[llvm-commits] [llvm] r126825 - in /llvm/trunk: lib/Transforms/Scalar/CodeGenPrepare.cpp test/CodeGen/ARM/code-placement.ll test/CodeGen/X86/2010-09-30-CMOV-JumpTable-PHI.ll
Cameron Zwarich
zwarich at apple.com
Tue Mar 1 19:31:46 PST 2011
Author: zwarich
Date: Tue Mar 1 21:31:46 2011
New Revision: 126825
URL: http://llvm.org/viewvc/llvm-project?rev=126825&view=rev
Log:
Eliminate the unused CodeGenPrepare option to split critical edges.
Modified:
llvm/trunk/lib/Transforms/Scalar/CodeGenPrepare.cpp
llvm/trunk/test/CodeGen/ARM/code-placement.ll
llvm/trunk/test/CodeGen/X86/2010-09-30-CMOV-JumpTable-PHI.ll
Modified: llvm/trunk/lib/Transforms/Scalar/CodeGenPrepare.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/CodeGenPrepare.cpp?rev=126825&r1=126824&r2=126825&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/CodeGenPrepare.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/CodeGenPrepare.cpp Tue Mar 1 21:31:46 2011
@@ -58,11 +58,6 @@
STATISTIC(NumExtsMoved, "Number of [s|z]ext instructions combined with loads");
STATISTIC(NumExtUses, "Number of uses of [s|z]ext instructions optimized");
-static cl::opt<bool>
-CriticalEdgeSplit("cgp-critical-edge-splitting",
- cl::desc("Split critical edges during codegen prepare"),
- cl::init(false), cl::Hidden);
-
namespace {
class CodeGenPrepare : public FunctionPass {
/// TLI - Keep a pointer of a TargetLowering to consult for determining
@@ -144,11 +139,6 @@
// unconditional branch.
EverMadeChange |= EliminateMostlyEmptyBlocks(F);
- // Now find loop back edges, but only if they are being used to decide which
- // critical edges to split.
- if (CriticalEdgeSplit)
- findLoopBackEdges(F);
-
bool MadeChange = true;
while (MadeChange) {
MadeChange = false;
@@ -350,110 +340,6 @@
DEBUG(dbgs() << "AFTER:\n" << *DestBB << "\n\n\n");
}
-/// FindReusablePredBB - Check all of the predecessors of the block DestPHI
-/// lives in to see if there is a block that we can reuse as a critical edge
-/// from TIBB.
-static BasicBlock *FindReusablePredBB(PHINode *DestPHI, BasicBlock *TIBB) {
- BasicBlock *Dest = DestPHI->getParent();
-
- /// TIPHIValues - This array is lazily computed to determine the values of
- /// PHIs in Dest that TI would provide.
- SmallVector<Value*, 32> TIPHIValues;
-
- /// TIBBEntryNo - This is a cache to speed up pred queries for TIBB.
- unsigned TIBBEntryNo = 0;
-
- // Check to see if Dest has any blocks that can be used as a split edge for
- // this terminator.
- for (unsigned pi = 0, e = DestPHI->getNumIncomingValues(); pi != e; ++pi) {
- BasicBlock *Pred = DestPHI->getIncomingBlock(pi);
- // To be usable, the pred has to end with an uncond branch to the dest.
- BranchInst *PredBr = dyn_cast<BranchInst>(Pred->getTerminator());
- if (!PredBr || !PredBr->isUnconditional())
- continue;
- // Must be empty other than the branch and debug info.
- BasicBlock::iterator I = Pred->begin();
- while (isa<DbgInfoIntrinsic>(I))
- I++;
- if (&*I != PredBr)
- continue;
- // Cannot be the entry block; its label does not get emitted.
- if (Pred == &Dest->getParent()->getEntryBlock())
- continue;
-
- // Finally, since we know that Dest has phi nodes in it, we have to make
- // sure that jumping to Pred will have the same effect as going to Dest in
- // terms of PHI values.
- PHINode *PN;
- unsigned PHINo = 0;
- unsigned PredEntryNo = pi;
-
- bool FoundMatch = true;
- for (BasicBlock::iterator I = Dest->begin();
- (PN = dyn_cast<PHINode>(I)); ++I, ++PHINo) {
- if (PHINo == TIPHIValues.size()) {
- if (PN->getIncomingBlock(TIBBEntryNo) != TIBB)
- TIBBEntryNo = PN->getBasicBlockIndex(TIBB);
- TIPHIValues.push_back(PN->getIncomingValue(TIBBEntryNo));
- }
-
- // If the PHI entry doesn't work, we can't use this pred.
- if (PN->getIncomingBlock(PredEntryNo) != Pred)
- PredEntryNo = PN->getBasicBlockIndex(Pred);
-
- if (TIPHIValues[PHINo] != PN->getIncomingValue(PredEntryNo)) {
- FoundMatch = false;
- break;
- }
- }
-
- // If we found a workable predecessor, change TI to branch to Succ.
- if (FoundMatch)
- return Pred;
- }
- return 0;
-}
-
-
-/// SplitEdgeNicely - Split the critical edge from TI to its specified
-/// successor if it will improve codegen. We only do this if the successor has
-/// phi nodes (otherwise critical edges are ok). If there is already another
-/// predecessor of the succ that is empty (and thus has no phi nodes), use it
-/// instead of introducing a new block.
-static void SplitEdgeNicely(TerminatorInst *TI, unsigned SuccNum,
- SmallSet<std::pair<const BasicBlock*,
- const BasicBlock*>, 8> &BackEdges,
- Pass *P) {
- BasicBlock *TIBB = TI->getParent();
- BasicBlock *Dest = TI->getSuccessor(SuccNum);
- assert(isa<PHINode>(Dest->begin()) &&
- "This should only be called if Dest has a PHI!");
- PHINode *DestPHI = cast<PHINode>(Dest->begin());
-
- // Do not split edges to EH landing pads.
- if (InvokeInst *Invoke = dyn_cast<InvokeInst>(TI))
- if (Invoke->getSuccessor(1) == Dest)
- return;
-
- // As a hack, never split backedges of loops. Even though the copy for any
- // PHIs inserted on the backedge would be dead for exits from the loop, we
- // assume that the cost of *splitting* the backedge would be too high.
- if (BackEdges.count(std::make_pair(TIBB, Dest)))
- return;
-
- if (BasicBlock *ReuseBB = FindReusablePredBB(DestPHI, TIBB)) {
- ProfileInfo *PFI = P->getAnalysisIfAvailable<ProfileInfo>();
- if (PFI)
- PFI->splitEdge(TIBB, Dest, ReuseBB);
- Dest->removePredecessor(TIBB);
- TI->setSuccessor(SuccNum, ReuseBB);
- return;
- }
-
- SplitCriticalEdge(TI, SuccNum, P, true);
-}
-
-
/// OptimizeNoopCopyExpression - If the specified cast instruction is a noop
/// copy (e.g. it's casting from one pointer type to another, i32->i8 on PPC),
/// sink it into user blocks to reduce the number of virtual
@@ -1081,21 +967,8 @@
// across basic blocks and rewrite them to improve basic-block-at-a-time
// selection.
bool CodeGenPrepare::OptimizeBlock(BasicBlock &BB) {
- bool MadeChange = false;
-
- // Split all critical edges where the dest block has a PHI.
- if (CriticalEdgeSplit) {
- TerminatorInst *BBTI = BB.getTerminator();
- if (BBTI->getNumSuccessors() > 1 && !isa<IndirectBrInst>(BBTI)) {
- for (unsigned i = 0, e = BBTI->getNumSuccessors(); i != e; ++i) {
- BasicBlock *SuccBB = BBTI->getSuccessor(i);
- if (isa<PHINode>(SuccBB->begin()) && isCriticalEdge(BBTI, i, true))
- SplitEdgeNicely(BBTI, i, BackEdges, this);
- }
- }
- }
-
SunkAddrs.clear();
+ bool MadeChange = false;
CurInstIterator = BB.begin();
for (BasicBlock::iterator E = BB.end(); CurInstIterator != E; )
Modified: llvm/trunk/test/CodeGen/ARM/code-placement.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/code-placement.ll?rev=126825&r1=126824&r2=126825&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/code-placement.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/code-placement.ll Tue Mar 1 21:31:46 2011
@@ -1,4 +1,4 @@
-; RUN: llc < %s -mtriple=armv7-apple-darwin -cgp-critical-edge-splitting=0 | FileCheck %s
+; RUN: llc < %s -mtriple=armv7-apple-darwin | FileCheck %s
; PHI elimination shouldn't break backedge.
; rdar://8263994
Modified: llvm/trunk/test/CodeGen/X86/2010-09-30-CMOV-JumpTable-PHI.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/2010-09-30-CMOV-JumpTable-PHI.ll?rev=126825&r1=126824&r2=126825&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/2010-09-30-CMOV-JumpTable-PHI.ll (original)
+++ llvm/trunk/test/CodeGen/X86/2010-09-30-CMOV-JumpTable-PHI.ll Tue Mar 1 21:31:46 2011
@@ -1,4 +1,4 @@
-; RUN: llc -verify-machineinstrs -cgp-critical-edge-splitting=0 -mcpu=i386 < %s
+; RUN: llc -verify-machineinstrs -mcpu=i386 < %s
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32-n8:16:32"
target triple = "i386-pc-linux-gnu"
More information about the llvm-commits
mailing list