Hi, This is the 2nd version of the patch. The original patch is at:
https://gcc.gnu.org/pipermail/gcc-patches/2021-December/586341.html In addition to resolve the two issues mentioned in the original patch, This patch also can be used as a very good workaround for the issue in PR103720 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103720 And as I checked, the patch can fix all the bogus uninitialized warnings when building kernel with -O2 + -ftrivial-auto-var-init=zero + -Wuninitialized. So, this is a very important patch that need to be included into gcc12. Compared to the 1st patch, the major changes are to resolve Martin’s comments on tree-ssa-uninit.c 1. Add some meaningful temporaries to break the long expression to make it Readable. And also add comments to explain the purpose of the statement; 2. Resolve the memory leakage of the dynamically created string. The patch has been bootstrapped and regressing tested on both x86 and aarch64, no issues. Okay for commit? thanks. Qing ================================================= ******Compared to the 1st version, the code change is: --- a/gcc/tree-ssa-uninit.c +++ b/gcc/tree-ssa-uninit.c @@ -182,9 +182,22 @@ warn_uninit (opt_code opt, tree t, tree var, const char *gmsgid, @@ -798,26 +798,35 @@ if (!var && !SSA_NAME_VAR (t)) { gimple *def_stmt = SSA_NAME_DEF_STMT (t); -@@ -197,9 +210,34 @@ warn_uninit (opt_code opt, tree t, tree var, const char *gmsgid, +@@ -197,9 +210,43 @@ warn_uninit (opt_code opt, tree t, tree var, const char *gmsgid, && zerop (gimple_assign_rhs2 (def_stmt))) var = SSA_NAME_VAR (v); } + + if (gimple_call_internal_p (def_stmt, IFN_DEFERRED_INIT)) + { ++ tree lhs_var = NULL_TREE; ++ tree lhs_var_name = NULL_TREE; ++ const char *lhs_var_name_str = NULL; + /* Get the variable name from the 3rd argument of call. */ + var_name = gimple_call_arg (def_stmt, 2); + var_name = TREE_OPERAND (TREE_OPERAND (var_name, 0), 0); + var_name_str = TREE_STRING_POINTER (var_name); + -+ if (is_gimple_assign (context) -+ && TREE_CODE (gimple_assign_lhs (context)) == VAR_DECL -+ && DECL_NAME (gimple_assign_lhs (context)) -+ && IDENTIFIER_POINTER (DECL_NAME (gimple_assign_lhs (context)))) -+ if (strcmp -+ (IDENTIFIER_POINTER (DECL_NAME (gimple_assign_lhs (context))), -+ var_name_str) == 0) -+ return; ++ /* Ignore the call to .DEFERRED_INIT that define the original ++ var itself. */ ++ if (is_gimple_assign (context)) ++ { ++ if (TREE_CODE (gimple_assign_lhs (context)) == VAR_DECL) ++ lhs_var = gimple_assign_lhs (context); ++ else if (TREE_CODE (gimple_assign_lhs (context)) == SSA_NAME) ++ lhs_var = SSA_NAME_VAR (gimple_assign_lhs (context)); ++ } ++ if (lhs_var ++ && (lhs_var_name = DECL_NAME (lhs_var)) ++ && (lhs_var_name_str = IDENTIFIER_POINTER (lhs_var_name)) ++ && (strcmp (lhs_var_name_str, var_name_str) == 0)) ++ return; + + /* Get the variable declaration location from the def_stmt. */ + var_decl_loc = gimple_location (def_stmt); @@ -834,7 +843,7 @@ return; /* Avoid warning if we've already done so or if the warning has been -@@ -207,36 +245,56 @@ warn_uninit (opt_code opt, tree t, tree var, const char *gmsgid, +@@ -207,36 +254,54 @@ warn_uninit (opt_code opt, tree t, tree var, const char *gmsgid, if (((warning_suppressed_p (context, OPT_Wuninitialized) || (gimple_assign_single_p (context) && get_no_uninit_warning (gimple_assign_rhs1 (context))))) @@ -863,25 +872,24 @@ auto_diagnostic_group d; - if (!warning_at (location, opt, gmsgid, var)) +- return; + char *gmsgid_final = XNEWVEC (char, strlen (gmsgid) + 5); + gmsgid_final[0] = 0; -+ if (var) -+ strcat (gmsgid_final, "%qD "); -+ else if (var_name) -+ strcat (gmsgid_final, "%qs "); ++ strcat (gmsgid_final, var ? "%qD " : "%qs "); + strcat (gmsgid_final, gmsgid); + -+ if (var && !warning_at (location, opt, gmsgid_final, var)) -+ return; -+ else if (var_name && !warning_at (location, opt, gmsgid_final, var_name_str)) - return; ++ if ((var && !warning_at (location, opt, gmsgid_final, var)) ++ || (var_name && !warning_at (location, opt, gmsgid_final, var_name_str))) ++ { ++ XDELETE (gmsgid_final); ++ return; ++ } ++ XDELETE (gmsgid_final); /* Avoid subsequent warnings for reads of the same variable again. */ - suppress_warning (var, opt); -+ if (var) -+ suppress_warning (var, opt); -+ else if (repl_var) -+ suppress_warning (repl_var, opt); ++ if (var || repl_var) ++ suppress_warning (var ? var : repl_var, opt); /* Issue a note pointing to the read variable unless the warning is at the same location. */ @@ -898,7 +906,7 @@ } ******The complete patch is:
0001-Enable-Wuninitialized-ftrivial-auto-var-init-for-add.patch
Description: 0001-Enable-Wuninitialized-ftrivial-auto-var-init-for-add.patch
