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From: Jakub Jelinek <jakub@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r12-6280] expr: Workaround profiledbootstrap uninit false positive [PR103899] Date: Thu, 6 Jan 2022 14:33:35 +0000 (GMT) [thread overview] Message-ID: <20220106143335.8CFEB3858C3A@sourceware.org> (raw) https://gcc.gnu.org/g:db33b1059bcee3eeb36d174d59abf19f2bef5d66 commit r12-6280-gdb33b1059bcee3eeb36d174d59abf19f2bef5d66 Author: Jakub Jelinek <jakub@redhat.com> Date: Thu Jan 6 15:32:57 2022 +0100 expr: Workaround profiledbootstrap uninit false positive [PR103899] 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)); 2022-01-06 Jakub Jelinek <jakub@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. Diff: --- gcc/expr.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) diff --git a/gcc/expr.c b/gcc/expr.c index 7fa001f9e5c..9fb018766a6 100644 --- a/gcc/expr.c +++ b/gcc/expr.c @@ -10340,7 +10340,6 @@ expand_expr_real_1 (tree exp, rtx target, machine_mode tmode, 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, machine_mode tmode, /* 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.
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