[llvm-commits] [llvm] r90013 - in /llvm/trunk: lib/Analysis/MemoryDependenceAnalysis.cpp test/Transforms/GVN/pre-load.ll
Chris Lattner
sabre at nondot.org
Fri Nov 27 11:11:32 PST 2009
Author: lattner
Date: Fri Nov 27 13:11:31 2009
New Revision: 90013
URL: http://llvm.org/viewvc/llvm-project?rev=90013&view=rev
Log:
add support for recursive phi translation and phi
translation of add with immediate. This allows us
to optimize this function:
void test(int N, double* G) {
long j;
G[1] = 1;
for (j = 1; j < N - 1; j++)
G[j+1] = G[j] + G[j+1];
}
to only do one load every iteration of the loop.
Modified:
llvm/trunk/lib/Analysis/MemoryDependenceAnalysis.cpp
llvm/trunk/test/Transforms/GVN/pre-load.ll
Modified: llvm/trunk/lib/Analysis/MemoryDependenceAnalysis.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/MemoryDependenceAnalysis.cpp?rev=90013&r1=90012&r2=90013&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/MemoryDependenceAnalysis.cpp (original)
+++ llvm/trunk/lib/Analysis/MemoryDependenceAnalysis.cpp Fri Nov 27 13:11:31 2009
@@ -694,17 +694,31 @@
// We can handle bitcast of a PHI, but the PHI needs to be in the same block
// as the bitcast.
if (BitCastInst *BC = dyn_cast<BitCastInst>(Inst))
+ // FIXME: Allow any phi translatable operand.
if (PHINode *PN = dyn_cast<PHINode>(BC->getOperand(0)))
if (PN->getParent() == BC->getParent())
return true;
- // We can translate a GEP that uses a PHI in the current block for at least
- // one of its operands.
+ // We can translate a GEP if all of its operands defined in this block are phi
+ // translatable.
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Inst)) {
- for (unsigned i = 0, e = GEP->getNumOperands(); i != e; ++i)
- if (PHINode *PN = dyn_cast<PHINode>(GEP->getOperand(i)))
- if (PN->getParent() == GEP->getParent())
- return true;
+ for (unsigned i = 0, e = GEP->getNumOperands(); i != e; ++i) {
+ Instruction *GEPOpI = dyn_cast<Instruction>(GEP->getOperand(i));
+ if (GEPOpI == 0 || GEPOpI->getParent() != Inst->getParent())
+ continue;
+
+ if (!isPHITranslatable(GEPOpI))
+ return false;
+ }
+ return true;
+ }
+
+ if (Inst->getOpcode() == Instruction::Add &&
+ isa<ConstantInt>(Inst->getOperand(1))) {
+ Instruction *GEPOpI = dyn_cast<Instruction>(Inst->getOperand(0));
+ if (GEPOpI == 0 || GEPOpI->getParent() != Inst->getParent())
+ return true;
+ return isPHITranslatable(GEPOpI);
}
// cerr << "MEMDEP: Could not PHI translate: " << *Pointer;
@@ -731,6 +745,7 @@
// Handle bitcast of PHI.
if (BitCastInst *BC = dyn_cast<BitCastInst>(Inst)) {
+ // FIXME: Recurse!
PHINode *BCPN = cast<PHINode>(BC->getOperand(0));
Value *PHIIn = BCPN->getIncomingValueForBlock(Pred);
@@ -749,7 +764,7 @@
return 0;
}
- // Handle getelementptr with at least one PHI operand.
+ // Handle getelementptr with at least one PHI translatable operand.
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Inst)) {
SmallVector<Value*, 8> GEPOps;
BasicBlock *CurBB = GEP->getParent();
@@ -764,8 +779,8 @@
}
// If the operand is a phi node, do phi translation.
- if (PHINode *PN = dyn_cast<PHINode>(GEPOp)) {
- GEPOps.push_back(PN->getIncomingValueForBlock(Pred));
+ if (Value *InOp = PHITranslatePointer(GEPOp, CurBB, Pred, TD)) {
+ GEPOps.push_back(InOp);
continue;
}
@@ -778,7 +793,6 @@
if (Value *V = SimplifyGEPInst(&GEPOps[0], GEPOps.size(), TD))
return V;
-
// Scan to see if we have this GEP available.
Value *APHIOp = GEPOps[0];
for (Value::use_iterator UI = APHIOp->use_begin(), E = APHIOp->use_end();
@@ -800,6 +814,49 @@
return 0;
}
+ // Handle add with a constant RHS.
+ if (Inst->getOpcode() == Instruction::Add &&
+ isa<ConstantInt>(Inst->getOperand(1))) {
+ // PHI translate the LHS.
+ Value *LHS;
+ Constant *RHS = cast<ConstantInt>(Inst->getOperand(1));
+ Instruction *OpI = dyn_cast<Instruction>(Inst->getOperand(0));
+ bool isNSW = cast<BinaryOperator>(Inst)->hasNoSignedWrap();
+ bool isNUW = cast<BinaryOperator>(Inst)->hasNoUnsignedWrap();
+
+ if (OpI == 0 || OpI->getParent() != Inst->getParent())
+ LHS = Inst->getOperand(0);
+ else {
+ LHS = PHITranslatePointer(Inst->getOperand(0), CurBB, Pred, TD);
+ if (LHS == 0)
+ return 0;
+ }
+
+ // If the PHI translated LHS is an add of a constant, fold the immediates.
+ if (BinaryOperator *BOp = dyn_cast<BinaryOperator>(LHS))
+ if (BOp->getOpcode() == Instruction::Add)
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(BOp->getOperand(1))) {
+ LHS = BOp->getOperand(0);
+ RHS = ConstantExpr::getAdd(RHS, CI);
+ isNSW = isNUW = false;
+ }
+
+ // See if the add simplifies away.
+ if (Value *Res = SimplifyAddInst(LHS, RHS, isNSW, isNUW, TD))
+ return Res;
+
+ // Otherwise, see if we have this add available somewhere.
+ for (Value::use_iterator UI = LHS->use_begin(), E = LHS->use_end();
+ UI != E; ++UI) {
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(*UI))
+ if (BO->getOperand(0) == LHS && BO->getOperand(1) == RHS &&
+ BO->getParent()->getParent() == CurBB->getParent())
+ return BO;
+ }
+
+ return 0;
+ }
+
return 0;
}
Modified: llvm/trunk/test/Transforms/GVN/pre-load.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/GVN/pre-load.ll?rev=90013&r1=90012&r2=90013&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/GVN/pre-load.ll (original)
+++ llvm/trunk/test/Transforms/GVN/pre-load.ll Fri Nov 27 13:11:31 2009
@@ -195,6 +195,49 @@
ret void
}
+;void test7(int N, double* G) {
+; long j;
+; G[1] = 1;
+; for (j = 1; j < N - 1; j++)
+; G[j+1] = G[j] + G[j+1];
+;}
+
+; This requires phi translation of the adds.
+define void @test7(i32 %N, double* nocapture %G) nounwind ssp {
+entry:
+ %0 = getelementptr inbounds double* %G, i64 1
+ store double 1.000000e+00, double* %0, align 8
+ %1 = add i32 %N, -1
+ %2 = icmp sgt i32 %1, 1
+ br i1 %2, label %bb.nph, label %return
+
+bb.nph:
+ %tmp = sext i32 %1 to i64
+ %tmp7 = add i64 %tmp, -1
+ br label %bb
+
+bb:
+ %indvar = phi i64 [ 0, %bb.nph ], [ %tmp9, %bb ]
+ %tmp8 = add i64 %indvar, 2
+ %scevgep = getelementptr double* %G, i64 %tmp8
+ %tmp9 = add i64 %indvar, 1
+ %scevgep10 = getelementptr double* %G, i64 %tmp9
+ %3 = load double* %scevgep10, align 8
+ %4 = load double* %scevgep, align 8
+ %5 = fadd double %3, %4
+ store double %5, double* %scevgep, align 8
+ %exitcond = icmp eq i64 %tmp9, %tmp7
+ br i1 %exitcond, label %return, label %bb
+
+; Should only be one load in the loop.
+; CHECK: bb:
+; CHECK: load double*
+; CHECK-NOT: load double*
+; CHECK: br i1 %exitcond
+
+return:
+ ret void
+}
;;; --- todo
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