[llvm-bugs] [Bug 42461] New: constexpr can't handle vector types

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=42461

            Bug ID: 42461
           Summary: constexpr can't handle vector types
           Product: clang
           Version: unspecified
          Hardware: PC
                OS: Windows NT
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Frontend
          Assignee: unassignedclangbugs at nondot.org
          Reporter: llvm-dev at redking.me.uk
                CC: llvm-bugs at lists.llvm.org, neeilans at live.com,
                    richard-llvm at metafoo.co.uk
            Blocks: 31446

Godbolt: https://godbolt.org/z/l-RaB7

We are unable to use __vector_size or ext_vector_type defined types in
constexpr functions.


typedef int __v4si __attribute__((__vector_size__(16)));

constexpr int sum_i32(__v4si x) {
  return x[0] + x[1] + x[2] + x[3];
}

constexpr __v4si add_i32(__v4si x, __v4si y) {
  return x + y;
}

clang -g0 -O3 

<source>:3:18: error: constexpr function never produces a constant expression
[-Winvalid-constexpr]

constexpr __v4si add_i32(__v4si x, __v4si y) {
                 ^

<source>:4:12: note: subexpression not valid in a constant expression
  return x + y;

           ^

<source>:7:15: error: constexpr function never produces a constant expression
[-Winvalid-constexpr]

constexpr int sum_i32(__v4si x) {

              ^

<source>:8:10: note: subexpression not valid in a constant expression
  return x[0] + x[1] + x[2] + x[3];


Referenced Bugs:

https://bugs.llvm.org/show_bug.cgi?id=31446
[Bug 31446] [feature-request] make vector intrinsics constexpr
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