[PATCH] D107420: [sema] Disallow __builtin_mul_overflow under special condition.
Freddy, Ye via Phabricator via cfe-commits
cfe-commits at lists.llvm.org
Wed Aug 4 22:31:17 PDT 2021
FreddyYe updated this revision to Diff 364349.
FreddyYe added a comment.
update lit test, clang-format, if condition, diagnostic
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D107420/new/
https://reviews.llvm.org/D107420
Files:
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/lib/Sema/SemaChecking.cpp
clang/test/Sema/builtins-overflow.c
Index: clang/test/Sema/builtins-overflow.c
===================================================================
--- clang/test/Sema/builtins-overflow.c
+++ clang/test/Sema/builtins-overflow.c
@@ -38,4 +38,22 @@
_ExtInt(129) result;
_Bool status = __builtin_mul_overflow(x, y, &result); // expected-error {{__builtin_mul_overflow does not support signed _ExtInt operands of more than 128 bits}}
}
+ {
+ _ExtInt(128) x = 1;
+ _ExtInt(128) y = 1;
+ unsigned _ExtInt(128) result;
+ _Bool status = __builtin_mul_overflow(x, y, &result); // expected-error {{when __builtin_mul_overflow's result argument points to unsigned 128 bit integer, pls make sure input operands won't produce positive (2^127)~(2^128-1) from two negative integer value. That's not supported yet.}}
+ }
+ {
+ _ExtInt(65) x = 1;
+ _ExtInt(64) y = 1;
+ unsigned _ExtInt(128) result;
+ _Bool status = __builtin_mul_overflow(x, y, &result); // expected-error {{when __builtin_mul_overflow's result argument points to unsigned 128 bit integer, pls make sure input operands won't produce positive (2^127)~(2^128-1) from two negative integer value. That's not supported yet.}}
+ }
+ {
+ _ExtInt(64) x = 1;
+ _ExtInt(64) y = 1;
+ unsigned _ExtInt(128) result;
+ _Bool status = __builtin_mul_overflow(x, y, &result); // expected ok
+ }
}
Index: clang/lib/Sema/SemaChecking.cpp
===================================================================
--- clang/lib/Sema/SemaChecking.cpp
+++ clang/lib/Sema/SemaChecking.cpp
@@ -328,6 +328,22 @@
// Disallow signed ExtIntType args larger than 128 bits to mul function until
// we improve backend support.
if (BuiltinID == Builtin::BI__builtin_mul_overflow) {
+ const auto LeftTy = TheCall->getArg(0)->getType();
+ const auto RightTy = TheCall->getArg(1)->getType();
+ const auto ResultPointeeTy =
+ TheCall->getArg(2)->getType()->getPointeeType();
+ // Input combination below will also emit an integer value larger than
+ // 128 bits in the backend, disallow same as above.
+ if (!ResultPointeeTy->isSignedIntegerType() &&
+ S.getASTContext().getIntWidth(ResultPointeeTy) == 128 &&
+ ((LeftTy->isSignedIntegerType() ? S.getASTContext().getIntWidth(LeftTy)
+ : 0) +
+ (RightTy->isSignedIntegerType()
+ ? S.getASTContext().getIntWidth(RightTy)
+ : 0)) > 128) {
+ return S.Diag(TheCall->getArg(0)->getBeginLoc(),
+ diag::err_overflow_builtin_mul_special_condition_max_size);
+ }
for (unsigned I = 0; I < 3; ++I) {
const auto Arg = TheCall->getArg(I);
// Third argument will be a pointer.
Index: clang/include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -8348,6 +8348,10 @@
def err_overflow_builtin_ext_int_max_size : Error<
"__builtin_mul_overflow does not support signed _ExtInt operands of more "
"than %0 bits">;
+def err_overflow_builtin_mul_special_condition_max_size : Error<
+ "when __builtin_mul_overflow's result argument points to unsigned 128 bit integer, pls make sure "
+ "input operands won't produce positive (2^127)~(2^128-1) from two negative integer value. That's "
+ "not supported yet.">;
def err_atomic_load_store_uses_lib : Error<
"atomic %select{load|store}0 requires runtime support that is not "
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