[PATCH] D89050: Add support for !noundef metatdata on loads

[Juneyoung Lee via Phabricator via llvm-commits]

aqjune updated this revision to Diff 298802.
aqjune added a comment.

Remove .rej


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D89050/new/

https://reviews.llvm.org/D89050

Files:
  llvm/docs/LangRef.rst
  llvm/include/llvm/IR/FixedMetadataKinds.def
  llvm/lib/Analysis/ValueTracking.cpp
  llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
  llvm/test/Transforms/InstSimplify/freeze-noundef.ll


Index: llvm/test/Transforms/InstSimplify/freeze-noundef.ll
===================================================================
--- llvm/test/Transforms/InstSimplify/freeze-noundef.ll
+++ llvm/test/Transforms/InstSimplify/freeze-noundef.ll
@@ -104,3 +104,23 @@
   %f = freeze i1 %y
   ret i1 %f
 }
+
+define i32 @noundef_metadata(i32* %p) {
+; CHECK-LABEL: @noundef_metadata(
+; CHECK-NEXT:    [[V:%.*]] = load i32, i32* [[P:%.*]], align 4, !noundef !0
+; CHECK-NEXT:    ret i32 [[V]]
+;
+  %v = load i32, i32* %p, !noundef !{}
+  %v.fr = freeze i32 %v
+  ret i32 %v.fr
+}
+
+define {i8, i32} @noundef_metadata2({i8, i32}* %p) {
+; CHECK-LABEL: @noundef_metadata2(
+; CHECK-NEXT:    [[V:%.*]] = load { i8, i32 }, { i8, i32 }* [[P:%.*]], align 4, !noundef !0
+; CHECK-NEXT:    ret { i8, i32 } [[V]]
+;
+  %v = load {i8, i32}, {i8, i32}* %p, !noundef !{}
+  %v.fr = freeze {i8, i32} %v
+  ret {i8, i32} %v.fr
+}
Index: llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -522,6 +522,7 @@
       break;
     case LLVMContext::MD_invariant_load:
     case LLVMContext::MD_nonnull:
+    case LLVMContext::MD_noundef:
     case LLVMContext::MD_range:
     case LLVMContext::MD_align:
     case LLVMContext::MD_dereferenceable:
Index: llvm/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/lib/Analysis/ValueTracking.cpp
+++ llvm/lib/Analysis/ValueTracking.cpp
@@ -4892,6 +4892,10 @@
       return true;
   }
 
+  if (auto *I = dyn_cast<LoadInst>(V))
+    if (I->getMetadata(LLVMContext::MD_noundef))
+      return true;
+
   if (programUndefinedIfUndefOrPoison(V, PoisonOnly))
     return true;
 
Index: llvm/include/llvm/IR/FixedMetadataKinds.def
===================================================================
--- llvm/include/llvm/IR/FixedMetadataKinds.def
+++ llvm/include/llvm/IR/FixedMetadataKinds.def
@@ -41,3 +41,4 @@
 LLVM_FIXED_MD_KIND(MD_preserve_access_index, "llvm.preserve.access.index", 27)
 LLVM_FIXED_MD_KIND(MD_misexpect, "misexpect", 28)
 LLVM_FIXED_MD_KIND(MD_vcall_visibility, "vcall_visibility", 29)
+LLVM_FIXED_MD_KIND(MD_noundef, "noundef", 30)
\ No newline at end of file
Index: llvm/docs/LangRef.rst
===================================================================
--- llvm/docs/LangRef.rst
+++ llvm/docs/LangRef.rst
@@ -9271,6 +9271,12 @@
 This metadata can only be applied to loads of a pointer type. If the returned
 value is not appropriately aligned at runtime, the behavior is undefined.
 
+The optional ``!noundef`` metadata must reference a single metadata name
+``<empty_node>`` corresponding to a node with no entries. The existence of
+``!noundef`` metadata on the instruction tells the optimizer that the value
+loaded is known to be :ref:`well defined <_welldefinedvalues>`.
+If the value isn't well defined, the behavior is undefined.
+
 Semantics:
 """"""""""
 


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