Fix off-by-one bug in AttributeList::addAttributes index handling

getParamAlignment expects an argument number, not an AttributeList
index.

Johan Englan, who works on LDC, found this bug and told me about it off
list.

llvm-svn: 303458

2 files changed, 20 insertions, 1 deletions

diff --git a/llvm/lib/IR/Attributes.cpp b/llvm/lib/IR/Attributes.cpp
index ce60367a6c8..adb31d127a2 100644
--- a/llvm/lib/IR/Attributes.cpp
+++ b/llvm/lib/IR/Attributes.cpp
@@ -1058,7 +1058,7 @@ AttributeList AttributeList::addAttributes(LLVMContext &C, unsigned Index,
 #ifndef NDEBUG
   // FIXME it is not obvious how this should work for alignment. For now, say
   // we can't change a known alignment.
-  unsigned OldAlign = getParamAlignment(Index);
+  unsigned OldAlign = getAttributes(Index).getAlignment();
   unsigned NewAlign = B.getAlignment();
   assert((!OldAlign || !NewAlign || OldAlign == NewAlign) &&
          "Attempt to change alignment!");
diff --git a/llvm/unittests/IR/AttributesTest.cpp b/llvm/unittests/IR/AttributesTest.cpp
index 0df7a847f8a..7af4aebd540 100644
--- a/llvm/unittests/IR/AttributesTest.cpp
+++ b/llvm/unittests/IR/AttributesTest.cpp
@@ -63,4 +63,23 @@ TEST(Attributes, AddAttributes) {
   EXPECT_TRUE(AL.hasFnAttribute(Attribute::NoReturn));
 }
 
+TEST(Attributes, AddMatchingAlignAttr) {
+  LLVMContext C;
+  AttributeList AL;
+  AL = AL.addAttribute(C, AttributeList::FirstArgIndex,
+                       Attribute::getWithAlignment(C, 8));
+  AL = AL.addAttribute(C, AttributeList::FirstArgIndex + 1,
+                       Attribute::getWithAlignment(C, 32));
+  EXPECT_EQ(8U, AL.getParamAlignment(0));
+  EXPECT_EQ(32U, AL.getParamAlignment(1));
+
+  AttrBuilder B;
+  B.addAttribute(Attribute::NonNull);
+  B.addAlignmentAttr(8);
+  AL = AL.addAttributes(C, AttributeList::FirstArgIndex, B);
+  EXPECT_EQ(8U, AL.getParamAlignment(0));
+  EXPECT_EQ(32U, AL.getParamAlignment(1));
+  EXPECT_TRUE(AL.hasParamAttribute(0, Attribute::NonNull));
+}
+
 } // end anonymous namespace