From 3b1c95f8858b212252b66e2e0551a85b372b5b50 Mon Sep 17 00:00:00 2001
From: Devang Patel <dpatel@apple.com>
Date: Wed, 5 Mar 2008 21:50:24 +0000
Subject: Handle 'ret' with multiple values.

llvm-svn: 47965
---
 .../Transforms/Utils/UnifyFunctionExitNodes.cpp    | 34 +++++++++++++++-------
 1 file changed, 23 insertions(+), 11 deletions(-)

(limited to 'llvm/lib/Transforms')

diff --git a/llvm/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp b/llvm/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp
index 5d151ed70a0..7639d3f967f 100644
--- a/llvm/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp
+++ b/llvm/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp
@@ -20,6 +20,7 @@
 #include "llvm/Function.h"
 #include "llvm/Instructions.h"
 #include "llvm/Type.h"
+#include "llvm/ADT/SmallVector.h"
 using namespace llvm;
 
 char UnifyFunctionExitNodes::ID = 0;
@@ -50,11 +51,6 @@ bool UnifyFunctionExitNodes::runOnFunction(Function &F) {
   // Loop over all of the blocks in a function, tracking all of the blocks that
   // return.
   //
-
-  // PHINode can not handle aggregates returned by multiple value ret
-  // instructions. TODO: Handle each return value independently.
-  if (isa<StructType>(F.getReturnType()))
-    return false;
   std::vector<BasicBlock*> ReturningBlocks;
   std::vector<BasicBlock*> UnwindingBlocks;
   std::vector<BasicBlock*> UnreachableBlocks;
@@ -110,18 +106,30 @@ bool UnifyFunctionExitNodes::runOnFunction(Function &F) {
   }
 
   // Otherwise, we need to insert a new basic block into the function, add a PHI
-  // node (if the function returns a value), and convert all of the return
+  // nodes (if the function returns values), and convert all of the return
   // instructions into unconditional branches.
   //
   BasicBlock *NewRetBlock = new BasicBlock("UnifiedReturnBlock", &F);
 
-  PHINode *PN = 0;
-  if (F.getReturnType() != Type::VoidTy) {
+  SmallVector<Value *, 4> Phis;
+  unsigned NumRetVals = ReturningBlocks[0]->getTerminator()->getNumOperands();
+  if (NumRetVals == 0)
+    new ReturnInst(NULL, NewRetBlock);
+  else if (const StructType *STy = dyn_cast<StructType>(F.getReturnType())) {
+    for (unsigned i = 0; i < NumRetVals; ++i) {
+      PHINode *PN = new PHINode(STy->getElementType(i), "UnifiedRetVal");
+      NewRetBlock->getInstList().push_back(PN);
+      Phis.push_back(PN);
+    }
+    new ReturnInst(&Phis[0], NumRetVals);
+  }
+  else {
     // If the function doesn't return void... add a PHI node to the block...
-    PN = new PHINode(F.getReturnType(), "UnifiedRetVal");
+    PHINode *PN = new PHINode(F.getReturnType(), "UnifiedRetVal");
     NewRetBlock->getInstList().push_back(PN);
+    Phis.push_back(PN);
+    new ReturnInst(PN, NewRetBlock);
   }
-  new ReturnInst(PN, NewRetBlock);
 
   // Loop over all of the blocks, replacing the return instruction with an
   // unconditional branch.
@@ -132,7 +140,11 @@ bool UnifyFunctionExitNodes::runOnFunction(Function &F) {
 
     // Add an incoming element to the PHI node for every return instruction that
     // is merging into this new block...
-    if (PN) PN->addIncoming(BB->getTerminator()->getOperand(0), BB);
+    if (!Phis.empty()) {
+      for (unsigned i = 0; i < NumRetVals; ++i) 
+        cast<PHINode>(Phis[i])->addIncoming(BB->getTerminator()->getOperand(i), 
+                                            BB);
+    }
 
     BB->getInstList().pop_back();  // Remove the return insn
     new BranchInst(NewRetBlock, BB);
-- 
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