[MemoryLocation] Support memcpy_chk in getForArgument.

[fhahn]

Summary

Similar to 9f9e8ba114ce, add support for memcyp_chk to
MemoryLocation::getForArgument.

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

[jdoerfert]

LG

[xbolva00]

llvm/lib/Analysis/MemoryLocation.cpp

263–264

Generalize

[fhahn]

llvm/lib/Analysis/MemoryLocation.cpp

263–264

Thanks, adjusted in the committed version.

llvm/lib/Analysis/MemoryLocation.cpp

MemoryLocation MemoryLocation::getForArgument(const CallBase *Call,
   if (TLI && TLI->getLibFunc(*Call, F) && TLI->has(F)) {
     switch (F) {
     case LibFunc_strcpy:
     case LibFunc_strcat:
     case LibFunc_strncat:
       assert((ArgIdx == 0 || ArgIdx == 1) && "Invalid argument index for str function");
       return MemoryLocation::getAfter(Arg, AATags);
 
-    case LibFunc_memset_chk: {
+    case LibFunc_memset_chk:
       assert(ArgIdx == 0 && "Invalid argument index for memset_chk");
+      LLVM_FALLTHROUGH;
+    case LibFunc_memcpy_chk: {
+      assert((ArgIdx == 0 || ArgIdx == 1) &&
+             "Invalid argument index for memcpy_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.
+        // memset_chk writes at most Len bytes, memcpy_chk reads/writes at most
+        // Len bytes. They may read/write less, if Len exceeds the specified max
+        // size and aborts.
         Size = LocationSize::upperBound(Len->getZExtValue());
       }
       return MemoryLocation(Arg, Size, AATags);
     }
     case LibFunc_strncpy: {
       assert((ArgIdx == 0 || ArgIdx == 1) &&
              "Invalid argument index for strncpy");
       LocationSize Size = LocationSize::afterPointer();

llvm/test/Analysis/BasicAA/libfuncs.ll

 
 declare i8* @__memcpy_chk(i8* writeonly, i8* readonly, i64, i64)
 
 define i8* @test_memcpy_chk_const_size(i8* noalias %a, i8* noalias %b, i64 %n) {
 ; CHECK-LABEL: Function: test_memcpy_chk_const_size
 ; CHECK:       Just Mod:  Ptr: i8* %a <->  %res = tail call i8* @__memcpy_chk(i8* %a, i8* %b, i64 4, i64 %n)
 ; CHECK-NEXT:  Just Mod:  Ptr: i8* %res <->  %res = tail call i8* @__memcpy_chk(i8* %a, i8* %b, i64 4, i64 %n)
 ; CHECK-NEXT:  Just Mod:  Ptr: i8* %a.gep.1 <->  %res = tail call i8* @__memcpy_chk(i8* %a, i8* %b, i64 4, i64 %n)
-; CHECK-NEXT:  Just Mod:  Ptr: i8* %a.gep.5 <->  %res = tail call i8* @__memcpy_chk(i8* %a, i8* %b, i64 4, i64 %n)
+; CHECK-NEXT:  NoModRef:  Ptr: i8* %a.gep.5 <->  %res = tail call i8* @__memcpy_chk(i8* %a, i8* %b, i64 4, i64 %n)
 ; CHECK-NEXT:  Just Ref:  Ptr: i8* %b.gep.1 <->  %res = tail call i8* @__memcpy_chk(i8* %a, i8* %b, i64 4, i64 %n)
-; CHECK-NEXT:  Just Ref:  Ptr: i8* %b.gep.5 <->  %res = tail call i8* @__memcpy_chk(i8* %a, i8* %b, i64 4, i64 %n)
+; CHECK-NEXT:  NoModRef:  Ptr: i8* %b.gep.5 <->  %res = tail call i8* @__memcpy_chk(i8* %a, i8* %b, i64 4, i64 %n)
 ;
 entry:
   load i8, i8* %a
   %res = tail call i8* @__memcpy_chk(i8* %a, i8* %b, i64 4, i64 %n)
   load i8, i8* %res
   %a.gep.1 = getelementptr i8, i8* %a, i32 1
   store i8 0, i8* %a.gep.1
   %a.gep.5 = getelementptr i8, i8* %a, i32 5