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Optimize access of array member in a structure. #13972

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May 12, 2023
Merged

Optimize access of array member in a structure. #13972

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21 changes: 18 additions & 3 deletions src/codegen/llvm.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -5865,19 +5865,34 @@ pub const FuncGen = struct {
const array_ty = self.air.typeOf(bin_op.lhs);
const array_llvm_val = try self.resolveInst(bin_op.lhs);
const rhs = try self.resolveInst(bin_op.rhs);
const array_llvm_ty = try self.dg.lowerType(array_ty);
const elem_ty = array_ty.childType();
if (isByRef(array_ty)) {
const array_llvm_ty = try self.dg.lowerType(array_ty);
const indices: [2]*llvm.Value = .{ self.context.intType(32).constNull(), rhs };
const elem_ptr = self.builder.buildInBoundsGEP(array_llvm_ty, array_llvm_val, &indices, indices.len, "");
const elem_ty = array_ty.childType();
if (isByRef(elem_ty)) {
const elem_ptr = self.builder.buildInBoundsGEP(array_llvm_ty, array_llvm_val, &indices, indices.len, "");
if (canElideLoad(self, body_tail))
return elem_ptr;

const target = self.dg.module.getTarget();
return self.loadByRef(elem_ptr, elem_ty, elem_ty.abiAlignment(target), false);
} else {
const lhs_index = Air.refToIndex(bin_op.lhs).?;
const elem_llvm_ty = try self.dg.lowerType(elem_ty);
if (self.air.instructions.items(.tag)[lhs_index] == .load) {
const load_data = self.air.instructions.items(.data)[lhs_index];
const load_ptr = load_data.ty_op.operand;
const load_ptr_tag = self.air.instructions.items(.tag)[Air.refToIndex(load_ptr).?];
switch (load_ptr_tag) {
.struct_field_ptr, .struct_field_ptr_index_0, .struct_field_ptr_index_1, .struct_field_ptr_index_2, .struct_field_ptr_index_3 => {
const load_ptr_inst = try self.resolveInst(load_ptr);
const gep = self.builder.buildInBoundsGEP(array_llvm_ty, load_ptr_inst, &indices, indices.len, "");
return self.builder.buildLoad(elem_llvm_ty, gep, "");
},
else => {},
}
}
const elem_ptr = self.builder.buildInBoundsGEP(array_llvm_ty, array_llvm_val, &indices, indices.len, "");
return self.builder.buildLoad(elem_llvm_ty, elem_ptr, "");
}
}
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