[llvm] 66dcb86 - [Attributes] Remove trailing empty attribute sets (PR59746)

[Nikita Popov via llvm-commits]

Author: Nikita Popov
Date: 2023-01-05T17:14:37+01:00
New Revision: 66dcb86b8bd9bdd1510c8eb797b4845cac0d3263

URL: https://github.com/llvm/llvm-project/commit/66dcb86b8bd9bdd1510c8eb797b4845cac0d3263
DIFF: https://github.com/llvm/llvm-project/commit/66dcb86b8bd9bdd1510c8eb797b4845cac0d3263.diff

LOG: [Attributes] Remove trailing empty attribute sets (PR59746)

In setAttributesAtIndex(), remove any trailing empty attribute sets.
Also make sure that all the different attribute removal APIs go
through that method.

Fixes https://github.com/llvm/llvm-project/issues/59746.

Added: 
    

Modified: 
    llvm/lib/IR/Attributes.cpp
    llvm/unittests/IR/AttributesTest.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/IR/Attributes.cpp b/llvm/lib/IR/Attributes.cpp
index 8b45d5eba833f..2c27c1aba5482 100644
--- a/llvm/lib/IR/Attributes.cpp
+++ b/llvm/lib/IR/Attributes.cpp
@@ -1333,6 +1333,12 @@ AttributeList AttributeList::setAttributesAtIndex(LLVMContext &C,
   if (Index >= AttrSets.size())
     AttrSets.resize(Index + 1);
   AttrSets[Index] = Attrs;
+
+  // Remove trailing empty attribute sets.
+  while (!AttrSets.empty() && !AttrSets.back().hasAttributes())
+    AttrSets.pop_back();
+  if (AttrSets.empty())
+    return {};
   return AttributeList::getImpl(C, AttrSets);
 }
 
@@ -1375,14 +1381,8 @@ AttributeList::removeAttributeAtIndex(LLVMContext &C, unsigned Index,
                                       Attribute::AttrKind Kind) const {
   if (!hasAttributeAtIndex(Index, Kind))
     return *this;
-
-  Index = attrIdxToArrayIdx(Index);
-  SmallVector<AttributeSet, 4> AttrSets(this->begin(), this->end());
-  assert(Index < AttrSets.size());
-
-  AttrSets[Index] = AttrSets[Index].removeAttribute(C, Kind);
-
-  return getImpl(C, AttrSets);
+  return setAttributesAtIndex(C, Index,
+                              getAttributes(Index).removeAttribute(C, Kind));
 }
 
 AttributeList AttributeList::removeAttributeAtIndex(LLVMContext &C,
@@ -1390,14 +1390,8 @@ AttributeList AttributeList::removeAttributeAtIndex(LLVMContext &C,
                                                     StringRef Kind) const {
   if (!hasAttributeAtIndex(Index, Kind))
     return *this;
-
-  Index = attrIdxToArrayIdx(Index);
-  SmallVector<AttributeSet, 4> AttrSets(this->begin(), this->end());
-  assert(Index < AttrSets.size());
-
-  AttrSets[Index] = AttrSets[Index].removeAttribute(C, Kind);
-
-  return getImpl(C, AttrSets);
+  return setAttributesAtIndex(C, Index,
+                              getAttributes(Index).removeAttribute(C, Kind));
 }
 
 AttributeList AttributeList::removeAttributesAtIndex(
@@ -1415,12 +1409,9 @@ AttributeList::removeAttributesAtIndex(LLVMContext &C,
                                        unsigned WithoutIndex) const {
   if (!pImpl)
     return {};
-  WithoutIndex = attrIdxToArrayIdx(WithoutIndex);
-  if (WithoutIndex >= getNumAttrSets())
+  if (attrIdxToArrayIdx(WithoutIndex) >= getNumAttrSets())
     return *this;
-  SmallVector<AttributeSet, 4> AttrSets(this->begin(), this->end());
-  AttrSets[WithoutIndex] = AttributeSet();
-  return getImpl(C, AttrSets);
+  return setAttributesAtIndex(C, WithoutIndex, AttributeSet());
 }
 
 AttributeList AttributeList::addDereferenceableRetAttr(LLVMContext &C,

diff  --git a/llvm/unittests/IR/AttributesTest.cpp b/llvm/unittests/IR/AttributesTest.cpp
index fcd7a22d2050f..5883ad71f9f6f 100644
--- a/llvm/unittests/IR/AttributesTest.cpp
+++ b/llvm/unittests/IR/AttributesTest.cpp
@@ -294,4 +294,17 @@ TEST(Attributes, MismatchedABIAttrs) {
   }
 }
 
+TEST(Attributes, RemoveParamAttributes) {
+  LLVMContext C;
+  AttributeList AL;
+  AL = AL.addParamAttribute(C, 1, Attribute::NoUndef);
+  EXPECT_EQ(AL.getNumAttrSets(), 4);
+  AL = AL.addParamAttribute(C, 3, Attribute::NonNull);
+  EXPECT_EQ(AL.getNumAttrSets(), 6);
+  AL = AL.removeParamAttributes(C, 3);
+  EXPECT_EQ(AL.getNumAttrSets(), 4);
+  AL = AL.removeParamAttribute(C, 1, Attribute::NoUndef);
+  EXPECT_EQ(AL.getNumAttrSets(), 0);
+}
+
 } // end anonymous namespace