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This patch adds infrastructure for forward shape propagation to LowerMatrixIntrinsics. It also updates the pass to make use of the shape information to break up larger vector operations and to eliminate unnecessary conversion operations between columnwise matrixes and flattened vectors: if shape information is available for an instruction, lower the operation to a set of instructions operating on columns. For example, a store of a matrix is broken down into separate stores for each column. For users that do not have shape information (e.g. because they do not yet support shape information aware lowering), we pack the result columns into a flat vector and update those users. It also adds shape aware lowering for the first non-intrinsic instruction: vector stores. Example: For %c = call <4 x double> @llvm.matrix.transpose(<4 x double> %a, i32 2, i32 2) store <4 x double> %c, <4 x double>* %Ptr We generate the code below without shape propagation. Note %9 which combines the columns of the transposed matrix into a flat vector. %split = shufflevector <4 x double> %a, <4 x double> undef, <2 x i32> <i32 0, i32 1> %split1 = shufflevector <4 x double> %a, <4 x double> undef, <2 x i32> <i32 2, i32 3> %1 = extractelement <2 x double> %split, i64 0 %2 = insertelement <2 x double> undef, double %1, i64 0 %3 = extractelement <2 x double> %split1, i64 0 %4 = insertelement <2 x double> %2, double %3, i64 1 %5 = extractelement <2 x double> %split, i64 1 %6 = insertelement <2 x double> undef, double %5, i64 0 %7 = extractelement <2 x double> %split1, i64 1 %8 = insertelement <2 x double> %6, double %7, i64 1 %9 = shufflevector <2 x double> %4, <2 x double> %8, <4 x i32> <i32 0, i32 1, i32 2, i32 3> store <4 x double> %9, <4 x double>* %Ptr With this patch, we propagate the 2x2 shape information from the transpose to the store and we generate the code below. Note that we store the columns directly and do not need an extra shuffle. %9 = bitcast <4 x double>* %Ptr to double* %10 = bitcast double* %9 to <2 x double>* store <2 x double> %4, <2 x double>* %10, align 8 %11 = getelementptr double, double* %9, i32 2 %12 = bitcast double* %11 to <2 x double>* store <2 x double> %8, <2 x double>* %12, align 8 Reviewers: anemet, Gerolf, reames, hfinkel, andrew.w.kaylor Reviewed By: anemet Differential Revision: https://reviews.llvm.org/D70897
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