From 16137fbb9256ef365dd498d39024eb33de1a4cd8 Mon Sep 17 00:00:00 2001 From: Martin Sebor Date: Fri, 19 Nov 2021 09:44:31 -0700 Subject: [PATCH] Restore ancient -Waddress for weak symbols [PR33925]. Resolves: PR c/33925 - gcc -Waddress lost some useful warnings PR c/102867 - -Waddress from macro expansion in readelf.c gcc/c-family/ChangeLog: PR c++/33925 PR c/102867 * c-common.c (decl_with_nonnull_addr_p): Call maybe_nonzero_address and improve handling tof defined symbols. gcc/c/ChangeLog: PR c++/33925 PR c/102867 * c-typeck.c (maybe_warn_for_null_address): Suppress warnings for code resulting from macro expansion. gcc/cp/ChangeLog: PR c++/33925 PR c/102867 * typeck.c (warn_for_null_address): Suppress warnings for code resulting from macro expansion. gcc/ChangeLog: PR c++/33925 PR c/102867 * doc/invoke.texi (-Waddress): Update. gcc/testsuite/ChangeLog: PR c++/33925 PR c/102867 * g++.dg/warn/Walways-true-2.C: Adjust to avoid a valid warning. * c-c++-common/Waddress-5.c: New test. * c-c++-common/Waddress-6.c: New test. * g++.dg/warn/Waddress-7.C: New test. * gcc.dg/Walways-true-2.c: Adjust to avoid a valid warning. * gcc.dg/weak/weak-3.c: Expect a warning. --- gcc/c-family/c-common.c | 39 +++++- gcc/c/c-typeck.c | 5 +- gcc/cp/typeck.c | 2 + gcc/doc/invoke.texi | 2 + gcc/testsuite/c-c++-common/Waddress-5.c | 133 +++++++++++++++++++++ gcc/testsuite/c-c++-common/Waddress-6.c | 32 +++++ gcc/testsuite/g++.dg/warn/Waddress-7.C | 76 ++++++++++++ gcc/testsuite/g++.dg/warn/Walways-true-2.C | 2 +- gcc/testsuite/gcc.dg/Walways-true-2.c | 2 +- gcc/testsuite/gcc.dg/weak/weak-3.c | 6 +- 10 files changed, 288 insertions(+), 11 deletions(-) create mode 100644 gcc/testsuite/c-c++-common/Waddress-5.c create mode 100644 gcc/testsuite/c-c++-common/Waddress-6.c create mode 100644 gcc/testsuite/g++.dg/warn/Waddress-7.C diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c index 86c007f53def..a25d59fa77b0 100644 --- a/gcc/c-family/c-common.c +++ b/gcc/c-family/c-common.c @@ -3413,16 +3413,43 @@ c_wrap_maybe_const (tree expr, bool non_const) /* Return whether EXPR is a declaration whose address can never be NULL. The address of the first struct member could be NULL only if it were - accessed through a NULL pointer, and such an access would be invalid. */ + accessed through a NULL pointer, and such an access would be invalid. + The address of a weak symbol may be null unless it has a definition. */ bool decl_with_nonnull_addr_p (const_tree expr) { - return (DECL_P (expr) - && (TREE_CODE (expr) == FIELD_DECL - || TREE_CODE (expr) == PARM_DECL - || TREE_CODE (expr) == LABEL_DECL - || !DECL_WEAK (expr))); + if (!DECL_P (expr)) + return false; + + if (TREE_CODE (expr) == FIELD_DECL + || TREE_CODE (expr) == PARM_DECL + || TREE_CODE (expr) == LABEL_DECL) + return true; + + if (!VAR_OR_FUNCTION_DECL_P (expr)) + return false; + + if (!DECL_WEAK (expr)) + /* Ordinary (non-weak) symbols have nonnull addresses. */ + return true; + + if (DECL_INITIAL (expr) && DECL_INITIAL (expr) != error_mark_node) + /* Initialized weak symbols have nonnull addresses. */ + return true; + + if (DECL_EXTERNAL (expr) || !TREE_STATIC (expr)) + /* Uninitialized extern weak symbols and weak symbols with no + allocated storage might have a null address. */ + return false; + + tree attribs = DECL_ATTRIBUTES (expr); + if (lookup_attribute ("weakref", attribs)) + /* Weakref symbols might have a null address unless their referent + is known not to. Don't bother following weakref targets here. */ + return false; + + return true; } /* Prepare expr to be an argument of a TRUTH_NOT_EXPR, diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c index 782414f8c8cb..50d701047661 100644 --- a/gcc/c/c-typeck.c +++ b/gcc/c/c-typeck.c @@ -11588,7 +11588,10 @@ build_vec_cmp (tree_code code, tree type, static void maybe_warn_for_null_address (location_t loc, tree op, tree_code code) { - if (!warn_address || warning_suppressed_p (op, OPT_Waddress)) + /* Prevent warnings issued for macro expansion. */ + if (!warn_address + || warning_suppressed_p (op, OPT_Waddress) + || from_macro_expansion_at (loc)) return; if (TREE_CODE (op) == NOP_EXPR) diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c index cb20329ceb57..58919aaf13e9 100644 --- a/gcc/cp/typeck.c +++ b/gcc/cp/typeck.c @@ -4594,9 +4594,11 @@ build_vec_cmp (tree_code code, tree type, static void warn_for_null_address (location_t location, tree op, tsubst_flags_t complain) { + /* Prevent warnings issued for macro expansion. */ if (!warn_address || (complain & tf_warning) == 0 || c_inhibit_evaluation_warnings != 0 + || from_macro_expansion_at (location) || warning_suppressed_p (op, OPT_Waddress)) return; diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index 49c8befd58a4..11ef79703787 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -8689,6 +8689,8 @@ suppressed by casting the pointer operand to an integer type such as @code{inptr_t} or @code{uinptr_t}. Comparisons against string literals result in unspecified behavior and are not portable, and suggest the intent was to call @code{strcmp}. +The warning is suppressed if the suspicious expression is the result +of macro expansion. @option{-Waddress} warning is enabled by @option{-Wall}. @item -Wno-address-of-packed-member diff --git a/gcc/testsuite/c-c++-common/Waddress-5.c b/gcc/testsuite/c-c++-common/Waddress-5.c new file mode 100644 index 000000000000..5d63c7dae7c9 --- /dev/null +++ b/gcc/testsuite/c-c++-common/Waddress-5.c @@ -0,0 +1,133 @@ +/* PR c/33925 - missing -Waddress with the address of an inline function + { dg-do compile } + { dg-options "-Wall" } + { dg-require-weak "" } */ + +extern inline int eifn (void); +extern inline int eifn_def (void) { return 0; } + +static inline int sifn (void); +static inline int sifn_def (void) { return 0; } + +inline int ifn (void); +inline int ifn_def (void) { return 0; } + +extern __attribute__ ((weak)) int ewfn (void); +extern __attribute__ ((weak)) int ewfn_def (void) { return 0; } + +__attribute__ ((weak)) int wfn (void); +__attribute__ ((weak)) int wfn_def (void) { return 0; } + +static __attribute__((weakref ("ewfn"))) int swrfn (void); + +void test_function_eqz (int *p) +{ + *p++ = eifn == 0; // { dg-warning "-Waddress" } + *p++ = eifn_def == 0; // { dg-warning "-Waddress" } + *p++ = sifn == 0; // { dg-warning "-Waddress" } + *p++ = sifn_def == 0; // { dg-warning "-Waddress" } + *p++ = ifn == 0; // { dg-warning "-Waddress" } + *p++ = ifn_def == 0; // { dg-warning "-Waddress" } + *p++ = ewfn == 0; + *p++ = ewfn_def == 0; // { dg-warning "-Waddress" } + *p++ = wfn == 0; + *p++ = wfn_def == 0; // { dg-warning "-Waddress" } + *p++ = swrfn == 0; +} + + +int test_function_if (int i) +{ + if (eifn) // { dg-warning "-Waddress" } + i++; + if (eifn_def) // { dg-warning "-Waddress" } + i++; + if (sifn) // { dg-warning "-Waddress" } + i++; + if (sifn_def) // { dg-warning "-Waddress" } + i++; + if (ifn) // { dg-warning "-Waddress" } + i++; + if (ifn_def) // { dg-warning "-Waddress" } + i++; + if (ewfn) + i++; + if (ewfn_def) // { dg-warning "-Waddress" } + i++; + if (wfn) + i++; + if(wfn_def) // { dg-warning "-Waddress" } + i++; + if (swrfn) + i++; + return i; +} + + +extern int ei; +extern int ei_def = 1; + +static int si; +static int si_def = 1; + +int i; +int i_def = 1; + +extern __attribute__ ((weak)) int ewi; // declaration (may be null) +extern __attribute__ ((weak)) int ewi_def = 1; + +__attribute__ ((weak)) int wi; // definition (cannot be bull) +__attribute__ ((weak)) int wi_def = 1; + +static __attribute__((weakref ("ewi"))) int swri; + +void test_scalar (int *p) +{ + *p++ = &ei == 0; // { dg-warning "-Waddress" } + *p++ = &ei_def == 0; // { dg-warning "-Waddress" } + *p++ = &si == 0; // { dg-warning "-Waddress" } + *p++ = &si_def == 0; // { dg-warning "-Waddress" } + *p++ = &i == 0; // { dg-warning "-Waddress" } + *p++ = &i_def == 0; // { dg-warning "-Waddress" } + *p++ = &ewi == 0; + *p++ = &ewi_def == 0; // { dg-warning "-Waddress" } + *p++ = &wi == 0; // { dg-warning "-Waddress" } + *p++ = &wi_def == 0; // { dg-warning "-Waddress" } + *p++ = &swri == 0; +} + + +extern int eia[]; +extern int eia_def[] = { 1 }; + +static int sia[1]; +static int sia_def[1] = { 1 }; + +int ia[1]; +int ia_def[] = { 1 }; + +extern __attribute__ ((weak)) int ewia[]; +extern __attribute__ ((weak)) int ewia_def[] = { 1 }; + +__attribute__ ((weak)) int wia[1]; // definition (cannot be null) +__attribute__ ((weak)) int wia_def[] = { 1 }; + +static __attribute__((weakref ("ewia"))) int swria[1]; + +void test_array (int *p) +{ + *p++ = eia == 0; // { dg-warning "-Waddress" } + *p++ = eia_def == 0; // { dg-warning "-Waddress" } + *p++ = sia == 0; // { dg-warning "-Waddress" } + *p++ = sia_def == 0; // { dg-warning "-Waddress" } + *p++ = ia == 0; // { dg-warning "-Waddress" } + *p++ = ia_def == 0; // { dg-warning "-Waddress" } + *p++ = ewia == 0; + *p++ = ewia_def == 0; // { dg-warning "-Waddress" } + *p++ = wia == 0; // { dg-warning "-Waddress" } + *p++ = wia_def == 0; // { dg-warning "-Waddress" } + *p++ = swria == 0; +} + +/* { dg-prune-output "never defined" } + { dg-prune-output "initialized and declared 'extern'" } */ diff --git a/gcc/testsuite/c-c++-common/Waddress-6.c b/gcc/testsuite/c-c++-common/Waddress-6.c new file mode 100644 index 000000000000..e66e6e4a0b0b --- /dev/null +++ b/gcc/testsuite/c-c++-common/Waddress-6.c @@ -0,0 +1,32 @@ +/* PR c/102867 - -Waddress from macro expansion in readelf.c + { dg-do compile } + { dg-options "-Wall" } */ + +#define F(x) ((&x) != 0) + +int warn_nomacro (int *p, int i) +{ + return &p[i] != 0; // { dg-warning "-Waddress" } +} + +int nowarn_macro_expansion (int *p, int i) +{ + // Verify that -Waddress isn't issued for code from macro expansion. + return F (p[i]); // { dg-bogus "-Waddress" } +} + +#define G(x, i) ((&x) + i) + +int warn_function_macro_expansion (int *p, int i) +{ + /* Verify that -Waddress is issued for code involving macro expansion + where the comparison takes place outside the macro. */ + return G (*p, i) != 0; // { dg-warning "-Waddress" } +} + +#define malloc __builtin_malloc + +int warn_object_macro_expansion (int *p, int i) +{ + return malloc != 0; // { dg-warning "-Waddress" } +} diff --git a/gcc/testsuite/g++.dg/warn/Waddress-7.C b/gcc/testsuite/g++.dg/warn/Waddress-7.C new file mode 100644 index 000000000000..efdafa50cd19 --- /dev/null +++ b/gcc/testsuite/g++.dg/warn/Waddress-7.C @@ -0,0 +1,76 @@ +/* PR c/33925 - missing -Waddress with the address of an inline function + { dg-do compile } + { dg-options "-Wall" } */ + +struct A +{ + int mf (); + int mf_def () { return 0; } + + static int smf (); + static int smf_def () { return 0; } + + int mi; + static int smi; + static int smi_def; + + __attribute__ ((weak)) static int wsmi; + __attribute__ ((weak)) static int wsmi_def; + + int mia[]; + static int smia[]; + static int smia_def[]; + + __attribute__ ((weak)) static int wsmia[]; + __attribute__ ((weak)) static int wsmia_def[]; + + void test_waddress (bool*); +}; + + +/* __attribute__ ((weak)) static */ int A::smi_def = 0; +/* __attribute__ ((weak)) static */ int A::smia_def[] = { 0 }; + +/* __attribute__ ((weak)) static */ int A::wsmi_def = 0; +/* __attribute__ ((weak)) static */ int A::wsmia_def[] = { 0 }; + + + +void A::test_waddress (bool *p) +{ + if (mf) // { dg-error "cannot convert" } + p++; + if (mf_def) // { dg-error "cannot convert" } + p++; + + if (smf) // { dg-warning "-Waddress" } + p++; + if (smf_def) // { dg-warning "-Waddress" } + p++; + + if (&mi) // { dg-warning "-Waddress" } + p++; + if (&smi) // { dg-warning "-Waddress" } + p++; + if (&smi_def) // { dg-warning "-Waddress" } + p++; + + if (&wsmi) + p++; + + if (&wsmi_def) // { dg-warning "-Waddress" } + p++; + + if (mia) // { dg-warning "-Waddress" } + p++; + if (smia) // { dg-warning "-Waddress" } + p++; + if (smia_def) // { dg-warning "-Waddress" } + p++; + + if (wsmia) + p++; + + if (wsmia_def) // { dg-warning "-Waddress" } + p++; +} diff --git a/gcc/testsuite/g++.dg/warn/Walways-true-2.C b/gcc/testsuite/g++.dg/warn/Walways-true-2.C index 29a80e5c1132..e951e95b3363 100644 --- a/gcc/testsuite/g++.dg/warn/Walways-true-2.C +++ b/gcc/testsuite/g++.dg/warn/Walways-true-2.C @@ -9,7 +9,7 @@ extern int foo (int) __attribute__ ((weak)); -int i __attribute__ ((weak)); +extern int i __attribute__ ((weak)); void bar (int a) diff --git a/gcc/testsuite/gcc.dg/Walways-true-2.c b/gcc/testsuite/gcc.dg/Walways-true-2.c index 7f0bb7b10b9b..ae3262b6876b 100644 --- a/gcc/testsuite/gcc.dg/Walways-true-2.c +++ b/gcc/testsuite/gcc.dg/Walways-true-2.c @@ -9,7 +9,7 @@ extern int foo (int) __attribute__ ((weak)); -int i __attribute__ ((weak)); +extern int i __attribute__ ((weak)); void bar (int a) diff --git a/gcc/testsuite/gcc.dg/weak/weak-3.c b/gcc/testsuite/gcc.dg/weak/weak-3.c index a719848c935a..5fdf029cf357 100644 --- a/gcc/testsuite/gcc.dg/weak/weak-3.c +++ b/gcc/testsuite/gcc.dg/weak/weak-3.c @@ -55,7 +55,7 @@ void * foo1e (void) extern void * ffoo1f (void); void * foo1f (void) { - if (ffoo1f) /* { dg-warning "" } */ + if (ffoo1f) /* { dg-warning "-Waddress" } */ ffoo1f (); return 0; } @@ -68,7 +68,9 @@ void * ffoox1g (void) { return (void *)0; } extern void * ffoo1g (void) __attribute__((weak, alias ("ffoox1g"))); void * foo1g (void) { - if (ffoo1g) + /* ffoo1g is a weak alias for a symbol defined in this file, expect + a -Waddress for the test (which is folded to true). */ + if (ffoo1g) // { dg-warning "-Waddress" } ffoo1g (); return 0; } -- 2.39.2