Add the 'initializes' attribute langref and support (#84803)

We propose adding a new LLVM attribute,
`initializes((Lo1,Hi1),(Lo2,Hi2),...)`, which expresses the notion of
memory space (i.e., intervals, in bytes) that the argument pointing to
is initialized in the function.

Will commit the attribute inferring in the follow-up PRs.


https://discourse.llvm.org/t/rfc-llvm-new-initialized-parameter-attribute-for-improved-interprocedural-dse/77337

1 files changed, 9 insertions, 0 deletions

diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
index fe2253d..0abd5f7 100644
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -72,6 +72,7 @@
 #include "llvm/IR/Comdat.h"
 #include "llvm/IR/Constant.h"
 #include "llvm/IR/ConstantRange.h"
+#include "llvm/IR/ConstantRangeList.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/ConvergenceVerifier.h"
 #include "llvm/IR/DataLayout.h"
@@ -2059,6 +2060,14 @@ void Verifier::verifyParameterAttrs(AttributeSet Attrs, Type *Ty,
     }
   }
 
+  if (Attrs.hasAttribute(Attribute::Initializes)) {
+    auto Inits = Attrs.getAttribute(Attribute::Initializes).getInitializes();
+    Check(!Inits.empty(), "Attribute 'initializes' does not support empty list",
+          V);
+    Check(ConstantRangeList::isOrderedRanges(Inits),
+          "Attribute 'initializes' does not support unordered ranges", V);
+  }
+
   if (Attrs.hasAttribute(Attribute::NoFPClass)) {
     uint64_t Val = Attrs.getAttribute(Attribute::NoFPClass).getValueAsInt();
     Check(Val != 0, "Attribute 'nofpclass' must have at least one test bit set",