[BuildLibCalls] Add argmemonly, writeonly, nounwind to memset_chk.

[fhahn]

Summary

The memset_chk library function should match memset's attributes with
respect of memory effects (argmemonly, writeonly). It also does not
raise exceptions. It may not return, in case it aborts the program.

[xbolva00]

llvm/lib/Transforms/Utils/BuildLibCalls.cpp

464

Maybe also improve this?

[fhahn]

llvm/lib/Transforms/Utils/BuildLibCalls.cpp

464

Im planning on a similar treatment for memcpy_chk if the memset_chk changes make sense :)

[efriedma]

LGTM

[fhahn]

llvm/lib/Transforms/Utils/BuildLibCalls.cpp

464

I put up D114863

llvm/lib/Transforms/Utils/BuildLibCalls.cpp

case LibFunc_memccpy:
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotAlias(F, 0);
     Changed |= setOnlyWritesMemory(F, 0);
     Changed |= setDoesNotAlias(F, 1);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setOnlyReadsMemory(F, 1);
     return Changed;
   case LibFunc_memcpy_chk:
     Changed |= setDoesNotThrow(F);
     return Changed;
   case LibFunc_memalign:
     Changed |= setOnlyAccessesInaccessibleMemory(F);
     Changed |= setRetNoUndef(F);
     Changed |= setDoesNotThrow(F);
     Changed |= setRetDoesNotAlias(F);
     Changed |= setWillReturn(F);
bool llvm::inferLibFuncAttributes(Function &F, const TargetLibraryInfo &TLI) {
   case LibFunc_memset_pattern16:
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setOnlyWritesMemory(F, 0);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setOnlyReadsMemory(F, 1);
     return Changed;
   case LibFunc_memset:
-    Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setWillReturn(F);
-    Changed |= setDoesNotThrow(F);
+    LLVM_FALLTHROUGH;
+  case LibFunc_memset_chk:
+    Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setOnlyWritesMemory(F, 0);
+    Changed |= setDoesNotThrow(F);
     return Changed;
   // int __nvvm_reflect(const char *)
   case LibFunc_nvvm_reflect:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotAccessMemory(F);
     Changed |= setDoesNotThrow(F);
     return Changed;
   case LibFunc_ldexp:

llvm/test/Transforms/InferFunctionAttrs/annotate.ll

 declare i8* @mempcpy(i8*, i8*, i64)
 
 ; CHECK: declare i8* @memmove(i8* returned writeonly, i8* nocapture readonly, i64) [[ARGMEMONLY_NOFREE_NOUNWIND_WILLRETURN]]
 declare i8* @memmove(i8*, i8*, i64)
 
 ; CHECK: declare i8* @memset(i8* writeonly, i32, i64) [[ARGMEMONLY_NOFREE_NOUNWIND_WILLRETURN:#[0-9]+]]
 declare i8* @memset(i8*, i32, i64)
 
-; CHECK: declare i8* @__memset_chk(i8*, i32, i64, i64) [[NOFREE:#[0-9]+]]
+; CHECK: declare i8* @__memset_chk(i8* writeonly, i32, i64, i64) [[ARGMEMONLY_NOFREE_NOUNWIND:#[0-9]+]]
 declare i8* @__memset_chk(i8*, i32, i64, i64)
 
 ; CHECK: declare noundef i32 @mkdir(i8* nocapture noundef readonly, i16 noundef zeroext) [[NOFREE_NOUNWIND]]
 declare i32 @mkdir(i8*, i16 zeroext)
 
 ; CHECK: declare noundef i64 @mktime(%opaque* nocapture noundef) [[NOFREE_NOUNWIND_WILLRETURN]]
 declare i64 @mktime(%opaque*)
 

 declare double @nearbyint(double)
 
 ; CHECK: declare float @nearbyintf(float) [[NOFREE_NOUNWIND_WILLRETURN]]
 declare float @nearbyintf(float)
 
 ; CHECK: declare x86_fp80 @nearbyintl(x86_fp80) [[NOFREE_NOUNWIND_WILLRETURN]]
 declare x86_fp80 @nearbyintl(x86_fp80)
 
-; CHECK: declare noundef i32 @open(i8* nocapture noundef readonly, i32 noundef, ...) [[NOFREE]]
+; CHECK: declare noundef i32 @open(i8* nocapture noundef readonly, i32 noundef, ...) [[NOFREE:#[0-9]+]]
 declare i32 @open(i8*, i32, ...)
 
 ; CHECK-LINUX: declare noundef i32 @open64(i8* nocapture noundef readonly, i32 noundef, ...) [[NOFREE]]
 declare i32 @open64(i8*, i32, ...)
 
 ; CHECK: declare noalias noundef %opaque* @opendir(i8* nocapture noundef readonly) [[NOFREE_NOUNWIND]]
 declare %opaque* @opendir(i8*)
 

 ; CHECK-DAG: attributes [[ARGMEMONLY_NOFREE_NOUNWIND_WILLRETURN]] = { argmemonly mustprogress nofree nounwind willreturn }
 ; CHECK-DAG: attributes [[NOFREE_NOUNWIND_READONLY]] = { nofree nounwind readonly }
 ; CHECK-DAG: attributes [[INACCESSIBLEMEMORARGMEMONLY_NOUNWIND_WILLRETURN]] = { inaccessiblemem_or_argmemonly mustprogress nounwind willreturn }
 ; CHECK-DAG: attributes [[NOFREE_WILLRETURN]] = { mustprogress nofree willreturn }
 ; CHECK-DAG: attributes [[ARGMEMONLY_NOFREE_NOUNWIND_READONLY_WILLRETURN]] = { argmemonly mustprogress nofree nounwind readonly willreturn }
 ; CHECK-DAG: attributes [[NOFREE]] = { nofree }
 ; CHECK-DAG: attributes [[WILLRETURN]] = { mustprogress willreturn }
 ; CHECK-DAG: attributes [[INACCESSIBLEMEMORARGONLY_NOFREE_NOUNWIND_WILLRETURN]]  = { inaccessiblemem_or_argmemonly mustprogress nofree nounwind willreturn }
+; CHECK-DAG: attributes [[ARGMEMONLY_NOFREE_NOUNWIND]] = { argmemonly nofree nounwind }
 
 ; CHECK-DARWIN-DAG: attributes [[ARGMEMONLY_NOFREE]] = { argmemonly nofree }
 ; CHECK-NVPTX-DAG: attributes [[NOFREE_NOUNWIND_READNONE]] = { nofree nosync nounwind readnone }