[llvm] r274094 - Revert "[InstCombine] Avoid combining the bitcast of a var that is used as both address and result of load instructions"
Eric Christopher via llvm-commits
llvm-commits at lists.llvm.org
Tue Jun 28 20:05:58 PDT 2016
Author: echristo
Date: Tue Jun 28 22:05:58 2016
New Revision: 274094
URL: http://llvm.org/viewvc/llvm-project?rev=274094&view=rev
Log:
Revert "[InstCombine] Avoid combining the bitcast of a var that is used as both address and result of load instructions"
Revert "[InstCombine] Combine A->B->A BitCast"
as this appears to cause PR27996 and as discussed in http://reviews.llvm.org/D20847
This reverts commits r270135 and r263734.
Removed:
llvm/trunk/test/Transforms/InstCombine/pr25342.ll
llvm/trunk/test/Transforms/InstCombine/pr27703.ll
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp
llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp?rev=274094&r1=274093&r2=274094&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp Tue Jun 28 22:05:58 2016
@@ -12,7 +12,6 @@
//===----------------------------------------------------------------------===//
#include "InstCombineInternal.h"
-#include "llvm/ADT/SetVector.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/PatternMatch.h"
@@ -1790,113 +1789,6 @@ static Instruction *canonicalizeBitCastE
return ExtractElementInst::Create(NewBC, ExtElt->getIndexOperand());
}
-/// This function handles following case
-///
-/// A -> B cast
-/// PHI
-/// B -> A cast
-///
-/// All the related PHI nodes can be replaced by new PHI nodes with type A.
-/// The uses of \p CI can be changed to the new PHI node corresponding to \p PN.
-Instruction *InstCombiner::optimizeBitCastFromPhi(CastInst &CI, PHINode *PN) {
- Value *Src = CI.getOperand(0);
- Type *SrcTy = Src->getType(); // Type B
- Type *DestTy = CI.getType(); // Type A
-
- SmallVector<PHINode *, 4> PhiWorklist;
- SmallSetVector<PHINode *, 4> OldPhiNodes;
-
- // Find all of the A->B casts and PHI nodes.
- // We need to inpect all related PHI nodes, but PHIs can be cyclic, so
- // OldPhiNodes is used to track all known PHI nodes, before adding a new
- // PHI to PhiWorklist, it is checked against and added to OldPhiNodes first.
- PhiWorklist.push_back(PN);
- OldPhiNodes.insert(PN);
- while (!PhiWorklist.empty()) {
- auto *OldPN = PhiWorklist.pop_back_val();
- for (Value *IncValue : OldPN->incoming_values()) {
- if (isa<Constant>(IncValue))
- continue;
-
- auto *LI = dyn_cast<LoadInst>(IncValue);
- if (LI) {
- // If there is a sequence of one or more load instructions, each loaded
- // value is used as address of later load instruction, bitcast is
- // necessary to change the value type, don't optimize it. For
- // simplicity we give up if the load address comes from another load.
- Value *Addr = LI->getOperand(0);
- if (Addr == &CI || isa<LoadInst>(Addr))
- return nullptr;
- if (LI->hasOneUse() && LI->isSimple())
- continue;
- // If a LoadInst has more than one use, changing the type of loaded
- // value may create another bitcast.
- return nullptr;
- }
-
- auto *PNode = dyn_cast<PHINode>(IncValue);
- if (PNode) {
- if (OldPhiNodes.insert(PNode))
- PhiWorklist.push_back(PNode);
- continue;
- }
-
- auto *BCI = dyn_cast<BitCastInst>(IncValue);
- // We can't handle other instructions.
- if (!BCI)
- return nullptr;
-
- // Verify it's a A->B cast.
- Type *TyA = BCI->getOperand(0)->getType();
- Type *TyB = BCI->getType();
- if (TyA != DestTy || TyB != SrcTy)
- return nullptr;
- }
- }
-
- // For each old PHI node, create a corresponding new PHI node with a type A.
- SmallDenseMap<PHINode *, PHINode *> NewPNodes;
- for (auto *OldPN : OldPhiNodes) {
- Builder->SetInsertPoint(OldPN);
- PHINode *NewPN = Builder->CreatePHI(DestTy, OldPN->getNumOperands());
- NewPNodes[OldPN] = NewPN;
- }
-
- // Fill in the operands of new PHI nodes.
- for (auto *OldPN : OldPhiNodes) {
- PHINode *NewPN = NewPNodes[OldPN];
- for (unsigned j = 0, e = OldPN->getNumOperands(); j != e; ++j) {
- Value *V = OldPN->getOperand(j);
- Value *NewV = nullptr;
- if (auto *C = dyn_cast<Constant>(V)) {
- NewV = Builder->CreateBitCast(C, DestTy);
- } else if (auto *LI = dyn_cast<LoadInst>(V)) {
- Builder->SetInsertPoint(OldPN->getIncomingBlock(j)->getTerminator());
- NewV = Builder->CreateBitCast(LI, DestTy);
- Worklist.Add(LI);
- } else if (auto *BCI = dyn_cast<BitCastInst>(V)) {
- NewV = BCI->getOperand(0);
- } else if (auto *PrevPN = dyn_cast<PHINode>(V)) {
- NewV = NewPNodes[PrevPN];
- }
- assert(NewV);
- NewPN->addIncoming(NewV, OldPN->getIncomingBlock(j));
- }
- }
-
- // If there is a store with type B, change it to type A.
- for (User *U : PN->users()) {
- auto *SI = dyn_cast<StoreInst>(U);
- if (SI && SI->isSimple() && SI->getOperand(0) == PN) {
- Builder->SetInsertPoint(SI);
- SI->setOperand(0, Builder->CreateBitCast(NewPNodes[PN], SrcTy));
- Worklist.Add(SI);
- }
- }
-
- return replaceInstUsesWith(CI, NewPNodes[PN]);
-}
-
Instruction *InstCombiner::visitBitCast(BitCastInst &CI) {
// If the operands are integer typed then apply the integer transforms,
// otherwise just apply the common ones.
@@ -2020,11 +1912,6 @@ Instruction *InstCombiner::visitBitCast(
}
}
- // Handle the A->B->A cast, and there is an intervening PHI node.
- if (PHINode *PN = dyn_cast<PHINode>(Src))
- if (Instruction *I = optimizeBitCastFromPhi(CI, PN))
- return I;
-
if (Instruction *I = canonicalizeBitCastExtElt(CI, *this, DL))
return I;
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h?rev=274094&r1=274093&r2=274094&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h Tue Jun 28 22:05:58 2016
@@ -396,7 +396,6 @@ private:
Instruction *scalarizePHI(ExtractElementInst &EI, PHINode *PN);
Value *EvaluateInDifferentElementOrder(Value *V, ArrayRef<int> Mask);
Instruction *foldCastedBitwiseLogic(BinaryOperator &I);
- Instruction *optimizeBitCastFromPhi(CastInst &CI, PHINode *PN);
public:
/// \brief Inserts an instruction \p New before instruction \p Old
Removed: llvm/trunk/test/Transforms/InstCombine/pr25342.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/pr25342.ll?rev=274093&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/pr25342.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/pr25342.ll (removed)
@@ -1,93 +0,0 @@
-; RUN: opt < %s -instcombine -S | FileCheck %s
-
-%"struct.std::complex" = type { { float, float } }
- at dd = external global %"struct.std::complex", align 4
- at dd2 = external global %"struct.std::complex", align 4
-
-define void @_Z3fooi(i32 signext %n) {
-entry:
- br label %for.cond
-
-for.cond:
- %ldd.sroa.0.0 = phi i32 [ 0, %entry ], [ %5, %for.body ]
- %ldd.sroa.6.0 = phi i32 [ 0, %entry ], [ %7, %for.body ]
- %i.0 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
- %cmp = icmp slt i32 %i.0, %n
- br i1 %cmp, label %for.body, label %for.end
-
-for.body:
- %0 = load float, float* getelementptr inbounds (%"struct.std::complex", %"struct.std::complex"* @dd, i64 0, i32 0, i32 0), align 4
- %1 = load float, float* getelementptr inbounds (%"struct.std::complex", %"struct.std::complex"* @dd, i64 0, i32 0, i32 1), align 4
- %2 = load float, float* getelementptr inbounds (%"struct.std::complex", %"struct.std::complex"* @dd2, i64 0, i32 0, i32 0), align 4
- %3 = load float, float* getelementptr inbounds (%"struct.std::complex", %"struct.std::complex"* @dd2, i64 0, i32 0, i32 1), align 4
- %mul.i = fmul float %0, %2
- %mul4.i = fmul float %1, %3
- %sub.i = fsub float %mul.i, %mul4.i
- %mul5.i = fmul float %1, %2
- %mul6.i = fmul float %0, %3
- %add.i4 = fadd float %mul5.i, %mul6.i
- %4 = bitcast i32 %ldd.sroa.0.0 to float
- %add.i = fadd float %sub.i, %4
- %5 = bitcast float %add.i to i32
- %6 = bitcast i32 %ldd.sroa.6.0 to float
- %add4.i = fadd float %add.i4, %6
- %7 = bitcast float %add4.i to i32
- %inc = add nsw i32 %i.0, 1
- br label %for.cond
-
-for.end:
- store i32 %ldd.sroa.0.0, i32* bitcast (%"struct.std::complex"* @dd to i32*), align 4
- store i32 %ldd.sroa.6.0, i32* bitcast (float* getelementptr inbounds (%"struct.std::complex", %"struct.std::complex"* @dd, i64 0, i32 0, i32 1) to i32*), align 4
- ret void
-
-; CHECK: phi float
-; CHECK: store float
-; CHECK-NOT: bitcast
-}
-
-
-define void @multi_phi(i32 signext %n) {
-entry:
- br label %for.cond
-
-for.cond:
- %ldd.sroa.0.0 = phi i32 [ 0, %entry ], [ %9, %odd.bb ]
- %i.0 = phi i32 [ 0, %entry ], [ %inc, %odd.bb ]
- %cmp = icmp slt i32 %i.0, %n
- br i1 %cmp, label %for.body, label %for.end
-
-for.body:
- %0 = load float, float* getelementptr inbounds (%"struct.std::complex", %"struct.std::complex"* @dd, i64 0, i32 0, i32 0), align 4
- %1 = load float, float* getelementptr inbounds (%"struct.std::complex", %"struct.std::complex"* @dd, i64 0, i32 0, i32 1), align 4
- %2 = load float, float* getelementptr inbounds (%"struct.std::complex", %"struct.std::complex"* @dd2, i64 0, i32 0, i32 0), align 4
- %3 = load float, float* getelementptr inbounds (%"struct.std::complex", %"struct.std::complex"* @dd2, i64 0, i32 0, i32 1), align 4
- %mul.i = fmul float %0, %2
- %mul4.i = fmul float %1, %3
- %sub.i = fsub float %mul.i, %mul4.i
- %4 = bitcast i32 %ldd.sroa.0.0 to float
- %add.i = fadd float %sub.i, %4
- %5 = bitcast float %add.i to i32
- %inc = add nsw i32 %i.0, 1
- %bit0 = and i32 %inc, 1
- %even = icmp slt i32 %bit0, 1
- br i1 %even, label %even.bb, label %odd.bb
-
-even.bb:
- %6 = bitcast i32 %5 to float
- %7 = fadd float %sub.i, %6
- %8 = bitcast float %7 to i32
- br label %odd.bb
-
-odd.bb:
- %9 = phi i32 [ %5, %for.body ], [ %8, %even.bb ]
- br label %for.cond
-
-for.end:
- store i32 %ldd.sroa.0.0, i32* bitcast (%"struct.std::complex"* @dd to i32*), align 4
- ret void
-
-; CHECK-LABEL: @multi_phi(
-; CHECK: phi float
-; CHECK: store float
-; CHECK-NOT: bitcast
-}
Removed: llvm/trunk/test/Transforms/InstCombine/pr27703.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/pr27703.ll?rev=274093&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/pr27703.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/pr27703.ll (removed)
@@ -1,20 +0,0 @@
-; RUN: opt < %s -instcombine -S | FileCheck %s
-
-define void @mem() {
-bb:
- br label %bb6
-
-bb6:
- %.0 = phi i8** [ undef, %bb ], [ %t2, %bb6 ]
- %tmp = load i8*, i8** %.0, align 8
- %bc = bitcast i8* %tmp to i8**
- %t1 = load i8*, i8** %bc, align 8
- %t2 = bitcast i8* %t1 to i8**
- br label %bb6
-
-bb206:
- ret void
-; CHECK: phi
-; CHECK: bitcast
-; CHECK: load
-}
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