[Sema] add -Walloca to flag uses of `alloca`
This CL adds an optional warning to diagnose uses of the `__builtin_alloca` family of functions. The use of these functions is discouraged by many, so it seems like a good idea to allow clang to warn about it. Patch by Elaina Guan! Differential Revision: https://reviews.llvm.org/D64883 llvm-svn: 367067
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@ -2779,6 +2779,11 @@ def err_no_accessor_for_property : Error<
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def err_cannot_find_suitable_accessor : Error<
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def err_cannot_find_suitable_accessor : Error<
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"cannot find suitable %select{getter|setter}0 for property %1">;
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"cannot find suitable %select{getter|setter}0 for property %1">;
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def warn_alloca : Warning<
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"use of function %0 is discouraged; there is no way to check for failure but "
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"failure may still occur, resulting in a possibly exploitable security vulnerability">,
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InGroup<DiagGroup<"alloca">>, DefaultIgnore;
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def warn_alloca_align_alignof : Warning<
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def warn_alloca_align_alignof : Warning<
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"second argument to __builtin_alloca_with_align is supposed to be in bits">,
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"second argument to __builtin_alloca_with_align is supposed to be in bits">,
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InGroup<DiagGroup<"alloca-with-align-alignof">>;
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InGroup<DiagGroup<"alloca-with-align-alignof">>;
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@ -1179,6 +1179,10 @@ Sema::CheckBuiltinFunctionCall(FunctionDecl *FDecl, unsigned BuiltinID,
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case Builtin::BI__builtin_alloca_with_align:
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case Builtin::BI__builtin_alloca_with_align:
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if (SemaBuiltinAllocaWithAlign(TheCall))
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if (SemaBuiltinAllocaWithAlign(TheCall))
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return ExprError();
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return ExprError();
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LLVM_FALLTHROUGH;
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case Builtin::BI__builtin_alloca:
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Diag(TheCall->getBeginLoc(), diag::warn_alloca)
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<< TheCall->getDirectCallee();
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break;
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break;
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case Builtin::BI__assume:
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case Builtin::BI__assume:
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case Builtin::BI__builtin_assume:
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case Builtin::BI__builtin_assume:
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@ -0,0 +1,20 @@
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// RUN: %clang_cc1 -DSILENCE -fsyntax-only -verify -Wall %s
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// RUN: %clang_cc1 -fsyntax-only -verify -Walloca %s
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#ifdef SILENCE
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// expected-no-diagnostics
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#endif
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void test1(int a) {
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__builtin_alloca(a);
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#ifndef SILENCE
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// expected-warning@-2 {{use of function '__builtin_alloca' is discouraged; there is no way to check for failure but failure may still occur, resulting in a possibly exploitable security vulnerability}}
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#endif
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}
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void test2(int a) {
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__builtin_alloca_with_align(a, 32);
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#ifndef SILENCE
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// expected-warning@-2 {{use of function '__builtin_alloca_with_align' is discouraged; there is no way to check for failure but failure may still occur, resulting in a possibly exploitable security vulnerability}}
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#endif
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}
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