[Matrix] Use data layout index type for lowering matrix intrinsics (llvm#162646)

To properly support the matrix intrinsics on, e.g., 32-bit platforms
(without the need to emit `libc` calls), `LowerMatrixIntrinsics` pass
should generate code that performs strided index calculations using the
same pointer bit-width as the matrix pointers, as determined by the data
layout. This patch updates the `LowerMatrixInstrics` transform to make
this the case.

PR: llvm#162646

Author: cofibrant

llvm/docs/LangRef.rst

@@ -21074,12 +21074,12 @@ Overview:
 
 The '``llvm.matrix.column.major.load.*``' intrinsics load a ``<Rows> x <Cols>``
 matrix using a stride of ``%Stride`` to compute the start address of the
-different columns.  The offset is computed using ``%Stride``'s bitwidth. This
-allows for convenient loading of sub matrixes. If ``<IsVolatile>`` is true, the
-intrinsic is considered a :ref:`volatile memory access <volatile>`. The result
-matrix is returned in the result vector. If the ``%Ptr`` argument is known to
-be aligned to some boundary, this can be specified as an attribute on the
-argument.
+different columns.  This allows for convenient loading of sub matrixes.
+Independent of ``%Stride``'s bitwidth, the offset is computed using the target
+daya layout's pointer index type. If ``<IsVolatile>`` is true, the intrinsic is
+considered a :ref:`volatile memory access <volatile>`.  The result matrix is
+returned in the result vector. If the ``%Ptr`` argument is known to be aligned
+to some boundary, this can be specified as an attribute on the argument.
 
 Arguments:
 """"""""""
@@ -21114,9 +21114,9 @@ Overview:
 
 The '``llvm.matrix.column.major.store.*``' intrinsics store the ``<Rows> x
 <Cols>`` matrix in ``%In`` to memory using a stride of ``%Stride`` between
-columns. The offset is computed using ``%Stride``'s bitwidth. If
-``<IsVolatile>`` is true, the intrinsic is considered a
-:ref:`volatile memory access <volatile>`.
+columns.  Independent of ``%Stride``'s bitwidth, the offset is computed using
+the target daya layout's pointer index type.  If ``<IsVolatile>`` is true, the
+intrinsic is considered a :ref:`volatile memory access <volatile>`.
 
 If the ``%Ptr`` argument is known to be aligned to some boundary, this can be
 specified as an attribute on the argument.

llvm/lib/Transforms/Scalar/LowerMatrixIntrinsics.cpp

@@ -1295,6 +1295,24 @@ class LowerMatrixIntrinsics {
     return commonAlignment(InitialAlign, ElementSizeInBits / 8);
   }
 
+  IntegerType *getIndexType(Value *Ptr) const {
+    return cast<IntegerType>(DL.getIndexType(Ptr->getType()));
+  }
+
+  Value *getIndex(Value *Ptr, uint64_t V) const {
+    return ConstantInt::get(getIndexType(Ptr), V);
+  }
+
+  Value *castToIndexType(Value *Ptr, Value *V, IRBuilder<> &Builder) const {
+    assert(isa<IntegerType>(V->getType()) &&
+           "Attempted to cast non-integral type to integer index");
+    // In case the data layout's index type differs in width from the type of
+    // the value we're given, truncate or zero extend to the appropriate width.
+    // We zero extend here as indices are unsigned.
+    return Builder.CreateZExtOrTrunc(V, getIndexType(Ptr),
+                                     V->getName() + ".cast");
+  }
+
   /// Load a matrix with \p Shape starting at \p Ptr and using \p Stride between
   /// vectors.
   MatrixTy loadMatrix(Type *Ty, Value *Ptr, MaybeAlign MAlign, Value *Stride,
@@ -1304,6 +1322,7 @@ class LowerMatrixIntrinsics {
     Type *VecTy = FixedVectorType::get(EltTy, Shape.getStride());
     Value *EltPtr = Ptr;
     MatrixTy Result;
+    Stride = castToIndexType(Ptr, Stride, Builder);
     for (unsigned I = 0, E = Shape.getNumVectors(); I < E; ++I) {
       Value *GEP = computeVectorAddr(
           EltPtr, Builder.getIntN(Stride->getType()->getScalarSizeInBits(), I),
@@ -1325,14 +1344,14 @@ class LowerMatrixIntrinsics {
                       ShapeInfo ResultShape, Type *EltTy,
                       IRBuilder<> &Builder) {
     Value *Offset = Builder.CreateAdd(
-        Builder.CreateMul(J, Builder.getInt64(MatrixShape.getStride())), I);
+        Builder.CreateMul(J, getIndex(MatrixPtr, MatrixShape.getStride())), I);
 
     Value *TileStart = Builder.CreateGEP(EltTy, MatrixPtr, Offset);
     auto *TileTy = FixedVectorType::get(EltTy, ResultShape.NumRows *
                                                    ResultShape.NumColumns);
 
     return loadMatrix(TileTy, TileStart, Align,
-                      Builder.getInt64(MatrixShape.getStride()), IsVolatile,
+                      getIndex(MatrixPtr, MatrixShape.getStride()), IsVolatile,
                       ResultShape, Builder);
   }
 
@@ -1363,14 +1382,15 @@ class LowerMatrixIntrinsics {
                    MaybeAlign MAlign, bool IsVolatile, ShapeInfo MatrixShape,
                    Value *I, Value *J, Type *EltTy, IRBuilder<> &Builder) {
     Value *Offset = Builder.CreateAdd(
-        Builder.CreateMul(J, Builder.getInt64(MatrixShape.getStride())), I);
+        Builder.CreateMul(J, getIndex(MatrixPtr, MatrixShape.getStride())), I);
 
     Value *TileStart = Builder.CreateGEP(EltTy, MatrixPtr, Offset);
     auto *TileTy = FixedVectorType::get(EltTy, StoreVal.getNumRows() *
                                                    StoreVal.getNumColumns());
 
     storeMatrix(TileTy, StoreVal, TileStart, MAlign,
-                Builder.getInt64(MatrixShape.getStride()), IsVolatile, Builder);
+                getIndex(MatrixPtr, MatrixShape.getStride()), IsVolatile,
+                Builder);
   }
 
   /// Store matrix \p StoreVal starting at \p Ptr and using \p Stride between
@@ -1380,6 +1400,7 @@ class LowerMatrixIntrinsics {
                        IRBuilder<> &Builder) {
     auto *VType = cast<FixedVectorType>(Ty);
     Value *EltPtr = Ptr;
+    Stride = castToIndexType(Ptr, Stride, Builder);
     for (auto Vec : enumerate(StoreVal.vectors())) {
       Value *GEP = computeVectorAddr(
           EltPtr,
@@ -2011,18 +2032,17 @@ class LowerMatrixIntrinsics {
             const unsigned TileM = std::min(M - K, unsigned(TileSize));
             MatrixTy A =
                 loadMatrix(APtr, LoadOp0->getAlign(), LoadOp0->isVolatile(),
-                           LShape, Builder.getInt64(I), Builder.getInt64(K),
+                           LShape, getIndex(APtr, I), getIndex(APtr, K),
                            {TileR, TileM}, EltType, Builder);
             MatrixTy B =
                 loadMatrix(BPtr, LoadOp1->getAlign(), LoadOp1->isVolatile(),
-                           RShape, Builder.getInt64(K), Builder.getInt64(J),
+                           RShape, getIndex(BPtr, K), getIndex(BPtr, J),
                            {TileM, TileC}, EltType, Builder);
             emitMatrixMultiply(Res, A, B, Builder, true, false,
                                getFastMathFlags(MatMul));
           }
           storeMatrix(Res, CPtr, Store->getAlign(), Store->isVolatile(), {R, M},
-                      Builder.getInt64(I), Builder.getInt64(J), EltType,
-                      Builder);
+                      getIndex(CPtr, I), getIndex(CPtr, J), EltType, Builder);
         }
     }
 
@@ -2254,15 +2274,14 @@ class LowerMatrixIntrinsics {
   /// Lower load instructions.
   MatrixTy VisitLoad(LoadInst *Inst, const ShapeInfo &SI, Value *Ptr,
                      IRBuilder<> &Builder) {
-    return LowerLoad(Inst, Ptr, Inst->getAlign(),
-                     Builder.getInt64(SI.getStride()), Inst->isVolatile(), SI,
-                     Builder);
+    return LowerLoad(Inst, Ptr, Inst->getAlign(), getIndex(Ptr, SI.getStride()),
+                     Inst->isVolatile(), SI, Builder);
   }
 
   MatrixTy VisitStore(StoreInst *Inst, const ShapeInfo &SI, Value *StoredVal,
                       Value *Ptr, IRBuilder<> &Builder) {
     return LowerStore(Inst, StoredVal, Ptr, Inst->getAlign(),
-                      Builder.getInt64(SI.getStride()), Inst->isVolatile(), SI,
+                      getIndex(Ptr, SI.getStride()), Inst->isVolatile(), SI,
                       Builder);
   }