| Message ID | 20220106083840.GV2646553@tucnak |
|---|---|
| State | New |
| Headers | show |
| Series | expr: Workaround profiledbootstrap uninit false positive [PR103899] | expand |
On January 6, 2022 9:38:40 AM GMT+01:00, Jakub Jelinek via Gcc-patches <gcc-patches@gcc.gnu.org> wrote: >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? Ok. Richard. >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. > >--- 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 >
--- 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.
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 <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. Jakub