From: Torok Edwin <edwintorok@gmail.com>
Date: Thu, 24 Sep 2009 18:33:42 +0000 (+0000)
Subject: Constant propagating byval pointer is safe if function is readonly.
X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=commitdiff_plain;h=c3384995258efcec26acf3a88715dc99cd871c3e

Constant propagating byval pointer is safe if function is readonly.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82700 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/IPO/IPConstantPropagation.cpp b/lib/Transforms/IPO/IPConstantPropagation.cpp
index 95c3f4e3548..7b0e9c727cd 100644
--- a/lib/Transforms/IPO/IPConstantPropagation.cpp
+++ b/lib/Transforms/IPO/IPConstantPropagation.cpp
@@ -130,8 +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() || 
-        (AI->hasByValAttr() && isa<PointerType>(AI->getType())))
+    if (ArgumentConstants[i].second || AI->use_empty() ||
+        (AI->hasByValAttr() && !F.onlyReadsMemory()))
       continue;
   
     Value *V = ArgumentConstants[i].first;
diff --git a/lib/Transforms/Scalar/SCCP.cpp b/lib/Transforms/Scalar/SCCP.cpp
index bf9ec0e4adf..ad4bcc942d0 100644
--- a/lib/Transforms/Scalar/SCCP.cpp
+++ b/lib/Transforms/Scalar/SCCP.cpp
@@ -1267,7 +1267,7 @@ 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())) {
+    if (AI->hasByValAttr() && !F->onlyReadsMemory()) {
       IV.markOverdefined();
       continue;
     }
diff --git a/test/Transforms/IPConstantProp/2009-09-24-byval-ptr.ll b/test/Transforms/IPConstantProp/2009-09-24-byval-ptr.ll
index 75055d41a64..f4bab353cd0 100644
--- a/test/Transforms/IPConstantProp/2009-09-24-byval-ptr.ll
+++ b/test/Transforms/IPConstantProp/2009-09-24-byval-ptr.ll
@@ -16,9 +16,25 @@ entry:
 return:                                           ; preds = %entry
   ret void
 }
-define void @unions() nounwind {
+
+define internal i32 @vfu2(%struct.MYstr* byval align 4 %u) nounwind readonly {
+entry:
+  %0 = getelementptr %struct.MYstr* %u, i32 0, i32 1 ; <i32*> [#uses=1]
+  %1 = load i32* %0
+; CHECK: load i32* getelementptr inbounds (%struct.MYstr* @mystr, i32 0, i32 1) ; <i32> [#uses=1]
+  %2 = getelementptr %struct.MYstr* %u, i32 0, i32 0 ; <i8*> [#uses=1]
+  %3 = load i8* %2
+; CHECK: load i8* getelementptr inbounds (%struct.MYstr* @mystr, i32 0, i32 0) ; <i8> [#uses=1]
+  %4 = zext i8 %3 to i32
+  %5 = add i32 %4, %1
+  ret i32 %5
+}
+
+define i32 @unions() nounwind {
 entry:
   call void @vfu1(%struct.MYstr* byval align 4 @mystr) nounwind
-  ret void
+  %result = call i32 @vfu2(%struct.MYstr* byval align 4 @mystr) nounwind
+
+  ret i32 %result
 }