From ae2612e12e4d8e20d55529e13eacbfac416fe186 Mon Sep 17 00:00:00 2001
From: Peter Collingbourne <peter@pcc.me.uk>
Date: Thu, 9 Feb 2017 23:46:26 +0000
Subject: [PATCH] WholeProgramDevirt: Check that VCP candidate functions are
 defined before evaluating them.

This was crashing before.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294666 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/IPO/WholeProgramDevirt.cpp     | 10 +++---
 .../Transforms/WholeProgramDevirt/vcp-decl.ll | 32 +++++++++++++++++++
 2 files changed, 37 insertions(+), 5 deletions(-)
 create mode 100644 test/Transforms/WholeProgramDevirt/vcp-decl.ll

diff --git a/lib/Transforms/IPO/WholeProgramDevirt.cpp b/lib/Transforms/IPO/WholeProgramDevirt.cpp
index 844cc0f70ee..66c4f6eb86d 100644
--- a/lib/Transforms/IPO/WholeProgramDevirt.cpp
+++ b/lib/Transforms/IPO/WholeProgramDevirt.cpp
@@ -571,12 +571,12 @@ bool DevirtModule::tryVirtualConstProp(
   if (BitWidth > 64)
     return false;
 
-  // Make sure that each function does not access memory, takes at least one
-  // argument, does not use its first argument (which we assume is 'this'),
-  // and has the same return type.
+  // Make sure that each function is defined, does not access memory, takes at
+  // least one argument, does not use its first argument (which we assume is
+  // 'this'), and has the same return type.
   for (VirtualCallTarget &Target : TargetsForSlot) {
-    if (!Target.Fn->doesNotAccessMemory() || Target.Fn->arg_empty() ||
-        !Target.Fn->arg_begin()->use_empty() ||
+    if (Target.Fn->isDeclaration() || !Target.Fn->doesNotAccessMemory() ||
+        Target.Fn->arg_empty() || !Target.Fn->arg_begin()->use_empty() ||
         Target.Fn->getReturnType() != RetType)
       return false;
   }
diff --git a/test/Transforms/WholeProgramDevirt/vcp-decl.ll b/test/Transforms/WholeProgramDevirt/vcp-decl.ll
new file mode 100644
index 00000000000..1c4e2fbe97a
--- /dev/null
+++ b/test/Transforms/WholeProgramDevirt/vcp-decl.ll
@@ -0,0 +1,32 @@
+; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
+
+target datalayout = "e-p:64:64"
+target triple = "x86_64-unknown-linux-gnu"
+
+@vt1 = constant [1 x i8*] [i8* bitcast (i32 (i8*, i32)* @vf1 to i8*)], !type !0
+@vt2 = constant [1 x i8*] [i8* bitcast (i32 (i8*, i32)* @vf2 to i8*)], !type !0
+
+declare i32 @vf1(i8* %this, i32 %arg) readnone
+
+define i32 @vf2(i8* %this, i32 %arg) readnone {
+  ret i32 %arg
+}
+
+; CHECK: define i32 @fn
+define i32 @fn(i8* %obj) {
+  %vtableptr = bitcast i8* %obj to [1 x i8*]**
+  %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
+  %vtablei8 = bitcast [1 x i8*]* %vtable to i8*
+  %p = call i1 @llvm.type.test(i8* %vtablei8, metadata !"typeid")
+  call void @llvm.assume(i1 %p)
+  %fptrptr = getelementptr [1 x i8*], [1 x i8*]* %vtable, i32 0, i32 0
+  %fptr = load i8*, i8** %fptrptr
+  %fptr_casted = bitcast i8* %fptr to i32 (i8*, i32)*
+  ; CHECK: call i32 %
+  %result = call i32 %fptr_casted(i8* %obj, i32 1)
+  ret i32 %result
+}
+declare i1 @llvm.type.test(i8*, metadata)
+declare void @llvm.assume(i1)
+
+!0 = !{i32 0, !"typeid"}
-- 
2.40.0