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

…a major

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
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1 parent 73fab91 commit b620469223d3135361978668c1f5b0739e5cbaa1 @CunningBaldrick CunningBaldrick committed Sep 30, 2012
Showing with 16 additions and 7 deletions.
  1. +11 −7 lib/Analysis/Lint.cpp
  2. +5 −0 test/Other/lint.ll
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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
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@@ -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

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