From 90cb7089e364fdf09058bfb6a89a250fd7a871fb Mon Sep 17 00:00:00 2001
From: Chandler Carruth <chandlerc@gmail.com>
Date: Fri, 4 May 2012 11:20:27 +0000
Subject: Factor the computation of input and output sets into a public
 interface of the CodeExtractor utility. This allows speculatively computing
 input and output sets to measure the likely size impact of the code
 extraction.

These sets cannot be reused sadly -- we mutate the function prior to
forming the final sets used by the actual extraction.

The interface has been revamped slightly to make it easier to use
correctly by making the interface const and sinking the computation of
the number of exit blocks into the full extraction function and away
from the rest of this logic which just computed two output parameters.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156168 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Utils/CodeExtractor.cpp | 69 +++++++++++++++++-----------------
 1 file changed, 34 insertions(+), 35 deletions(-)

(limited to 'lib/Transforms/Utils/CodeExtractor.cpp')

diff --git a/lib/Transforms/Utils/CodeExtractor.cpp b/lib/Transforms/Utils/CodeExtractor.cpp
index 4d82857c1b..b23787dc49 100644
--- a/lib/Transforms/Utils/CodeExtractor.cpp
+++ b/lib/Transforms/Utils/CodeExtractor.cpp
@@ -109,7 +109,6 @@ CodeExtractor::CodeExtractor(DominatorTree &DT, Loop &L, bool AggregateArgs)
   : DT(&DT), AggregateArgs(AggregateArgs||AggregateArgsOpt),
     Blocks(buildExtractionBlockSet(L.getBlocks())), NumExitBlocks(~0U) {}
 
-
 /// definedInRegion - Return true if the specified value is defined in the
 /// extracted region.
 static bool definedInRegion(const SetVector<BasicBlock *> &Blocks, Value *V) {
@@ -130,6 +129,32 @@ static bool definedInCaller(const SetVector<BasicBlock *> &Blocks, Value *V) {
   return false;
 }
 
+void CodeExtractor::findInputsOutputs(ValueSet &Inputs,
+                                      ValueSet &Outputs) const {
+  for (SetVector<BasicBlock *>::const_iterator I = Blocks.begin(),
+                                               E = Blocks.end();
+       I != E; ++I) {
+    BasicBlock *BB = *I;
+
+    // If a used value is defined outside the region, it's an input.  If an
+    // instruction is used outside the region, it's an output.
+    for (BasicBlock::iterator II = BB->begin(), IE = BB->end();
+         II != IE; ++II) {
+      for (User::op_iterator OI = II->op_begin(), OE = II->op_end();
+           OI != OE; ++OI)
+        if (definedInCaller(Blocks, *OI))
+          Inputs.insert(*OI);
+
+      for (Value::use_iterator UI = II->use_begin(), UE = II->use_end();
+           UI != UE; ++UI)
+        if (!definedInRegion(Blocks, *UI)) {
+          Outputs.insert(II);
+          break;
+        }
+    }
+  }
+}
+
 /// severSplitPHINodes - If a PHI node has multiple inputs from outside of the
 /// region, we need to split the entry block of the region so that the PHI node
 /// is easier to deal with.
@@ -233,40 +258,6 @@ void CodeExtractor::splitReturnBlocks() {
     }
 }
 
-// findInputsOutputs - Find inputs to, outputs from the code region.
-//
-void CodeExtractor::findInputsOutputs(ValueSet &inputs, ValueSet &outputs) {
-  std::set<BasicBlock*> ExitBlocks;
-  for (SetVector<BasicBlock*>::const_iterator ci = Blocks.begin(),
-       ce = Blocks.end(); ci != ce; ++ci) {
-    BasicBlock *BB = *ci;
-
-    for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
-      // If a used value is defined outside the region, it's an input.  If an
-      // instruction is used outside the region, it's an output.
-      for (User::op_iterator O = I->op_begin(), E = I->op_end(); O != E; ++O)
-        if (definedInCaller(Blocks, *O))
-          inputs.insert(*O);
-
-      // Consider uses of this instruction (outputs).
-      for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
-           UI != E; ++UI)
-        if (!definedInRegion(Blocks, *UI)) {
-          outputs.insert(I);
-          break;
-        }
-    } // for: insts
-
-    // Keep track of the exit blocks from the region.
-    TerminatorInst *TI = BB->getTerminator();
-    for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
-      if (!Blocks.count(TI->getSuccessor(i)))
-        ExitBlocks.insert(TI->getSuccessor(i));
-  } // for: basic blocks
-
-  NumExitBlocks = ExitBlocks.size();
-}
-
 /// constructFunction - make a function based on inputs and outputs, as follows:
 /// f(in0, ..., inN, out0, ..., outN)
 ///
@@ -701,6 +692,14 @@ Function *CodeExtractor::extractCodeRegion() {
   // Find inputs to, outputs from the code region.
   findInputsOutputs(inputs, outputs);
 
+  SmallPtrSet<BasicBlock *, 1> ExitBlocks;
+  for (SetVector<BasicBlock *>::iterator I = Blocks.begin(), E = Blocks.end();
+       I != E; ++I)
+    for (succ_iterator SI = succ_begin(*I), SE = succ_end(*I); SI != SE; ++SI)
+      if (!Blocks.count(*SI))
+        ExitBlocks.insert(*SI);
+  NumExitBlocks = ExitBlocks.size();
+
   // Construct new function based on inputs/outputs & add allocas for all defs.
   Function *newFunction = constructFunction(inputs, outputs, header,
                                             newFuncRoot,
-- 
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