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GCC supports three flags related to overflow behavior: * `-fwrapv`: Makes signed integer overflow well-defined. * `-fwrapv-pointer`: Makes pointer overflow well-defined. * `-fno-strict-overflow`: Implies `-fwrapv -fwrapv-pointer`, making both signed integer overflow and pointer overflow well-defined. Clang currently only supports `-fno-strict-overflow` and `-fwrapv`, but not `-fwrapv-pointer`. This PR proposes to introduce `-fwrapv-pointer` and adjust the semantics of `-fwrapv` to match GCC. This allows signed integer overflow and pointer overflow to be controlled independently, while `-fno-strict-overflow` still exists to control both at the same time (and that option is consistent across GCC and Clang).
78 lines
2.3 KiB
C
78 lines
2.3 KiB
C
// RUN: %clang_cc1 -fsyntax-only -verify %s
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// RUN: %clang_cc1 -fsyntax-only -fwrapv-pointer -verify=fwrapv %s
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// fwrapv-no-diagnostics
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int add_ptr_idx_ult_ptr(const char *ptr, unsigned index) {
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return ptr + index < ptr; // expected-warning {{pointer comparison always evaluates to false}}
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}
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int add_idx_ptr_ult_ptr(const char *ptr, unsigned index) {
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return index + ptr < ptr; // expected-warning {{pointer comparison always evaluates to false}}
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}
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int ptr_ugt_add_ptr_idx(const char *ptr, unsigned index) {
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return ptr > ptr + index; // expected-warning {{pointer comparison always evaluates to false}}
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}
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int ptr_ugt_add_idx_ptr(const char *ptr, unsigned index) {
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return ptr > index + ptr; // expected-warning {{pointer comparison always evaluates to false}}
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}
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int add_ptr_idx_uge_ptr(const char *ptr, unsigned index) {
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return ptr + index >= ptr; // expected-warning {{pointer comparison always evaluates to true}}
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}
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int add_idx_ptr_uge_ptr(const char *ptr, unsigned index) {
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return index + ptr >= ptr; // expected-warning {{pointer comparison always evaluates to true}}
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}
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int ptr_ule_add_ptr_idx(const char *ptr, unsigned index) {
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return ptr <= ptr + index; // expected-warning {{pointer comparison always evaluates to true}}
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}
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int ptr_ule_add_idx_ptr(const char *ptr, unsigned index) {
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return ptr <= index + ptr; // expected-warning {{pointer comparison always evaluates to true}}
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}
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int add_ptr_idx_ult_ptr_array(unsigned index) {
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char ptr[10];
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return ptr + index < ptr; // expected-warning {{pointer comparison always evaluates to false}}
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}
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// Negative tests with wrong predicate.
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int add_ptr_idx_ule_ptr(const char *ptr, unsigned index) {
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return ptr + index <= ptr;
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}
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int add_ptr_idx_ugt_ptr(const char *ptr, unsigned index) {
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return ptr + index > ptr;
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}
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int ptr_uge_add_idx_ptr(const char *ptr, unsigned index) {
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return ptr >= index + ptr;
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}
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int ptr_ult_add_idx_ptr(const char *ptr, unsigned index) {
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return ptr < index + ptr;
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}
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// Negative test with signed index.
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int add_ptr_idx_ult_ptr_signed(const char *ptr, int index) {
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return ptr + index < ptr;
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}
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// Negative test with unrelated pointers.
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int add_ptr_idx_ult_ptr2(const char *ptr, const char *ptr2, unsigned index) {
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return ptr + index < ptr2;
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}
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// Negative test with non-pointer operands.
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int add_ptr_idx_ult_ptr_not_pointer(unsigned ptr, unsigned index) {
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return ptr + index < ptr;
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}
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