From: Chris Lattner Date: Wed, 21 Oct 2009 23:41:58 +0000 (+0000) Subject: revert r84754, it isn't the right approach. Edwin, please propose X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=857eb5793e5d7fc239f75be3a39d9569914aebf0;p=oota-llvm.git revert r84754, it isn't the right approach. Edwin, please propose patches for fixes like this instead of committing them directly. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84799 91177308-0d34-0410-b5e6-96231b3b80d8 --- diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index 1088684b0a6..9147a9954aa 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -1985,42 +1985,6 @@ static Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI, return 0; } -// Check whether all the operands of the PHI dominate the PHI node, -// knowing that the PHI's operands either dominate BB, or are defined in the BB. -static bool checkPHI(PHINode *PN, BasicBlock *BB) -{ - BasicBlock *phiBB = PN->getParent(); - for (unsigned i=0;igetNumIncomingValues();i++) { - Instruction *I = dyn_cast(PN->getIncomingValue(i)); - if (!I) - continue; - BasicBlock *pBB = I->getParent(); - if (pBB == BB) { - // another PHI in same BB is always before PN (PN is last phi). - if (isa(I)) - continue; - // An instruction in the same BB, and not a phi, this is after PN. - return false; - } - if (phiBB == BB) - continue; - // We don't have dominator info, so just check that the instruction - // is not defined in on of the BB on the unique path between BB and phiBB. - // If there is no such unique path, or pBB equals to one of the BBs on that - // path we know that this operand doesn't dominate the PHI node. - BasicBlock *B = PN->getIncomingBlock(i); - while ((B = B->getUniquePredecessor())) { - if (pBB == B) - return false; - if (B == phiBB) - break; - } - // No unique path -> doesn't dominate - if (!B) - return false; - } - return true; -} /// FoldOpIntoPhi - Given a binary operator, cast instruction, or select which /// has a PHI node as operand #0, see if we can fold the instruction into the @@ -2072,13 +2036,9 @@ Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I, // Okay, we can do the transformation: create the new PHI node. PHINode *NewPN = PHINode::Create(I.getType(), ""); NewPN->reserveOperandSpace(PN->getNumOperands()/2); - // We must the PHI node as the last PHI, because it may use one of the other - // PHIs. - BasicBlock::iterator BBIt = PN; - while (isa(BBIt)) ++BBIt; - InsertNewInstBefore(NewPN, *BBIt); + InsertNewInstBefore(NewPN, *PN); + NewPN->takeName(PN); - SmallVector tmpWorklist; // Next, add all of the operands to the PHI. if (SelectInst *SI = dyn_cast(&I)) { // We only currently try to fold the condition of a select when it is a phi, @@ -2098,7 +2058,7 @@ Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I, InV = SelectInst::Create(PN->getIncomingValue(i), TrueVInPred, FalseVInPred, "phitmp", NonConstBB->getTerminator()); - tmpWorklist.push_back(cast(InV)); + Worklist.Add(cast(InV)); } NewPN->addIncoming(InV, ThisBB); } @@ -2124,7 +2084,8 @@ Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I, NonConstBB->getTerminator()); else llvm_unreachable("Unknown binop!"); - tmpWorklist.push_back(cast(InV)); + + Worklist.Add(cast(InV)); } NewPN->addIncoming(InV, PN->getIncomingBlock(i)); } @@ -2140,26 +2101,11 @@ Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I, InV = CastInst::Create(CI->getOpcode(), PN->getIncomingValue(i), I.getType(), "phitmp", NonConstBB->getTerminator()); - tmpWorklist.push_back(cast(InV)); + Worklist.Add(cast(InV)); } NewPN->addIncoming(InV, PN->getIncomingBlock(i)); } } - // The PHI's operands must dominate the PHI, if we can't prove that - // undo this transformation. - if (!checkPHI(NewPN, I.getParent())) { - Worklist.Remove(NewPN); - NewPN->eraseFromParent(); - while (!tmpWorklist.empty()) { - tmpWorklist.pop_back_val()->eraseFromParent(); - } - return 0; - } - while (!tmpWorklist.empty()) { - Worklist.Add(tmpWorklist.pop_back_val()); - } - NewPN->takeName(PN); - Worklist.Add(PN); return ReplaceInstUsesWith(I, NewPN); } diff --git a/test/Transforms/InstCombine/fold-intophi.ll b/test/Transforms/InstCombine/fold-intophi.ll deleted file mode 100644 index 23b482db19e..00000000000 --- a/test/Transforms/InstCombine/fold-intophi.ll +++ /dev/null @@ -1,54 +0,0 @@ -; RUN: opt -instcombine -S <%s | FileCheck %s -; PR5262 -; Make sure the PHI node gets put in a place where all of its operands dominate it -target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128" -target triple = "x86_64-unknown-linux-gnu" - -@tmp2 = global i64 0 ; [#uses=1] - -declare void @use(i64) nounwind - -define void @foo(i1) nounwind align 2 { -;