[llvm] r330136 - [Attributes] Fix a bug in AttributeList::get so it can handle a mix of FunctionIndex and ReturnIndex/arg indices at the same time

[Craig Topper via llvm-commits]

Author: ctopper
Date: Mon Apr 16 10:05:01 2018
New Revision: 330136

URL: http://llvm.org/viewvc/llvm-project?rev=330136&view=rev
Log:
[Attributes] Fix a bug in AttributeList::get so it can handle a mix of FunctionIndex and ReturnIndex/arg indices at the same time

The code uses the index of the last element in the sorted array to determine the maximum size needed for the vector. But if the last index is a FunctionIndex(~0), attrIdxToArrayIdx will return 0 and the vector will have size 1. If there are any indices before FunctionIndex, those values would return a value larger than 0 from attrIdxToArrayIdx. So in this case we need to look in front of the FunctionIndex to get the true size needed.

Differential Revision: https://reviews.llvm.org/D45632

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

Modified: llvm/trunk/lib/IR/Attributes.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/Attributes.cpp?rev=330136&r1=330135&r2=330136&view=diff
==============================================================================
--- llvm/trunk/lib/IR/Attributes.cpp (original)
+++ llvm/trunk/lib/IR/Attributes.cpp Mon Apr 16 10:05:01 2018
@@ -922,6 +922,10 @@ AttributeList::get(LLVMContext &C,
          "Pointless attribute!");
 
   unsigned MaxIndex = Attrs.back().first;
+  // If the MaxIndex is FunctionIndex and there are other indices in front
+  // of it, we need to use the largest of those to get the right size.
+  if (MaxIndex == FunctionIndex && Attrs.size() > 1)
+    MaxIndex = Attrs[Attrs.size() - 2].first;
 
   SmallVector<AttributeSet, 4> AttrVec(attrIdxToArrayIdx(MaxIndex) + 1);
   for (const auto Pair : Attrs)

Modified: llvm/trunk/unittests/IR/AttributesTest.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/IR/AttributesTest.cpp?rev=330136&r1=330135&r2=330136&view=diff
==============================================================================
--- llvm/trunk/unittests/IR/AttributesTest.cpp (original)
+++ llvm/trunk/unittests/IR/AttributesTest.cpp Mon Apr 16 10:05:01 2018
@@ -159,4 +159,12 @@ TEST(Attributes, EmptyGet) {
   EXPECT_TRUE(AL.isEmpty());
 }
 
+TEST(Attributes, OverflowGet) {
+  LLVMContext C;
+  std::pair<unsigned, Attribute> Attrs[] = { { AttributeList::ReturnIndex, Attribute::get(C, Attribute::SExt) },
+                                             { AttributeList::FunctionIndex, Attribute::get(C, Attribute::ReadOnly) } };
+  AttributeList AL = AttributeList::get(C, Attrs);
+  EXPECT_EQ(2U, AL.getNumAttrSets());
+}
+
 } // end anonymous namespace