It's not necessary to do rounding for alloca operations when the requested
alignment is equal to the stack alignment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40004 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/LowerSelect.cpp b/lib/Transforms/Utils/LowerSelect.cpp
new file mode 100644
index 0000000..1882695
--- /dev/null
+++ b/lib/Transforms/Utils/LowerSelect.cpp
@@ -0,0 +1,105 @@
+//===- LowerSelect.cpp - Transform select insts to branches ---------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass lowers select instructions into conditional branches for targets
+// that do not have conditional moves or that have not implemented the select
+// instruction yet.
+//
+// Note that this pass could be improved. In particular it turns every select
+// instruction into a new conditional branch, even though some common cases have
+// select instructions on the same predicate next to each other. It would be
+// better to use the same branch for the whole group of selects.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h"
+#include "llvm/Function.h"
+#include "llvm/Instructions.h"
+#include "llvm/Pass.h"
+#include "llvm/Type.h"
+#include "llvm/Support/Compiler.h"
+using namespace llvm;
+
+namespace {
+ /// LowerSelect - Turn select instructions into conditional branches.
+ ///
+ class VISIBILITY_HIDDEN LowerSelect : public FunctionPass {
+ bool OnlyFP; // Only lower FP select instructions?
+ public:
+ static char ID; // Pass identification, replacement for typeid
+ LowerSelect(bool onlyfp = false) : FunctionPass((intptr_t)&ID),
+ OnlyFP(onlyfp) {}
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ // This certainly destroys the CFG.
+ // This is a cluster of orthogonal Transforms:
+ AU.addPreserved<UnifyFunctionExitNodes>();
+ AU.addPreservedID(PromoteMemoryToRegisterID);
+ AU.addPreservedID(LowerSwitchID);
+ AU.addPreservedID(LowerInvokePassID);
+ AU.addPreservedID(LowerAllocationsID);
+ }
+
+ bool runOnFunction(Function &F);
+ };
+
+ char LowerSelect::ID = 0;
+ RegisterPass<LowerSelect>
+ X("lowerselect", "Lower select instructions to branches");
+}
+
+// Publically exposed interface to pass...
+const PassInfo *llvm::LowerSelectID = X.getPassInfo();
+//===----------------------------------------------------------------------===//
+// This pass converts SelectInst instructions into conditional branch and PHI
+// instructions. If the OnlyFP flag is set to true, then only floating point
+// select instructions are lowered.
+//
+FunctionPass *llvm::createLowerSelectPass(bool OnlyFP) {
+ return new LowerSelect(OnlyFP);
+}
+
+
+bool LowerSelect::runOnFunction(Function &F) {
+ bool Changed = false;
+ for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
+ for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
+ if (SelectInst *SI = dyn_cast<SelectInst>(I))
+ if (!OnlyFP || SI->getType()->isFloatingPoint()) {
+ // Split this basic block in half right before the select instruction.
+ BasicBlock *NewCont =
+ BB->splitBasicBlock(I, BB->getName()+".selectcont");
+
+ // Make the true block, and make it branch to the continue block.
+ BasicBlock *NewTrue = new BasicBlock(BB->getName()+".selecttrue",
+ BB->getParent(), NewCont);
+ new BranchInst(NewCont, NewTrue);
+
+ // Make the unconditional branch in the incoming block be a
+ // conditional branch on the select predicate.
+ BB->getInstList().erase(BB->getTerminator());
+ new BranchInst(NewTrue, NewCont, SI->getCondition(), BB);
+
+ // Create a new PHI node in the cont block with the entries we need.
+ PHINode *PN = new PHINode(SI->getType(), "", NewCont->begin());
+ PN->takeName(SI);
+ PN->addIncoming(SI->getTrueValue(), NewTrue);
+ PN->addIncoming(SI->getFalseValue(), BB);
+
+ // Use the PHI instead of the select.
+ SI->replaceAllUsesWith(PN);
+ NewCont->getInstList().erase(SI);
+
+ Changed = true;
+ break; // This block is done with.
+ }
+ }
+ return Changed;
+}