From f7fe7ea24d368f45deee1aed5e4c582ac69edd0b Mon Sep 17 00:00:00 2001
From: Tim Northover <t.p.northover@gmail.com>
Date: Mon, 9 Nov 2020 09:19:11 +0000
Subject: [PATCH] [MergeFunctions] fix function attribute comparison in
 FunctionComparator

The comparison of AttributeSets stopped after seeing a matching type attribute.
Subsequent mismatching attributes were not detected causing a crash.
---
 llvm/lib/Transforms/Utils/FunctionComparator.cpp    | 11 ++++++++---
 .../Transforms/MergeFunc/mismatching-attr-crash.ll  | 21 +++++++++++++++++++++
 2 files changed, 29 insertions(+), 3 deletions(-)
 create mode 100644 llvm/test/Transforms/MergeFunc/mismatching-attr-crash.ll

diff --git a/llvm/lib/Transforms/Utils/FunctionComparator.cpp b/llvm/lib/Transforms/Utils/FunctionComparator.cpp
index dfab936..f25c4e5 100644
--- a/llvm/lib/Transforms/Utils/FunctionComparator.cpp
+++ b/llvm/lib/Transforms/Utils/FunctionComparator.cpp
@@ -124,12 +124,17 @@ int FunctionComparator::cmpAttrs(const AttributeList L,
 
         Type *TyL = LA.getValueAsType();
         Type *TyR = RA.getValueAsType();
-        if (TyL && TyR)
-          return cmpTypes(TyL, TyR);
+        if (TyL && TyR) {
+          if (int Res = cmpTypes(TyL, TyR))
+            return Res;
+          continue;
+        }
 
         // Two pointers, at least one null, so the comparison result is
         // independent of the value of a real pointer.
-        return cmpNumbers((uint64_t)TyL, (uint64_t)TyR);
+        if (int Res = cmpNumbers((uint64_t)TyL, (uint64_t)TyR))
+          return Res;
+        continue;
       }
       if (LA < RA)
         return -1;
diff --git a/llvm/test/Transforms/MergeFunc/mismatching-attr-crash.ll b/llvm/test/Transforms/MergeFunc/mismatching-attr-crash.ll
new file mode 100644
index 0000000..e3f81c5
--- /dev/null
+++ b/llvm/test/Transforms/MergeFunc/mismatching-attr-crash.ll
@@ -0,0 +1,21 @@
+; RUN: opt -S -mergefunc %s | FileCheck %s
+
+; CHECK-LABEL: define void @foo
+; CHECK: call void %bc
+define void @foo(i8* byval %a0, i8* swiftself %a4) {
+entry:
+  %bc = bitcast i8* %a0 to void (i8*, i8*)*
+  call void %bc(i8* byval %a0, i8* swiftself %a4)
+  ret void
+}
+
+; CHECK-LABEL: define void @bar
+; CHECK: call void %bc
+define void @bar(i8* byval(i8) %a0, i8** swifterror %a4) {
+entry:
+  %bc = bitcast i8* %a0 to void (i8*, i8**)*
+  call void %bc(i8* byval(i8) %a0, i8** swifterror %a4)
+  ret void
+}
+
+
-- 
2.7.4