maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

[MemoryLocation] Support memset_chk in getForArgument. 

The size argument for memset_chk is an upper bound for the size of the
pointer argument. memset_chk may write less than the specified length,
if it exceeds the specified max size and aborts.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D114870
This commit is contained in:
Florian Hahn 2021-12-02 13:45:58 +00:00
parent a692c5492a
commit 9f9e8ba114
No known key found for this signature in database
GPG Key ID: EEF712BB5E80EBBA
2 changed files with 11 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
llvm/lib/Analysis/MemoryLocation.cpp
View File

@ -213,6 +213,16 @@ MemoryLocation MemoryLocation::getForArgument(const CallBase *Call,
LibFunc F;
if (TLI && TLI->getLibFunc(*Call, F) && TLI->has(F)) {
switch (F) {
case LibFunc_memset_chk: {
assert(ArgIdx == 0 && "Invalid argument index for memset_chk");
LocationSize Size = LocationSize::afterPointer();
if (const auto *Len = dyn_cast<ConstantInt>(Call->getArgOperand(2))) {
// memset_chk writes at most Len bytes. It may write less, if Len
// exceeds the specified max size and aborts.
Size = LocationSize::upperBound(Len->getZExtValue());
}
return MemoryLocation(Arg, Size, AATags);
}
case LibFunc_memset_pattern16:
assert((ArgIdx == 0 || ArgIdx == 1) &&
"Invalid argument index for memset_pattern16");

2
llvm/test/Analysis/BasicAA/libfuncs.ll
View File

@ -183,7 +183,7 @@ define i8* @test_memset_chk_const_size(i8* noalias %a, i64 %n) {
; CHECK: Just Mod (MustAlias): Ptr: i8* %a <-> %res = tail call i8* @__memset_chk(i8* %a, i32 0, i64 4, i64 %n)
; CHECK-NEXT: Just Mod: Ptr: i8* %res <-> %res = tail call i8* @__memset_chk(i8* %a, i32 0, i64 4, i64 %n)
; CHECK-NEXT: Just Mod: Ptr: i8* %a.gep.1 <-> %res = tail call i8* @__memset_chk(i8* %a, i32 0, i64 4, i64 %n)
; CHECK-NEXT: Just Mod: Ptr: i8* %a.gep.5 <-> %res = tail call i8* @__memset_chk(i8* %a, i32 0, i64 4, i64 %n)
; CHECK-NEXT: NoModRef: Ptr: i8* %a.gep.5 <-> %res = tail call i8* @__memset_chk(i8* %a, i32 0, i64 4, i64 %n)
;
entry:
%res = tail call i8* @__memset_chk(i8* %a, i32 0, i64 4, i64 %n)