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Ignore apparent buffer overruns on external or weak globals. This is a major

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source of false positives due to globals being declared in a header with some
kind of incomplete (small) type, but the actual definition being bigger.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@164912 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Duncan Sands 2012-09-30 07:30:10 +00:00
parent 73fab91f2c
commit b620469223
2 changed files with 16 additions and 7 deletions
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18
lib/Analysis/Lint.cpp
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@ -430,13 +430,17 @@ void Lint::visitMemoryReference(Instruction &I,
BaseAlign = AI->getAlignment();
if (BaseAlign == 0 && ATy->isSized())
BaseAlign = TD->getABITypeAlignment(ATy);
} else if (GlobalValue *GV = dyn_cast<GlobalVariable>(Base)) {
Type *GTy = GV->getType()->getElementType();
if (GTy->isSized())
BaseSize = TD->getTypeAllocSize(GTy);
BaseAlign = GV->getAlignment();
if (BaseAlign == 0 && GTy->isSized())
BaseAlign = TD->getABITypeAlignment(GTy);
} else if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Base)) {
// If the global may be defined differently in another compilation unit
// then don't warn about funky memory accesses.
if (GV->hasDefinitiveInitializer()) {
Type *GTy = GV->getType()->getElementType();
if (GTy->isSized())
BaseSize = TD->getTypeAllocSize(GTy);
BaseAlign = GV->getAlignment();
if (BaseAlign == 0 && GTy->isSized())
BaseAlign = TD->getABITypeAlignment(GTy);
}
}
// Accesses from before the start or after the end of the object are not

5
test/Other/lint.ll
View File

@ -9,6 +9,7 @@ declare void @has_noaliases(i32* noalias %p, i32* %q)
declare void @one_arg(i32)
@CG = constant i32 7
@E = external global i8
define i32 @foo() noreturn {
%buf = alloca i8
@ -100,6 +101,10 @@ next:
ret i32 0
foo:
; CHECK-NOT: Undefined behavior: Buffer overflow
; CHECK-NOT: Memory reference address is misaligned
%e = bitcast i8* @E to i64*
store i64 0, i64* %e
%z = add i32 0, 0
; CHECK: unreachable immediately preceded by instruction without side effects
unreachable