From f049c6712d77be98c9b448cf8b696b7bfffee85f Mon Sep 17 00:00:00 2001
From: Reid Spencer <rspencer@reidspencer.com>
Date: Mon, 29 Jan 2007 19:07:18 +0000
Subject: [PATCH] For PR1142: When an unresolved definition is found, check to
 see if it is only unresolved because the csretcc was upgraded to the sret
 param attribute. Such changes change the function type and lead to unresolved
 definitions. In such cases, just cast the function to the type expected by
 the CallInst. That is, cast to the version of the function that has the sret
 param attribute.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@33623 91177308-0d34-0410-b5e6-96231b3b80d8
---
 tools/llvm-upgrade/UpgradeParser.y | 43 +++++++++++++++++++++++++++---
 1 file changed, 39 insertions(+), 4 deletions(-)

diff --git a/tools/llvm-upgrade/UpgradeParser.y b/tools/llvm-upgrade/UpgradeParser.y
index 64a20d167cd..a5079d43e1e 100644
--- a/tools/llvm-upgrade/UpgradeParser.y
+++ b/tools/llvm-upgrade/UpgradeParser.y
@@ -505,6 +505,25 @@ static BasicBlock *getBBVal(const ValID &ID, bool isDefinition = false) {
 // and back patchs after we are done.
 //
 
+/// This function determines if two function types differ only in their use of
+/// the sret parameter attribute in the first argument. If they are identical 
+/// in all other respects, it returns true. Otherwise, it returns false.
+bool FuncTysDifferOnlyBySRet(const FunctionType *F1, 
+                                   const FunctionType *F2) {
+  if (F1->getReturnType() != F2->getReturnType() ||
+      F1->getNumParams() != F2->getNumParams() ||
+      F1->getParamAttrs(0) != F2->getParamAttrs(0))
+    return false;
+  unsigned SRetMask = ~unsigned(FunctionType::StructRetAttribute);
+  for (unsigned i = 0; i < F1->getNumParams(); ++i) {
+    if (F1->getParamType(i) != F2->getParamType(i) ||
+        unsigned(F1->getParamAttrs(i+1)) & SRetMask !=
+        unsigned(F2->getParamAttrs(i+1)) & SRetMask)
+      return false;
+  }
+  return true;
+}
+
 // ResolveDefinitions - If we could not resolve some defs at parsing
 // time (forward branches, phi functions for loops, etc...) resolve the
 // defs now...
@@ -537,10 +556,26 @@ ResolveDefinitions(std::map<const Type*,ValueList> &LateResolvers,
         InsertValue(V, *FutureLateResolvers);
       } else {
         if (DID.Type == ValID::NameVal) {
-          error("Reference to an invalid definition: '" +DID.getName()+
-                "' of type '" + V->getType()->getDescription() + "'",
-                PHI->second.second);
-          return;
+          // The upgrade of csretcc to sret param attribute may have caused a
+          // function to not be found because the param attribute changed the 
+          // type of the called function. Detect this situation and insert a 
+          // cast as necessary.
+          bool fixed = false;
+          if (const PointerType *PTy = dyn_cast<PointerType>(V->getType()))
+            if (const FunctionType *FTy =
+              dyn_cast<FunctionType>(PTy->getElementType()))
+              if (Function *OtherF =
+                CurModule.CurrentModule->getNamedFunction(DID.getName()))
+                if (FuncTysDifferOnlyBySRet(FTy,OtherF->getFunctionType())) {
+                  V->replaceAllUsesWith(ConstantExpr::getBitCast(OtherF, PTy));
+                  fixed = true;
+                }
+          if (!fixed) {
+            error("Reference to an invalid definition: '" +DID.getName()+
+                  "' of type '" + V->getType()->getDescription() + "'",
+                  PHI->second.second);
+            return;
+          }
         } else {
           error("Reference to an invalid definition: #" +
                 itostr(DID.Num) + " of type '" + 
-- 
2.34.1