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InferAddressSpaces: Search constant expressions for addrspacecasts 

These are pretty common when using local memory, and the 64-bit generic
addressing is much more expensive to compute.

llvm-svn: 301711
This commit is contained in:
Matt Arsenault 2017-04-28 22:52:41 +00:00
parent e2f11690fe
commit e0f9e984fd
3 changed files with 68 additions and 15 deletions
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60
llvm/lib/Transforms/Scalar/InferAddressSpaces.cpp
View File

@ -138,7 +138,7 @@ private:
// Tries to infer the specific address space of each address expression in
// Postorder.
void inferAddressSpaces(const std::vector<Value *> &Postorder,
void inferAddressSpaces(ArrayRef<WeakVH> Postorder,
ValueToAddrSpaceMapTy *InferredAddrSpace) const;
bool isSafeToCastConstAddrSpace(Constant *C, unsigned NewAS) const;
@ -147,7 +147,7 @@ private:
// address spaces if InferredAddrSpace says so. Postorder is the postorder of
// all flat expressions in the use-def graph of function F.
bool
rewriteWithNewAddressSpaces(const std::vector<Value *> &Postorder,
rewriteWithNewAddressSpaces(ArrayRef<WeakVH> Postorder,
const ValueToAddrSpaceMapTy &InferredAddrSpace,
Function *F) const;
@ -162,7 +162,7 @@ private:
std::vector<std::pair<Value *, bool>> &PostorderStack,
DenseSet<Value *> &Visited) const;
std::vector<Value *> collectFlatAddressExpressions(Function &F) const;
std::vector<WeakVH> collectFlatAddressExpressions(Function &F) const;
Value *cloneValueWithNewAddressSpace(
Value *V, unsigned NewAddrSpace,
@ -274,16 +274,36 @@ void InferAddressSpaces::appendsFlatAddressExpressionToPostorderStack(
Value *V, std::vector<std::pair<Value *, bool>> &PostorderStack,
DenseSet<Value *> &Visited) const {
assert(V->getType()->isPointerTy());
// Generic addressing expressions may be hidden in nested constant
// expressions.
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
// TODO: Look in non-address parts, like icmp operands.
if (isAddressExpression(*CE) && Visited.insert(CE).second)
PostorderStack.push_back(std::make_pair(CE, false));
return;
}
if (isAddressExpression(*V) &&
V->getType()->getPointerAddressSpace() == FlatAddrSpace) {
if (Visited.insert(V).second)
if (Visited.insert(V).second) {
PostorderStack.push_back(std::make_pair(V, false));
Operator *Op = cast<Operator>(V);
for (unsigned I = 0, E = Op->getNumOperands(); I != E; ++I) {
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op->getOperand(I))) {
if (isAddressExpression(*CE) && Visited.insert(CE).second)
PostorderStack.emplace_back(CE, false);
}
}
}
}
}
// Returns all flat address expressions in function F. The elements are ordered
// ordered in postorder.
std::vector<Value *>
std::vector<WeakVH>
InferAddressSpaces::collectFlatAddressExpressions(Function &F) const {
// This function implements a non-recursive postorder traversal of a partial
// use-def graph of function F.
@ -332,18 +352,19 @@ InferAddressSpaces::collectFlatAddressExpressions(Function &F) const {
}
}
std::vector<Value *> Postorder; // The resultant postorder.
std::vector<WeakVH> Postorder; // The resultant postorder.
while (!PostorderStack.empty()) {
Value *TopVal = PostorderStack.back().first;
// If the operands of the expression on the top are already explored,
// adds that expression to the resultant postorder.
if (PostorderStack.back().second) {
Postorder.push_back(PostorderStack.back().first);
Postorder.push_back(TopVal);
PostorderStack.pop_back();
continue;
}
// Otherwise, adds its operands to the stack and explores them.
PostorderStack.back().second = true;
for (Value *PtrOperand : getPointerOperands(*PostorderStack.back().first)) {
for (Value *PtrOperand : getPointerOperands(*TopVal)) {
appendsFlatAddressExpressionToPostorderStack(PtrOperand, PostorderStack,
Visited);
}
@ -562,7 +583,7 @@ bool InferAddressSpaces::runOnFunction(Function &F) {
return false;
// Collects all flat address expressions in postorder.
std::vector<Value *> Postorder = collectFlatAddressExpressions(F);
std::vector<WeakVH> Postorder = collectFlatAddressExpressions(F);
// Runs a data-flow analysis to refine the address spaces of every expression
// in Postorder.
@ -574,8 +595,10 @@ bool InferAddressSpaces::runOnFunction(Function &F) {
return rewriteWithNewAddressSpaces(Postorder, InferredAddrSpace, &F);
}
// Constants need to be tracked through RAUW to handle cases with nested
// constant expressions, so wrap values in WeakVH.
void InferAddressSpaces::inferAddressSpaces(
const std::vector<Value *> &Postorder,
ArrayRef<WeakVH> Postorder,
ValueToAddrSpaceMapTy *InferredAddrSpace) const {
SetVector<Value *> Worklist(Postorder.begin(), Postorder.end());
// Initially, all expressions are in the uninitialized address space.
@ -787,7 +810,7 @@ static Value::use_iterator skipToNextUser(Value::use_iterator I,
}
bool InferAddressSpaces::rewriteWithNewAddressSpaces(
const std::vector<Value *> &Postorder,
ArrayRef<WeakVH> Postorder,
const ValueToAddrSpaceMapTy &InferredAddrSpace, Function *F) const {
// For each address expression to be modified, creates a clone of it with its
// pointer operands converted to the new address space. Since the pointer
@ -818,7 +841,9 @@ bool InferAddressSpaces::rewriteWithNewAddressSpaces(
SmallVector<Instruction *, 16> DeadInstructions;
// Replaces the uses of the old address expressions with the new ones.
for (Value *V : Postorder) {
for (const WeakVH &WVH : Postorder) {
assert(WVH && "value was unexpectedly deleted");
Value *V = WVH;
Value *NewV = ValueWithNewAddrSpace.lookup(V);
if (NewV == nullptr)
continue;
@ -826,6 +851,17 @@ bool InferAddressSpaces::rewriteWithNewAddressSpaces(
DEBUG(dbgs() << "Replacing the uses of " << *V
<< "\n with\n " << *NewV << '\n');
if (Constant *C = dyn_cast<Constant>(V)) {
Constant *Replace = ConstantExpr::getAddrSpaceCast(cast<Constant>(NewV),
C->getType());
if (C != Replace) {
DEBUG(dbgs() << "Inserting replacement const cast: "
<< Replace << ": " << *Replace << '\n');
C->replaceAllUsesWith(Replace);
V = Replace;
}
}
Value::use_iterator I, E, Next;
for (I = V->use_begin(), E = V->use_end(); I != E; ) {
Use &U = *I;

21
llvm/test/Transforms/InferAddressSpaces/AMDGPU/infer-getelementptr.ll
View File

@ -15,9 +15,8 @@ define void @simplified_constexpr_gep_addrspacecast(i64 %idx0, i64 %idx1) {
ret void
}
; FIXME: Should be able to eliminate inner constantexpr addrspacecast.
; CHECK-LABEL: @constexpr_gep_addrspacecast(
; CHECK: %gep0 = getelementptr inbounds double, double addrspace(3)* addrspacecast (double addrspace(4)* getelementptr ([648 x double], [648 x double] addrspace(4)* addrspacecast ([648 x double] addrspace(3)* @lds to [648 x double] addrspace(4)*), i64 0, i64 384) to double addrspace(3)*), i64 %idx0
; CHECK-NEXT: %gep0 = getelementptr inbounds double, double addrspace(3)* getelementptr inbounds ([648 x double], [648 x double] addrspace(3)* @lds, i64 0, i64 384), i64 %idx0
; CHECK-NEXT: store double 1.000000e+00, double addrspace(3)* %gep0, align 8
define void @constexpr_gep_addrspacecast(i64 %idx0, i64 %idx1) {
%gep0 = getelementptr inbounds double, double addrspace(4)* getelementptr ([648 x double], [648 x double] addrspace(4)* addrspacecast ([648 x double] addrspace(3)* @lds to [648 x double] addrspace(4)*), i64 0, i64 384), i64 %idx0
@ -54,3 +53,21 @@ define amdgpu_kernel void @vector_gep(<4 x [1024 x i32] addrspace(3)*> %array) n
store i32 99, i32 addrspace(4)* %p3
ret void
}
; CHECK-LABEL: @repeated_constexpr_gep_addrspacecast(
; CHECK-NEXT: %gep0 = getelementptr inbounds double, double addrspace(3)* getelementptr inbounds ([648 x double], [648 x double] addrspace(3)* @lds, i64 0, i64 384), i64 %idx0
; CHECK-NEXT: store double 1.000000e+00, double addrspace(3)* %gep0, align 8
; CHECK-NEXT: %gep1 = getelementptr inbounds double, double addrspace(3)* getelementptr inbounds ([648 x double], [648 x double] addrspace(3)* @lds, i64 0, i64 384), i64 %idx1
; CHECK-NEXT: store double 1.000000e+00, double addrspace(3)* %gep1, align 8
; CHECK-NEXT: ret void
define void @repeated_constexpr_gep_addrspacecast(i64 %idx0, i64 %idx1) {
%gep0 = getelementptr inbounds double, double addrspace(4)* getelementptr ([648 x double], [648 x double] addrspace(4)* addrspacecast ([648 x double] addrspace(3)* @lds to [648 x double] addrspace(4)*), i64 0, i64 384), i64 %idx0
%asc0 = addrspacecast double addrspace(4)* %gep0 to double addrspace(3)*
store double 1.0, double addrspace(3)* %asc0, align 8
%gep1 = getelementptr inbounds double, double addrspace(4)* getelementptr ([648 x double], [648 x double] addrspace(4)* addrspacecast ([648 x double] addrspace(3)* @lds to [648 x double] addrspace(4)*), i64 0, i64 384), i64 %idx1
%asc1 = addrspacecast double addrspace(4)* %gep1 to double addrspace(3)*
store double 1.0, double addrspace(3)* %asc1, align 8
ret void
}

2
llvm/test/Transforms/InferAddressSpaces/NVPTX/bug31948.ll
View File

@ -10,7 +10,7 @@ target datalayout = "e-i64:64-v16:16-v32:32-n16:32:64"
; CHECK: %tmp = load float*, float* addrspace(3)* getelementptr inbounds (%struct.bar, %struct.bar addrspace(3)* @var1, i64 0, i32 1), align 8
; CHECK: %tmp1 = load float, float* %tmp, align 4
; CHECK: store float %conv1, float* %tmp, align 4
; CHECK: store i32 32, i32 addrspace(3)* addrspacecast (i32* bitcast (float** getelementptr (%struct.bar, %struct.bar* addrspacecast (%struct.bar addrspace(3)* @var1 to %struct.bar*), i64 0, i32 1) to i32*) to i32 addrspace(3)*), align 4
; CHECK: store i32 32, i32 addrspace(3)* bitcast (float* addrspace(3)* getelementptr inbounds (%struct.bar, %struct.bar addrspace(3)* @var1, i64 0, i32 1) to i32 addrspace(3)*), align 4
define void @bug31948(float %a, float* nocapture readnone %x, float* nocapture readnone %y) local_unnamed_addr #0 {
entry:
%tmp = load float*, float** getelementptr (%struct.bar, %struct.bar* addrspacecast (%struct.bar addrspace(3)* @var1 to %struct.bar*), i64 0, i32 1), align 8