gcov_do_dump.constprop’:
../../../../gcc/libgcc/libgcov-driver.c:704:1: internal compiler
error: in assign_hard_reg, at ira-color.cc:2006

-- 
Thanks.
-- Max