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Sema: Restrict alignment to 2**28. 

Allowing alignment past this point causes wrap around within clang.

N.B.  GCC has the same restriction.

llvm-svn: 201254
This commit is contained in:
David Majnemer 2014-02-12 20:36:10 +00:00
parent 7199fd532c
commit abecae741c
3 changed files with 9 additions and 10 deletions
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4
clang/include/clang/Basic/DiagnosticSemaKinds.td
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@ -1982,8 +1982,8 @@ def error_cannot_find_suitable_accessor : Error<
def err_attribute_aligned_not_power_of_two : Error< def err_attribute_aligned_not_power_of_two : Error<
"requested alignment is not a power of 2">; "requested alignment is not a power of 2">;
def err_attribute_aligned_greater_than_8192 : Error< def err_attribute_aligned_too_great : Error<
"requested alignment must be 8192 bytes or smaller">; "requested alignment must be %0 bytes or smaller">;
def warn_redeclaration_without_attribute_prev_attribute_ignored : Warning< def warn_redeclaration_without_attribute_prev_attribute_ignored : Warning<
"%0 redeclared without %1 attribute: previous %1 ignored">; "%0 redeclared without %1 attribute: previous %1 ignored">;
def warn_attribute_ignored : Warning<"%0 attribute ignored">, def warn_attribute_ignored : Warning<"%0 attribute ignored">,

14
clang/lib/Sema/SemaDeclAttr.cpp
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@ -2814,14 +2814,12 @@ void Sema::AddAlignedAttr(SourceRange AttrRange, Decl *D, Expr *E,
return; return;
} }
if (TmpAttr.isDeclspec()) { // Alignment calculations can wrap around if it's greater than 2**28.
// We've already verified it's a power of 2, now let's make sure it's unsigned MaxValidAlignment = TmpAttr.isDeclspec() ? 8192 : 268435456;
// 8192 or less. if (Alignment.getZExtValue() > MaxValidAlignment) {
if (Alignment.getZExtValue() > 8192) { Diag(AttrLoc, diag::err_attribute_aligned_too_great) << MaxValidAlignment
Diag(AttrLoc, diag::err_attribute_aligned_greater_than_8192) << E->getSourceRange();
<< E->getSourceRange(); return;
return;
}
} }
AlignedAttr *AA = ::new (Context) AlignedAttr(AttrRange, Context, true, AlignedAttr *AA = ::new (Context) AlignedAttr(AttrRange, Context, true,

1
clang/test/Sema/attr-aligned.c
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@ -1,6 +1,7 @@
// RUN: %clang_cc1 -triple i386-apple-darwin9 -fsyntax-only -verify %s // RUN: %clang_cc1 -triple i386-apple-darwin9 -fsyntax-only -verify %s
int x __attribute__((aligned(3))); // expected-error {{requested alignment is not a power of 2}} int x __attribute__((aligned(3))); // expected-error {{requested alignment is not a power of 2}}
int y __attribute__((aligned(1 << 29))); // expected-error {{requested alignment must be 268435456 bytes or smaller}}
// PR3254 // PR3254
short g0[3] __attribute__((aligned)); short g0[3] __attribute__((aligned));