From 257da0a7fc2df19444e57e7c84a278c6c1b9b551 Mon Sep 17 00:00:00 2001
From: Matthijs Kooijman <matthijs@stdin.nl>
Date: Thu, 5 Jun 2008 08:48:32 +0000
Subject: [PATCH] Let StructRetPromotion check if it's users are really calling
 it and not passing its pointer. Fixes test with added testcase.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51991 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/IPO/StructRetPromotion.cpp     |  4 ++++
 .../2008-06-04-function-pointer-passing.ll    | 24 +++++++++++++++++++
 2 files changed, 28 insertions(+)
 create mode 100644 test/Transforms/SRETPromotion/2008-06-04-function-pointer-passing.ll

diff --git a/lib/Transforms/IPO/StructRetPromotion.cpp b/lib/Transforms/IPO/StructRetPromotion.cpp
index 174a6fa7671..97a532b8b11 100644
--- a/lib/Transforms/IPO/StructRetPromotion.cpp
+++ b/lib/Transforms/IPO/StructRetPromotion.cpp
@@ -158,6 +158,10 @@ bool SRETPromotion::isSafeToUpdateAllCallers(Function *F) {
 
   for (Value::use_iterator FnUseI = F->use_begin(), FnUseE = F->use_end();
        FnUseI != FnUseE; ++FnUseI) {
+    // The function is passed in as an argument to (possibly) another function,
+    // we can't change it!
+    if (FnUseI.getOperandNo() != 0)
+      return false;
 
     CallSite CS = CallSite::get(*FnUseI);
     Instruction *Call = CS.getInstruction();
diff --git a/test/Transforms/SRETPromotion/2008-06-04-function-pointer-passing.ll b/test/Transforms/SRETPromotion/2008-06-04-function-pointer-passing.ll
new file mode 100644
index 00000000000..21701dd84be
--- /dev/null
+++ b/test/Transforms/SRETPromotion/2008-06-04-function-pointer-passing.ll
@@ -0,0 +1,24 @@
+; This test lures sretpromotion into promoting the sret argument of foo, even
+; when the function is used as an argument to bar. It used to not check for
+; this, assuming that all users of foo were direct calls, resulting in an
+; assertion failure later on.
+
+; We're mainly testing for opt not to crash, but we'll check to see if the sret
+; attribute is still there for good measure.
+; RUN: llvm-as < %s | opt -sretpromotion | llvm-dis | grep sret
+
+%struct.S = type <{ i32, i32 }>
+
+define i32 @main() {
+entry:
+	%tmp = alloca %struct.S		; <%struct.S*> [#uses=1]
+	call void @bar( %struct.S* sret  %tmp, void (%struct.S*, ...)* @foo )
+	ret i32 undef
+}
+
+declare void @bar(%struct.S* sret , void (%struct.S*, ...)*)
+
+define internal void @foo(%struct.S* sret  %agg.result, ...) {
+entry:
+	ret void
+}
-- 
2.34.1