[PATCH] D148202: [LangRef][Local] dereferenceable metadata violation is UB

[Nikita Popov via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rGe4251fc6bb0d: [LangRef][Local] dereferenceable metadata violation is UB (authored by nikic).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D148202/new/

https://reviews.llvm.org/D148202

Files:
  llvm/docs/LangRef.rst
  llvm/lib/Transforms/Utils/Local.cpp
  llvm/test/Transforms/GVN/metadata.ll


Index: llvm/test/Transforms/GVN/metadata.ll
===================================================================
--- llvm/test/Transforms/GVN/metadata.ll
+++ llvm/test/Transforms/GVN/metadata.ll
@@ -138,7 +138,7 @@
 define void @load_dereferenceable_dominating(ptr %p) {
 ; CHECK-LABEL: define void @load_dereferenceable_dominating
 ; CHECK-SAME: (ptr [[P:%.*]]) {
-; CHECK-NEXT:    [[A:%.*]] = load ptr, ptr [[P]], align 8
+; CHECK-NEXT:    [[A:%.*]] = load ptr, ptr [[P]], align 8, !dereferenceable !7
 ; CHECK-NEXT:    call void @use.ptr(ptr [[A]])
 ; CHECK-NEXT:    call void @use.ptr(ptr [[A]])
 ; CHECK-NEXT:    ret void
Index: llvm/lib/Transforms/Utils/Local.cpp
===================================================================
--- llvm/lib/Transforms/Utils/Local.cpp
+++ llvm/lib/Transforms/Utils/Local.cpp
@@ -2701,8 +2701,9 @@
         break;
       case LLVMContext::MD_dereferenceable:
       case LLVMContext::MD_dereferenceable_or_null:
-        K->setMetadata(Kind,
-          MDNode::getMostGenericAlignmentOrDereferenceable(JMD, KMD));
+        if (DoesKMove)
+          K->setMetadata(Kind,
+            MDNode::getMostGenericAlignmentOrDereferenceable(JMD, KMD));
         break;
       case LLVMContext::MD_preserve_access_index:
         // Preserve !preserve.access.index in K.
Index: llvm/docs/LangRef.rst
===================================================================
--- llvm/docs/LangRef.rst
+++ llvm/docs/LangRef.rst
@@ -6656,7 +6656,8 @@
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 The existence of the ``!dereferenceable`` metadata on the instruction
-tells the optimizer that the value loaded is known to be dereferenceable.
+tells the optimizer that the value loaded is known to be dereferenceable,
+otherwise the behavior is undefined.
 The number of bytes known to be dereferenceable is specified by the integer
 value in the metadata node. This is analogous to the ''dereferenceable''
 attribute on parameters and return values.
@@ -6668,7 +6669,7 @@
 
 The existence of the ``!dereferenceable_or_null`` metadata on the
 instruction tells the optimizer that the value loaded is known to be either
-dereferenceable or null.
+dereferenceable or null, otherwise the behavior is undefined.
 The number of bytes known to be dereferenceable is specified by the integer
 value in the metadata node. This is analogous to the ''dereferenceable_or_null''
 attribute on parameters and return values.


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