From 30a94e3b4203cee64db0edd997780bbe4ad0acdc Mon Sep 17 00:00:00 2001
From: Torok Edwin <edwintorok@gmail.com>
Date: Thu, 24 Sep 2009 09:47:18 +0000
Subject: [PATCH] Don't constant propagate byval pointers, since they are not
 really pointers, but rather structs passed by value. This fixes PR5038.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82689 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/IPO/IPConstantPropagation.cpp  |  3 ++-
 lib/Transforms/Scalar/SCCP.cpp                |  4 ++++
 .../IPConstantProp/2009-09-24-byval-ptr.ll    | 24 +++++++++++++++++++
 3 files changed, 30 insertions(+), 1 deletion(-)
 create mode 100644 test/Transforms/IPConstantProp/2009-09-24-byval-ptr.ll

diff --git a/lib/Transforms/IPO/IPConstantPropagation.cpp b/lib/Transforms/IPO/IPConstantPropagation.cpp
index bb2448610f2..95c3f4e3548 100644
--- a/lib/Transforms/IPO/IPConstantPropagation.cpp
+++ b/lib/Transforms/IPO/IPConstantPropagation.cpp
@@ -130,7 +130,8 @@ bool IPCP::PropagateConstantsIntoArguments(Function &F) {
   Function::arg_iterator AI = F.arg_begin();
   for (unsigned i = 0, e = ArgumentConstants.size(); i != e; ++i, ++AI) {
     // Do we have a constant argument?
-    if (ArgumentConstants[i].second || AI->use_empty())
+    if (ArgumentConstants[i].second || AI->use_empty() || 
+        (AI->hasByValAttr() && isa<PointerType>(AI->getType())))
       continue;
   
     Value *V = ArgumentConstants[i].first;
diff --git a/lib/Transforms/Scalar/SCCP.cpp b/lib/Transforms/Scalar/SCCP.cpp
index f0b5d7702e3..bf9ec0e4adf 100644
--- a/lib/Transforms/Scalar/SCCP.cpp
+++ b/lib/Transforms/Scalar/SCCP.cpp
@@ -1267,6 +1267,10 @@ CallOverdefined:
   for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
        AI != E; ++AI, ++CAI) {
     LatticeVal &IV = ValueState[AI];
+    if (AI->hasByValAttr() && isa<PointerType>(AI->getType())) {
+      IV.markOverdefined();
+      continue;
+    }
     if (!IV.isOverdefined())
       mergeInValue(IV, AI, getValueState(*CAI));
   }
diff --git a/test/Transforms/IPConstantProp/2009-09-24-byval-ptr.ll b/test/Transforms/IPConstantProp/2009-09-24-byval-ptr.ll
new file mode 100644
index 00000000000..75055d41a64
--- /dev/null
+++ b/test/Transforms/IPConstantProp/2009-09-24-byval-ptr.ll
@@ -0,0 +1,24 @@
+; RUN: llvm-as <%s | opt -ipsccp | llvm-dis | FileCheck %s
+; Don't constant-propagate byval pointers, since they are not pointers!
+; PR5038
+%struct.MYstr = type { i8, i32 }
+@mystr = internal global %struct.MYstr zeroinitializer ; <%struct.MYstr*> [#uses=3]
+define internal void @vfu1(%struct.MYstr* byval align 4 %u) nounwind {
+entry:
+  %0 = getelementptr %struct.MYstr* %u, i32 0, i32 1 ; <i32*> [#uses=1]
+  store i32 99, i32* %0, align 4
+; CHECK: %struct.MYstr* %u
+  %1 = getelementptr %struct.MYstr* %u, i32 0, i32 0 ; <i8*> [#uses=1]
+  store i8 97, i8* %1, align 4
+; CHECK: %struct.MYstr* %u
+  br label %return
+
+return:                                           ; preds = %entry
+  ret void
+}
+define void @unions() nounwind {
+entry:
+  call void @vfu1(%struct.MYstr* byval align 4 @mystr) nounwind
+  ret void
+}
+