From 22c96a966b111ed433ddab238e9f83109c0a824a Mon Sep 17 00:00:00 2001
From: Tim Northover <tnorthover@apple.com>
Date: Thu, 27 Jun 2019 11:44:45 +0000
Subject: [PATCH] IR: compare type attributes deeply when looking into
 functions.

FunctionComparator attempts to produce a stable comparison of two Function
instances by looking at all available properties. Since ByVal attributes now
contain a Type pointer, they are not trivially ordered and FunctionComparator
should use its own Type comparison logic to sort them.

llvm-svn: 364523
---
 .../Transforms/Utils/FunctionComparator.cpp   | 13 +++++++
 .../Transforms/MergeFunc/byval-attr-type.ll   | 37 +++++++++++++++++++
 2 files changed, 50 insertions(+)
 create mode 100644 llvm/test/Transforms/MergeFunc/byval-attr-type.ll

diff --git a/llvm/lib/Transforms/Utils/FunctionComparator.cpp b/llvm/lib/Transforms/Utils/FunctionComparator.cpp
index 5c400cec5734..a9b28754c8e9 100644
--- a/llvm/lib/Transforms/Utils/FunctionComparator.cpp
+++ b/llvm/lib/Transforms/Utils/FunctionComparator.cpp
@@ -113,6 +113,19 @@ int FunctionComparator::cmpAttrs(const AttributeList L,
     for (; LI != LE && RI != RE; ++LI, ++RI) {
       Attribute LA = *LI;
       Attribute RA = *RI;
+      if (LA.isTypeAttribute() && RA.isTypeAttribute()) {
+        if (LA.getKindAsEnum() != RA.getKindAsEnum())
+          return cmpNumbers(LA.getKindAsEnum(), RA.getKindAsEnum());
+
+        Type *TyL = LA.getValueAsType();
+        Type *TyR = RA.getValueAsType();
+        if (TyL && TyR)
+          return cmpTypes(TyL, TyR);
+
+        // 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 (LA < RA)
         return -1;
       if (RA < LA)
diff --git a/llvm/test/Transforms/MergeFunc/byval-attr-type.ll b/llvm/test/Transforms/MergeFunc/byval-attr-type.ll
new file mode 100644
index 000000000000..b6592136147a
--- /dev/null
+++ b/llvm/test/Transforms/MergeFunc/byval-attr-type.ll
@@ -0,0 +1,37 @@
+; RUN: opt -S -mergefunc %s | FileCheck %s
+
+@i = global i32 0
+@f = global float 0.0
+
+define internal void @foo() {
+; CHECK: define internal void @foo()
+  call void @callee_i32(i32* byval(i32) @i)
+  ret void
+}
+
+define internal void @bar() {
+; CHECK: define internal void @bar()
+  call void @callee_float(float* byval(float) @f)
+  ret void
+}
+
+define internal void @baz() {
+; CHECK-NOT: define{{.*}}@bar
+  call void @callee_float(float* byval(float) @f)
+  ret void
+}
+
+define void @user() {
+; CHECK-LABEL: define void @user
+; CHECK: call void @foo()
+; CHECK: call void @bar()
+; CHECK: call void @bar()
+
+  call void @foo()
+  call void @bar()
+  call void @baz()
+  ret void
+}
+
+declare void @callee_i32(i32* byval(i32))
+declare void @callee_float(float* byval(float))