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Merged
merged 1 commit into from
Aug 22, 2025
Merged

Recursive template instantations #677

merged 1 commit into from
Aug 22, 2025

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robertoraggi
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very WIP.. enough for

extern "C" int printf(const char*, ...);

template <int N>
struct Sum {
  enum Value { value = Sum<N - 1>::value + N };
};

template <>
struct Sum<0> {
  enum Value { value = 0 };
};

auto main() -> int {
  enum { N = 1024 };
  static_assert(Sum<N>::value == (N * (N + 1)) / 2);
  printf("Sum<%d>::value = %d\n", N, Sum<N>::value);
  return 0;
}

cxx x.cc -fcheck -dump-symbols | head -20

namespace
  function int printf(const char*...)
  template class Sum<int>
    parameter object<0, 0, int> N
    enum Value : int
      enumerator Value value
    using Value value
    [specializations]
      class Sum<0>
        enum Value : int
          enumerator Value value = 0
        using Value value
      class Sum<1024>
        enum Value : int
          enumerator Value value = 524800
        using Value value
      class Sum<1023>
        enum Value : int
          enumerator Value value = 523776
        using Value value

cxx x.cc -fcheck -toolchain macos -emit-ir -o -

cxx x.cc -fcheck -toolchain macos -emit-ir -o -
module @x.cc attributes {"cxx.data-layout" = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-n32:64-S128-Fn32", cxx.triple = "arm64-apple-macosx15.0.0", dlti.dl_spec = #dlti.dl_spec<!llvm.ptr<270> = dense<32> : vector<4xi64>, !llvm.ptr<271> = dense<32> : vector<4xi64>, !llvm.ptr<272> = dense<64> : vector<4xi64>, i64 = dense<64> : vector<2xi64>, i128 = dense<128> : vector<2xi64>, !llvm.ptr = dense<64> : vector<4xi64>, i1 = dense<8> : vector<2xi64>, i8 = dense<8> : vector<2xi64>, i16 = dense<16> : vector<2xi64>, i32 = dense<32> : vector<2xi64>, f16 = dense<16> : vector<2xi64>, f64 = dense<64> : vector<2xi64>, f128 = dense<128> : vector<2xi64>, "dlti.endianness" = "little", "dlti.mangling_mode" = "o", "dlti.legal_int_widths" = array<i32: 32, 64>, "dlti.stack_alignment" = 128 : i64, "dlti.function_pointer_alignment" = #dlti.function_pointer_alignment<32, function_dependent = true>>, llvm.data_layout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-n32:64-S128-Fn32", llvm.target_triple = "arm64-apple-macosx15.0.0"} {
  llvm.func @printf(!llvm.ptr, ...) -> i32
  llvm.func @main() -> i32 {
    %0 = llvm.mlir.constant(0 : i32) : i32
    %1 = llvm.mlir.constant(524800 : i32) : i32
    %2 = llvm.mlir.constant(1024 : i32) : i32
    %3 = llvm.mlir.addressof @".str1" : !llvm.ptr
    %4 = llvm.mlir.constant(1 : index) : i64
    %5 = llvm.alloca %4 x i32 : (i64) -> !llvm.ptr
    %6 = llvm.call @printf(%3, %2, %1) vararg(!llvm.func<i32 (ptr, ...)>) : (!llvm.ptr, i32, i32) -> i32
    llvm.store %0, %5 : i32, !llvm.ptr
    llvm.br ^bb1
  ^bb1:  // pred: ^bb0
    %7 = llvm.load %5 : !llvm.ptr -> i32
    llvm.return %7 : i32
  }
  llvm.mlir.global private constant @".str1"("Sum<%d>::value = %d\0A\00") {addr_space = 0 : i32}
}
cxx x.cc -fcheck -toolchain macos -emit-llvm -o - | lli

Sum<1024>::value = 524800

@robertoraggi robertoraggi force-pushed the fiscal-hare branch 2 times, most recently from a74a773 to cb0e0ce Compare August 22, 2025 18:35
@robertoraggi robertoraggi merged commit cf9426d into main Aug 22, 2025
10 of 18 checks passed
@robertoraggi robertoraggi deleted the fiscal-hare branch August 22, 2025 19:07
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