Ping... Qing
Begin forwarded message: From: Qing Zhao via Gcc-patches <gcc-patches@gcc.gnu.org<mailto:gcc-patches@gcc.gnu.org>> Subject: [PATCH 2/2][middle-end/102276] Adding -Wtrivial-auto-var-init and update documentation. Date: February 19, 2022 at 10:24:09 AM CST To: richard Biener <rguent...@suse.de<mailto:rguent...@suse.de>>, Jakub Jelinek <ja...@redhat.com<mailto:ja...@redhat.com>> Cc: gcc-patches Paul A Clarke via <gcc-patches@gcc.gnu.org<mailto:gcc-patches@gcc.gnu.org>>, kees Cook <keesc...@chromium.org<mailto:keesc...@chromium.org>> Reply-To: Qing Zhao <qing.z...@oracle.com<mailto:qing.z...@oracle.com>> Hi, This is the 2nd patch for fixing pr102276. Adding -Wtrivial-auto-var-init and update documentation. Adding a new warning option -Wtrivial-auto-var-init to report cases when -ftrivial-auto-var-init cannot initialize the auto variable. At the same time, update documentation for -ftrivial-auto-var-init to connect it with the new warning option -Wtrivial-auto-var-init, and add documentation for -Wtrivial-auto-var-init. Bootstraped and regression tested on both x86 and aarch64. Okay for committing? thanks. Qing. ============================== >From 4346890b8f4258489c4841f1992ba3ce816d7689 Mon Sep 17 00:00:00 2001 From: Qing Zhao <qing.z...@oracle.com<mailto:qing.z...@oracle.com>> Date: Fri, 18 Feb 2022 15:53:15 +0000 Subject: [PATCH 2/2] Adding -Wtrivial-auto-var-init and update documentation. Adding a new warning option -Wtrivial-auto-var-init to report cases when -ftrivial-auto-var-init cannot initialize the auto variable. At the same time, update documentation for -ftrivial-auto-var-init to connect it with the new warning option -Wtrivial-auto-var-init, and add documentation for -Wtrivial-auto-var-init. 2022-02-18 Qing Zhao <qing.z...@oracle.com<mailto:qing.z...@oracle.com>> gcc/ChangeLog: * common.opt (-Wtrivial-auto-var-init): New option. * doc/invoke.texi (-Wtrivial-auto-var-init): Document new option. (-ftrivial-auto-var-init): Update option; * gimplify.cc<http://gimplify.cc> (maybe_warn_switch_unreachable): Rename... (maybe_warn_switch_unreachable_and_auto_init): ...to this. (gimplify_switch_expr): Call new function. gcc/testsuite/ChangeLog: * gcc.dg/auto-init-pr102276-3.c: New test. * gcc.dg/auto-init-pr102276-4.c: New test. --- gcc/common.opt | 4 + gcc/doc/invoke.texi | 14 ++- gcc/gimplify.cc<http://gimplify.cc> | 100 +++++++++++++++----- gcc/testsuite/gcc.dg/auto-init-pr102276-3.c | 40 ++++++++ gcc/testsuite/gcc.dg/auto-init-pr102276-4.c | 40 ++++++++ 5 files changed, 175 insertions(+), 23 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/auto-init-pr102276-3.c create mode 100644 gcc/testsuite/gcc.dg/auto-init-pr102276-4.c diff --git a/gcc/common.opt b/gcc/common.opt index c21e5273ae3..22c95dbfa49 100644 --- a/gcc/common.opt +++ b/gcc/common.opt @@ -801,6 +801,10 @@ Wtrampolines Common Var(warn_trampolines) Warning Warn whenever a trampoline is generated. +Wtrivial-auto-var-init +Common Var(warn_trivial_auto_var_init) Warning Init(0) +Warn about where -ftrivial-auto-var-init cannot initialize the auto variable. + Wtype-limits Common Var(warn_type_limits) Warning EnabledBy(Wextra) Warn if a comparison is always true or always false due to the limited range of the data type. diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index e1a00c80307..c61a5b4b4a5 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -399,7 +399,7 @@ Objective-C and Objective-C++ Dialects}. -Wswitch -Wno-switch-bool -Wswitch-default -Wswitch-enum @gol -Wno-switch-outside-range -Wno-switch-unreachable -Wsync-nand @gol -Wsystem-headers -Wtautological-compare -Wtrampolines -Wtrigraphs @gol --Wtsan -Wtype-limits -Wundef @gol +-Wtrivial-auto-var-init -Wtsan -Wtype-limits -Wundef @gol -Wuninitialized -Wunknown-pragmas @gol -Wunsuffixed-float-constants -Wunused @gol -Wunused-but-set-parameter -Wunused-but-set-variable @gol @@ -6953,6 +6953,14 @@ This warning is enabled by default for C and C++ programs. Warn when @code{__sync_fetch_and_nand} and @code{__sync_nand_and_fetch} built-in functions are used. These functions changed semantics in GCC 4.4. +@item -Wtrivial-auto-var-init +@opindex Wtrivial-auto-var-init +@opindex Wno-trivial-auto-var-init +Warn when @code{-ftrivial-auto-var-init} cannot initialize the automatic +variable. A common situation is an automatic variable that is declared +between the controlling expression and the first case lable of a @code{switch} +statement. + @item -Wunused-but-set-parameter @opindex Wunused-but-set-parameter @opindex Wno-unused-but-set-parameter @@ -12314,6 +12322,10 @@ initializer as uninitialized, @option{-Wuninitialized} and warning messages on such automatic variables. With this option, GCC will also initialize any padding of automatic variables that have structure or union types to zeroes. +However, the current implementation cannot initialize automatic variables that +are declared between the controlling expression and the first case of a +@code{switch} statement. Using @option{-Wtrivial-auto-var-init} to report all +such cases. The three values of @var{choice} are: diff --git a/gcc/gimplify.cc<http://gimplify.cc> b/gcc/gimplify.cc<http://gimplify.cc> index 4e3bbf5314d..7e52794691f 100644 --- a/gcc/gimplify.cc<http://gimplify.cc> +++ b/gcc/gimplify.cc<http://gimplify.cc> @@ -2079,13 +2079,59 @@ warn_switch_unreachable_r (gimple_stmt_iterator *gsi_p, bool *handled_ops_p, return NULL_TREE; } +/* Callback for walk_gimple_seq. */ + +static tree +warn_switch_unreachable_auto_init_r (gimple_stmt_iterator *gsi_p, + bool *handled_ops_p, + struct walk_stmt_info *) +{ + gimple *stmt = gsi_stmt (*gsi_p); + + *handled_ops_p = true; + switch (gimple_code (stmt)) + { + case GIMPLE_TRY: + case GIMPLE_BIND: + case GIMPLE_CATCH: + case GIMPLE_EH_FILTER: + case GIMPLE_TRANSACTION: + /* Walk the sub-statements. */ + *handled_ops_p = false; + break; + case GIMPLE_CALL: + if (gimple_call_internal_p (stmt, IFN_DEFERRED_INIT) + && flag_auto_var_init > AUTO_INIT_UNINITIALIZED) + { + /* Get the variable name from the 3rd argument of call. */ + tree var_name = gimple_call_arg (stmt, 2); + var_name = TREE_OPERAND (TREE_OPERAND (var_name, 0), 0); + const char *var_name_str = TREE_STRING_POINTER (var_name); + + warning_at (gimple_location (stmt), OPT_Wtrivial_auto_var_init, + "%qs cannot be initialized with" + "%<-ftrivial-auto-var_init%>", + var_name_str); + } + break; + case GIMPLE_LABEL: + /* Stop till the first Label. */ + return integer_zero_node; + default: + break; + } + return NULL_TREE; +} + /* Possibly warn about unreachable statements between switch's controlling - expression and the first case. SEQ is the body of a switch expression. */ + expression and the first case. Also warn about -ftrivial-auto-var-init + cannot initialize the auto variable under such situation. + SEQ is the body of a switch expression. */ static void -maybe_warn_switch_unreachable (gimple_seq seq) +maybe_warn_switch_unreachable_and_auto_init (gimple_seq seq) { - if (!warn_switch_unreachable + if ((!warn_switch_unreachable && !warn_trivial_auto_var_init) /* This warning doesn't play well with Fortran when optimizations are on. */ || lang_GNU_Fortran () @@ -2093,26 +2139,36 @@ maybe_warn_switch_unreachable (gimple_seq seq) return; struct walk_stmt_info wi; - memset (&wi, 0, sizeof (wi)); - walk_gimple_seq (seq, warn_switch_unreachable_r, NULL, &wi); - gimple *stmt = (gimple *) wi.info<http://wi.info>; - if (stmt && gimple_code (stmt) != GIMPLE_LABEL) + if (warn_switch_unreachable) { - if (gimple_code (stmt) == GIMPLE_GOTO - && TREE_CODE (gimple_goto_dest (stmt)) == LABEL_DECL - && DECL_ARTIFICIAL (gimple_goto_dest (stmt))) - /* Don't warn for compiler-generated gotos. These occur - in Duff's devices, for example. */ - ; - else if ((flag_auto_var_init > AUTO_INIT_UNINITIALIZED) - && (gimple_call_internal_p (stmt, IFN_DEFERRED_INIT))) - /* Don't warn for compiler-generated initializations for - -ftrivial-auto-var-init. */ - ; - else - warning_at (gimple_location (stmt), OPT_Wswitch_unreachable, - "statement will never be executed"); + memset (&wi, 0, sizeof (wi)); + walk_gimple_seq (seq, warn_switch_unreachable_r, NULL, &wi); + gimple *stmt = (gimple *) wi.info<http://wi.info>; + + if (stmt && gimple_code (stmt) != GIMPLE_LABEL) + { + if (gimple_code (stmt) == GIMPLE_GOTO + && TREE_CODE (gimple_goto_dest (stmt)) == LABEL_DECL + && DECL_ARTIFICIAL (gimple_goto_dest (stmt))) + /* Don't warn for compiler-generated gotos. These occur + in Duff's devices, for example. */ + ; + else if ((flag_auto_var_init > AUTO_INIT_UNINITIALIZED) + && (gimple_call_internal_p (stmt, IFN_DEFERRED_INIT))) + /* Don't warn for compiler-generated initializations for + -ftrivial-auto-var-init. */ + ; + else + warning_at (gimple_location (stmt), OPT_Wswitch_unreachable, + "statement will never be executed"); + } + } + + if (warn_trivial_auto_var_init) + { + memset (&wi, 0, sizeof (wi)); + walk_gimple_seq (seq, warn_switch_unreachable_auto_init_r, NULL, &wi); } } @@ -2646,7 +2702,7 @@ gimplify_switch_expr (tree *expr_p, gimple_seq *pre_p) gimplify_stmt (&SWITCH_BODY (switch_expr), &switch_body_seq); gimplify_ctxp->in_switch_expr = old_in_switch_expr; - maybe_warn_switch_unreachable (switch_body_seq); + maybe_warn_switch_unreachable_and_auto_init (switch_body_seq); maybe_warn_implicit_fallthrough (switch_body_seq); /* Only do this for the outermost GIMPLE_SWITCH. */ if (!gimplify_ctxp->in_switch_expr) diff --git a/gcc/testsuite/gcc.dg/auto-init-pr102276-3.c b/gcc/testsuite/gcc.dg/auto-init-pr102276-3.c new file mode 100644 index 00000000000..f113f46e29d --- /dev/null +++ b/gcc/testsuite/gcc.dg/auto-init-pr102276-3.c @@ -0,0 +1,40 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -Wtrivial-auto-var-init -ftrivial-auto-var-init=zero" } */ + +int g(int *, int *); +int f() +{ + switch (0) { + int x; /* { dg-warning "cannot be initialized with" } */ + int y; /* { dg-warning "cannot be initialized with" } */ + default: + return g(&x, &y); + } +} + +int g1(int, int); +int f1() +{ + switch (0) { + int x; /* { dg-warning "cannot be initialized with" } */ + int y; /* { dg-warning "cannot be initialized with" } */ + default: + return g1(x, y); + } +} + +struct S +{ + char a; + int b; +}; +int g2(int); +int f2(int input) +{ + switch (0) { + struct S x; /* { dg-warning "cannot be initialized with" } */ + struct S y; /* { dg-warning "cannot be initialized with" } */ + default: + return g2(input) + x.b + y.b; + } +} diff --git a/gcc/testsuite/gcc.dg/auto-init-pr102276-4.c b/gcc/testsuite/gcc.dg/auto-init-pr102276-4.c new file mode 100644 index 00000000000..662e0d1182e --- /dev/null +++ b/gcc/testsuite/gcc.dg/auto-init-pr102276-4.c @@ -0,0 +1,40 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -Wtrivial-auto-var-init -ftrivial-auto-var-init=pattern" } */ + +int g(int *, int *); +int f() +{ + switch (0) { + int x; /* { dg-warning "cannot be initialized with" } */ + int y; /* { dg-warning "cannot be initialized with" } */ + default: + return g(&x, &y); + } +} + +int g1(int, int); +int f1() +{ + switch (0) { + int x; /* { dg-warning "cannot be initialized with" } */ + int y; /* { dg-warning "cannot be initialized with" } */ + default: + return g1(x, y); + } +} + +struct S +{ + char a; + int b; +}; +int g2(int); +int f2(int input) +{ + switch (0) { + struct S x; /* { dg-warning "cannot be initialized with" } */ + struct S y; /* { dg-warning "cannot be initialized with" } */ + default: + return g2(input) + x.b + y.b; + } +} -- 2.27.0
