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Merged
jayfurmanek merged 1 commit into from
Apr 1, 2026
Merged

[AMD] CanonicalizePointers: Handle different base pointers and offset… #935

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45 changes: 45 additions & 0 deletions test/TritonGPU/amd/amd-canonicalize-pointers-different-bases.mlir
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Original file line number Diff line number Diff line change
@@ -0,0 +1,45 @@
// RUN: triton-opt %s -split-input-file -tritonamdgpu-canonicalize-pointers -canonicalize | FileCheck %s

// CHECK-LABEL: tt.func @scf_if_different_bases
// CHECK: [[BASE:%.*]] = arith.select %arg2, %arg0, %arg1 : !tt.ptr<f32>
// CHECK: [[OFFSET:%.*]] = arith.select %arg2, %c16_i32, %c32_i32 : i32
// CHECK: [[PTR:%.*]] = tt.addptr [[BASE]], [[OFFSET]]
// CHECK: tt.load [[PTR]]
module attributes {"ttg.num-warps" = 4 : i32} {
tt.func @scf_if_different_bases(%arg0: !tt.ptr<f32> {tt.divisibility = 16 : i32, tt.pointer_range = 32 : i32},
%arg1: !tt.ptr<f32> {tt.divisibility = 16 : i32, tt.pointer_range = 32 : i32},
%arg2: i1) -> f32 {
%c16_i32 = arith.constant 16 : i32
%c32_i32 = arith.constant 32 : i32
%0 = scf.if %arg2 -> (!tt.ptr<f32>) {
%2 = tt.addptr %arg0, %c16_i32 : !tt.ptr<f32>, i32
scf.yield %2 : !tt.ptr<f32>
} else {
%2 = tt.addptr %arg1, %c32_i32 : !tt.ptr<f32>, i32
scf.yield %2 : !tt.ptr<f32>
}
%1 = tt.load %0 : !tt.ptr<f32>
tt.return %1 : f32
}
}

// -----

// CHECK-LABEL: tt.func @select_different_bases
// CHECK: [[BASE:%.*]] = arith.select %arg2, %arg0, %arg1 : !tt.ptr<f32>
// CHECK: [[OFFSET:%.*]] = arith.select %arg2, %c16_i32, %c32_i32 : i32
// CHECK: [[PTR:%.*]] = tt.addptr [[BASE]], [[OFFSET]]
// CHECK: tt.load [[PTR]]
module attributes {"ttg.num-warps" = 4 : i32} {
tt.func @select_different_bases(%arg0: !tt.ptr<f32> {tt.divisibility = 16 : i32, tt.pointer_range = 32 : i32},
%arg1: !tt.ptr<f32> {tt.divisibility = 16 : i32, tt.pointer_range = 32 : i32},
%arg2: i1) -> f32 {
%c16_i32 = arith.constant 16 : i32
%c32_i32 = arith.constant 32 : i32
%2 = tt.addptr %arg0, %c16_i32 : !tt.ptr<f32>, i32
%3 = tt.addptr %arg1, %c32_i32 : !tt.ptr<f32>, i32
%4 = arith.select %arg2, %2, %3 : !tt.ptr<f32>
%5 = tt.load %4 : !tt.ptr<f32>
tt.return %5 : f32
}
}
73 changes: 36 additions & 37 deletions third_party/amd/lib/TritonAMDGPUTransforms/CanonicalizePointers.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -462,18 +462,29 @@ struct FatPointers {

friend bool operator==(const FatPtrAttrs &lhs, const FatPtrAttrs &rhs) {
return lhs.canNarrow == rhs.canNarrow &&
lhs.attributes == rhs.attributes &&
lhs.smallTensorBase == rhs.smallTensorBase;
lhs.isSmallTensor == rhs.isSmallTensor &&
lhs.attributes.getArrayRef() == rhs.attributes.getArrayRef();
}

friend bool operator!=(const FatPtrAttrs &lhs, const FatPtrAttrs &rhs) {
return !(lhs == rhs);
}

llvm::DenseMap<StringRef, Attribute> attributes;
// If the fat-pointer points to somewhere in a small-tensor, keep track the
// base of the tensor.
Value smallTensorBase;
static FatPtrAttrs intersect(const FatPtrAttrs &lhs,
const FatPtrAttrs &rhs) {
FatPtrAttrs result;
result.canNarrow = lhs.canNarrow && rhs.canNarrow;
result.isSmallTensor = lhs.isSmallTensor && rhs.isSmallTensor;
for (const auto &attr : lhs.attributes) {
auto it = rhs.attributes.find(attr.first);
if (it != rhs.attributes.end() && it->second == attr.second)
result.attributes[attr.first] = attr.second;
}
return result;
}

llvm::SmallMapVector<StringRef, Attribute, 2> attributes;
bool isSmallTensor = false;
bool canNarrow = false;
};

Expand Down Expand Up @@ -563,7 +574,7 @@ Value createTensorPointer(RewriterBase &rewriter, Value basePtr, Value offset,
auto addPtrOp =
tt::AddPtrOp::create(rewriter, loc, basePtr.getType(), basePtr, offset);
for (const auto &attribute : fatPtrAttrs.attributes)
addPtrOp->setAttr(attribute.getFirst(), attribute.getSecond());
addPtrOp->setAttr(attribute.first, attribute.second);
return addPtrOp.getResult();
}

Expand All @@ -585,7 +596,7 @@ Value createTensorPointer(RewriterBase &rewriter, Value basePtr, Value offset,
tt::AddPtrOp::create(rewriter, loc, tensorPtrType, tensorPtr, offset);

for (const auto &attribute : fatPtrAttrs.attributes)
addPtrOp->setAttr(attribute.getFirst(), attribute.getSecond());
addPtrOp->setAttr(attribute.first, attribute.second);
return addPtrOp.getResult();
}

Expand Down Expand Up @@ -745,7 +756,7 @@ class ConvertAddPtrOp : public PointerCanonicalizationPattern<tt::AddPtrOp> {
RewriterBase::InsertionGuard guard(rewriter);
rewriter.setInsertionPoint(addPtrOp);

if (fatPtrs.at({fatPtrBase, fatPtrOffset}).smallTensorBase)
if (fatPtrs.at({fatPtrBase, fatPtrOffset}).isSmallTensor)
return rewriteSmallTensorPtr(addPtrOp, adaptor, rewriter);

// Query all discardable attributes that we want to preserve
Expand Down Expand Up @@ -861,7 +872,7 @@ class ConvertAddPtrOp : public PointerCanonicalizationPattern<tt::AddPtrOp> {
const auto &oldAttr = fatPtrs.at({fatPtrBase, fatPtrOffset});

LDBG("smal-tensor addPtr: " << addPtrOp);
LDBG(" - with tensor-base: " << oldAttr.smallTensorBase);
LDBG(" - isSmallTensor: " << oldAttr.isSmallTensor);
LDBG(" - with originl offset: " << origOffset);
LDBG(" - fatPtr base: " << fatPtrBase);
LDBG(" - fatPtr offst: " << fatPtrOffset);
Expand Down Expand Up @@ -1351,17 +1362,6 @@ class ConvertArithSelectOp
// select of base and offset
ValueRange fatPtrFalse = adaptor.getFalseValue();
ValueRange fatPtrTrue = adaptor.getTrueValue();
// Simple case of a scalar select: update the base pointer
if (!isa<RankedTensorType>(selectOp.getType())) {
auto newSelectOp = arith::SelectOp::create(
rewriter, selectOp.getLoc(), selectOp.getType(),
selectOp.getCondition(), fatPtrTrue[0], selectOp.getFalseValue());
rewriter.replaceOpWithMultiple(selectOp, {{newSelectOp, fatPtrTrue[1]}});
fatPtrs[{newSelectOp, /*fatPtrOffset*/ fatPtrTrue[1]}] =
fatPtrs.at({fatPtrTrue[0], fatPtrTrue[1]});
return success();
}

// Rewrite to select(fatBaseT, fatBaseF) and select(fatOffsetT, fatOffsetF)
auto newBase = arith::SelectOp::create(rewriter, selectOp.getLoc(),
selectOp.getCondition(),
Expand All @@ -1370,12 +1370,10 @@ class ConvertArithSelectOp
selectOp.getCondition(),
fatPtrTrue[1], fatPtrFalse[1]);

assert((fatPtrs.at({fatPtrTrue[0], fatPtrTrue[1]}) ==
fatPtrs.at({fatPtrFalse[0], fatPtrFalse[1]})) &&
"expected can narrow to be the same for both fatPtrT and fatPtrF");

rewriter.replaceOpWithMultiple(selectOp, {{newBase, newOffset}});
fatPtrs[{newBase, newOffset}] = fatPtrs.at({fatPtrTrue[0], fatPtrTrue[1]});
fatPtrs[{newBase, newOffset}] = FatPointers::FatPtrAttrs::intersect(
fatPtrs.at({fatPtrTrue[0], fatPtrTrue[1]}),
fatPtrs.at({fatPtrFalse[0], fatPtrFalse[1]}));

return success();
}
Expand Down Expand Up @@ -1423,14 +1421,6 @@ class ConvertSCFIfOp : public PointerCanonicalizationPattern<scf::IfOp> {
assert(i < ifOp.thenYield().getNumOperands() &&
i + 1 < ifOp.thenYield().getNumOperands() &&
"expected idx to be within bounds of IfOp's results");
Value thenFatPtrBase = ifOp.thenYield().getOperand(i);
Value thenFatPtrOffset = ifOp.thenYield().getOperand(i + 1);
Value elseFatPtrBase = ifOp.elseYield().getOperand(i);
Value elseFatPtrOffset = ifOp.elseYield().getOperand(i + 1);
assert((fatPtrs.at({thenFatPtrBase, thenFatPtrOffset}) ==
fatPtrs.at({elseFatPtrBase, elseFatPtrOffset})) &&
"expected then fat ptr canNarrow and else fat ptr canNarrow "
"to be equal");
}
}
}
Expand All @@ -1456,8 +1446,17 @@ class ConvertSCFIfOp : public PointerCanonicalizationPattern<scf::IfOp> {
for (int64_t idx : yieldPtrOffsets) {
Value thenFatPtrBase = newIfOp.thenYield().getOperand(idx);
Value thenFatPtrOffset = newIfOp.thenYield().getOperand(idx + 1);
fatPtrs[{newIfOp.getResult(idx), newIfOp.getResult(idx + 1)}] =
fatPtrs.at({thenFatPtrBase, thenFatPtrOffset});
const auto &thenAttrs = fatPtrs.at({thenFatPtrBase, thenFatPtrOffset});
if (withElseRegion) {
Value elseFatPtrBase = newIfOp.elseYield().getOperand(idx);
Value elseFatPtrOffset = newIfOp.elseYield().getOperand(idx + 1);
const auto &elseAttrs = fatPtrs.at({elseFatPtrBase, elseFatPtrOffset});
fatPtrs[{newIfOp.getResult(idx), newIfOp.getResult(idx + 1)}] =
FatPointers::FatPtrAttrs::intersect(thenAttrs, elseAttrs);
} else {
fatPtrs[{newIfOp.getResult(idx), newIfOp.getResult(idx + 1)}] =
thenAttrs;
}
}

ResultRange results = newIfOp.getResults();
Expand Down Expand Up @@ -1697,7 +1696,7 @@ struct InitFuncPtrArgs : OpRewritePattern<tt::FuncOp> {
rewriter.replaceAllUsesExcept(arg, dummyCast.getResult(0), dummyCast);
fatPtrs[{arg, zeroOffset}].canNarrow = true;
if (bitness != 64)
fatPtrs[{arg, zeroOffset}].smallTensorBase = arg;
fatPtrs[{arg, zeroOffset}].isSmallTensor = true;
}

newOp->setDiscardableAttr(kInitFuncArgsRewritten, rewriter.getUnitAttr());
Expand Down
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