add getUnderlyingObjectSize()
this is similar to getObjectSize(), but doesnt subtract the offset
tweak the BasicAA code accordingly (per PR14988)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176407 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp
index ad36cbb..4139336 100644
--- a/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/lib/Analysis/BasicAliasAnalysis.cpp
@@ -88,7 +88,7 @@
const TargetLibraryInfo &TLI,
bool RoundToAlign = false) {
uint64_t Size;
- if (getObjectSize(V, Size, &TD, &TLI, RoundToAlign))
+ if (getUnderlyingObjectSize(V, Size, &TD, &TLI, RoundToAlign))
return Size;
return AliasAnalysis::UnknownSize;
}
@@ -98,35 +98,6 @@
static bool isObjectSmallerThan(const Value *V, uint64_t Size,
const DataLayout &TD,
const TargetLibraryInfo &TLI) {
- // Note that the meanings of the "object" are slightly different in the
- // following contexts:
- // c1: llvm::getObjectSize()
- // c2: llvm.objectsize() intrinsic
- // c3: isObjectSmallerThan()
- // c1 and c2 share the same meaning; however, the meaning of "object" in c3
- // refers to the "entire object".
- //
- // Consider this example:
- // char *p = (char*)malloc(100)
- // char *q = p+80;
- //
- // In the context of c1 and c2, the "object" pointed by q refers to the
- // stretch of memory of q[0:19]. So, getObjectSize(q) should return 20.
- //
- // However, in the context of c3, the "object" refers to the chunk of memory
- // being allocated. So, the "object" has 100 bytes, and q points to the middle
- // the "object". In case q is passed to isObjectSmallerThan() as the 1st
- // parameter, before the llvm::getObjectSize() is called to get the size of
- // entire object, we should:
- // - either rewind the pointer q to the base-address of the object in
- // question (in this case rewind to p), or
- // - just give up. It is up to caller to make sure the pointer is pointing
- // to the base address the object.
- //
- // We go for 2nd option for simplicity.
- if (!isIdentifiedObject(V))
- return false;
-
// This function needs to use the aligned object size because we allow
// reads a bit past the end given sufficient alignment.
uint64_t ObjectSize = getObjectSize(V, TD, TLI, /*RoundToAlign*/true);