llvm-reduce: Try to preserve instruction metadata as argument attributes (#133557)

Fixes #131825

Author: arsenm

llvm/include/llvm/IR/Attributes.h

@@ -42,6 +42,7 @@ class ConstantRangeList;
 class FoldingSetNodeID;
 class Function;
 class LLVMContext;
+class Instruction;
 class Type;
 class raw_ostream;
 enum FPClassTest : unsigned;
@@ -1285,6 +1286,11 @@ class AttrBuilder {
   /// Add initializes attribute.
   AttrBuilder &addInitializesAttr(const ConstantRangeList &CRL);
 
+  /// Add 0 or more parameter attributes which are equivalent to metadata
+  /// attached to \p I. e.g. !align -> align. This assumes the argument type is
+  /// the same as the original instruction and the attribute is compatible.
+  AttrBuilder &addFromEquivalentMetadata(const Instruction &I);
+
   ArrayRef<Attribute> attrs() const { return Attrs; }
 
   bool operator==(const AttrBuilder &B) const;

llvm/lib/IR/Attributes.cpp

@@ -2291,6 +2291,38 @@ AttrBuilder &AttrBuilder::addInitializesAttr(const ConstantRangeList &CRL) {
   return addConstantRangeListAttr(Attribute::Initializes, CRL.rangesRef());
 }
 
+AttrBuilder &AttrBuilder::addFromEquivalentMetadata(const Instruction &I) {
+  if (const MDNode *NonNull = I.getMetadata(LLVMContext::MD_nonnull))
+    addAttribute(Attribute::NonNull);
+
+  if (const MDNode *NoUndef = I.getMetadata(LLVMContext::MD_noundef))
+    addAttribute(Attribute::NoUndef);
+
+  if (const MDNode *Align = I.getMetadata(LLVMContext::MD_align)) {
+    ConstantInt *CI = mdconst::extract<ConstantInt>(Align->getOperand(0));
+    addAlignmentAttr(CI->getZExtValue());
+  }
+
+  if (const MDNode *Dereferenceable =
+          I.getMetadata(LLVMContext::MD_dereferenceable)) {
+    ConstantInt *CI =
+        mdconst::extract<ConstantInt>(Dereferenceable->getOperand(0));
+    addDereferenceableAttr(CI->getZExtValue());
+  }
+
+  if (const MDNode *DereferenceableOrNull =
+          I.getMetadata(LLVMContext::MD_dereferenceable_or_null)) {
+    ConstantInt *CI =
+        mdconst::extract<ConstantInt>(DereferenceableOrNull->getOperand(0));
+    addDereferenceableAttr(CI->getZExtValue());
+  }
+
+  if (const MDNode *Range = I.getMetadata(LLVMContext::MD_range))
+    addRangeAttr(getConstantRangeFromMetadata(*Range));
+
+  return *this;
+}
+
 AttrBuilder &AttrBuilder::merge(const AttrBuilder &B) {
   // TODO: Could make this O(n) as we're merging two sorted lists.
   for (const auto &I : B.attrs())

llvm/test/tools/llvm-reduce/reduce-operands-to-args-metadata-to-attributes.ll

@@ -0,0 +1,77 @@
+; Check that equivalent parameter attributes are introduced when
+; moving instructions with metadata to arguments.
+
+; RUN: llvm-reduce %s -o %t --abort-on-invalid-reduction --delta-passes=operands-to-args --test FileCheck --test-arg %s --test-arg --check-prefix=INTERESTING --test-arg --input-file
+; RUN: FileCheck --input-file %t --check-prefix=REDUCED %s
+
+; INTERESTING-LABEL: define ptr @use_nonnull(
+; REDUCED-LABEL: define ptr @use_nonnull(ptr nonnull %nonnull) {
+define ptr @use_nonnull() {
+  %nonnull = load ptr, ptr null, !nonnull !0
+  ret ptr %nonnull
+}
+
+; INTERESTING-LABEL: define void @use_noundef(
+; REDUCED-LABEL: define void @use_noundef(ptr noundef %noundef, <2 x ptr> noundef %noundef_vec) {
+define void @use_noundef() {
+  %noundef = load ptr, ptr null, !noundef !0
+  %noundef_vec = load <2 x ptr>, ptr null, !noundef !0
+  store ptr %noundef, ptr null
+  store <2 x ptr> %noundef_vec, ptr null
+  ret void
+}
+
+; INTERESTING-LABEL: define ptr @use_align(
+; REDUCED-LABEL: define ptr @use_align(ptr align 16 %align) {
+define ptr @use_align() {
+  %align = load ptr, ptr null, !align !1
+  ret ptr %align
+}
+
+; INTERESTING-LABEL: define ptr @use_dereferenceable(
+; REDUCED-LABEL: define ptr @use_dereferenceable(ptr dereferenceable(12345) %deref) {
+define ptr @use_dereferenceable() {
+  %deref = load ptr, ptr null, !dereferenceable !2
+  ret ptr %deref
+}
+
+; INTERESTING-LABEL: define ptr @use_dereferenceable_or_null(
+; REDUCED-LABEL: define ptr @use_dereferenceable_or_null(ptr dereferenceable(77777) %deref) {
+define ptr @use_dereferenceable_or_null() {
+  %deref = load ptr, ptr null, !dereferenceable_or_null !3
+  ret ptr %deref
+}
+
+; INTERESTING-LABEL: define void @use_range(
+; REDUCED-LABEL: define void @use_range(i32 range(i32 8, 25) %simple_range, i32 range(i32 8, 420) %disjoint_range, i32 range(i32 42, 0) %wrapping_range, <2 x i32> range(i32 8, 25) %vector_range) {
+define void @use_range() {
+  %simple_range = load i32, ptr null, !range !4
+  %disjoint_range = load i32, ptr null, !range !5
+  %wrapping_range = load i32, ptr null, !range !6
+  %vector_range = load <2 x i32>, ptr null, !range !4
+  store i32 %simple_range, ptr null
+  store i32 %disjoint_range, ptr null
+  store i32 %wrapping_range, ptr null
+  store <2 x i32> %vector_range, ptr null
+  ret void
+}
+
+; INTERESTING-LABEL: define void @use_noundef_range(
+; REDUCED-LABEL: define void @use_noundef_range(i32 noundef range(i32 8, 25) %load, <2 x i32> noundef range(i32 8, 25) %load_vec) {
+define void @use_noundef_range() {
+  %load = load i32, ptr null, !range !4, !noundef !0
+  %load_vec = load <2 x i32>, ptr null, !range !4, !noundef !0
+  store i32 %load, ptr null
+  store <2 x i32> %load_vec, ptr null
+  ret void
+}
+
+
+
+!0 = !{}
+!1 = !{i64 16}
+!2 = !{i64 12345}
+!3 = !{i64 77777}
+!4 = !{i32 8, i32 25}
+!5 = !{i32 8, i32 25, i32 69, i32 420}
+!6 = !{i32 42, i32 0}

llvm/tools/llvm-reduce/deltas/ReduceOperandsToArgs.cpp

@@ -159,6 +159,8 @@ static void substituteOperandWithArgument(Function *OldF,
     VMap[&OldArg] = &NewArg;          // Add mapping to VMap
   }
 
+  LLVMContext &Ctx = OldF->getContext();
+
   // Adjust the new parameters.
   ValueToValueMapTy OldValMap;
   for (auto Z : zip_first(UniqueValues, drop_begin(NewF->args(), ArgOffset))) {
@@ -175,9 +177,16 @@ static void substituteOperandWithArgument(Function *OldF,
 
   // Replace the actual operands.
   for (Use *Op : OpsToReplace) {
-    Value *NewArg = OldValMap.lookup(Op->get());
+    Argument *NewArg = cast<Argument>(OldValMap.lookup(Op->get()));
     auto *NewUser = cast<Instruction>(VMap.lookup(Op->getUser()));
 
+    // Try to preserve any information contained metadata annotations as the
+    // equivalent parameter attributes if possible.
+    if (auto *MDSrcInst = dyn_cast<Instruction>(Op)) {
+      AttrBuilder AB(Ctx);
+      NewArg->addAttrs(AB.addFromEquivalentMetadata(*MDSrcInst));
+    }
+
     if (PHINode *NewPhi = dyn_cast<PHINode>(NewUser)) {
       PHINode *OldPhi = cast<PHINode>(Op->getUser());
       BasicBlock *OldBB = OldPhi->getIncomingBlock(*Op);