Hi!
The threader changes resulted in a false positive warning during
profiledbootstrap:
In file included from ../../gcc/expr.c:26:
../../gcc/tree.h: In function ‘rtx_def* expand_expr_real_1(tree, rtx,
machine_mode, expand_modifier, rtx_def**, bool)’:
../../gcc/tree.h:244:56: error: ‘context’ may be used uninitialized in this
function [-Werror=maybe-uninitialized]
244 | #define TREE_CODE(NODE) ((enum tree_code) (NODE)->base.code)
| ^~~~
../../gcc/expr.c:10343:8: note: ‘context’ was declared here
10343 | tree context;
| ^~~~~~~
While it will be nice to improve the uninit pass to handle it if possible
(I do not want to close the PR until that is done), doing profiledbootstrap
is a common thing to do, so a workaround is handy, especially as in this
case when the workaround seems to be the right thing to do, as it moves
a variable declaration to the only place where it is set and used and avoids
the weird and for uninit asking
tree context;
...
if (exp)
context = ...;
gcc_assert (!exp
|| use (context)
|| use_some_more (context));
Bootstrapped/regtested on x86_64-linux and i686-linux with normal bootstrap
and on aarch64-linux and powerpc64le-linux with profiledbootstrap, ok for
trunk?
2022-01-06 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/103899
* expr.c (expand_expr_real_1): Add a workaround for bogus uninit
warning by moving context variable to the only spot where it is used
and moving gcc_assert into if body.
--- gcc/expr.c.jj 2022-01-03 10:40:41.203164211 +0100
+++ gcc/expr.c 2022-01-05 14:47:47.684660031 +0100
@@ -10340,7 +10340,6 @@ expand_expr_real_1 (tree exp, rtx target
enum tree_code code = TREE_CODE (exp);
rtx subtarget, original_target;
int ignore;
- tree context;
bool reduce_bit_field;
location_t loc = EXPR_LOCATION (exp);
struct separate_ops ops;
@@ -10579,14 +10578,16 @@ expand_expr_real_1 (tree exp, rtx target
/* Variables inherited from containing functions should have
been lowered by this point. */
if (exp)
- context = decl_function_context (exp);
- gcc_assert (!exp
- || SCOPE_FILE_SCOPE_P (context)
- || context == current_function_decl
- || TREE_STATIC (exp)
- || DECL_EXTERNAL (exp)
- /* ??? C++ creates functions that are not TREE_STATIC. */
- || TREE_CODE (exp) == FUNCTION_DECL);
+ {
+ tree context = decl_function_context (exp);
+ gcc_assert (SCOPE_FILE_SCOPE_P (context)
+ || context == current_function_decl
+ || TREE_STATIC (exp)
+ || DECL_EXTERNAL (exp)
+ /* ??? C++ creates functions that are not
+ TREE_STATIC. */
+ || TREE_CODE (exp) == FUNCTION_DECL);
+ }
/* This is the case of an array whose size is to be determined
from its initializer, while the initializer is still being parsed.
Jakub
