[Bug d/107241] New: std.bitmanip.bigEndianToNative et al not inlined

["witold.baryluk+gcc at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107241

            Bug ID: 107241
           Summary: std.bitmanip.bigEndianToNative et al not inlined
           Product: gcc
           Version: 12.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: d
          Assignee: ibuclaw at gdcproject dot org
          Reporter: witold.baryluk+gcc at gmail dot com
  Target Milestone: ---

gdc fails to inline number of small functions that should fully inline and end
in single instruction.

on amd64 / x86, for example std.bitmanip.bigEndianToNative causes a chain of
calls / jumps, even with @attribute("flatten")



import std.bitmanip;
import gcc.attributes;

@attribute("flatten")
size_t f(char[] b) {
    return std.bitmanip.bigEndianToNative!(size_t,
8)(cast(ubyte[8])(b[2..10]));
}




gcc -O3 -march=znver2 -frelease


pure nothrow @nogc @safe ulong
std.bitmanip.swapEndian!(ulong).swapEndian(const(ulong)):
        mov     rax, rdi
        bswap   rax
        ret
pure nothrow @nogc @safe ulong std.bitmanip.endianToNativeImpl!(true, ulong,
8uL).endianToNativeImpl(ubyte[8]):
        jmp     pure nothrow @nogc @safe ulong
std.bitmanip.swapEndian!(ulong).swapEndian(const(ulong))
pure nothrow @nogc @safe ulong std.bitmanip.bigEndianToNative!(ulong,
8uL).bigEndianToNative(ubyte[8]):
        jmp     pure nothrow @nogc @safe ulong
std.bitmanip.endianToNativeImpl!(true, ulong, 8uL).endianToNativeImpl(ubyte[8])
ulong example.f(char[]):
        mov     rdi, QWORD PTR [rsi+2]
        jmp     pure nothrow @nogc @safe ulong
std.bitmanip.bigEndianToNative!(ulong, 8uL).bigEndianToNative(ubyte[8])




No issues with LDC.

ulong example.f(char[]):
        mov     rax, qword ptr [rsi + 2]
        bswap   rax
        ret



godbolt: https://godbolt.org/z/Pj3f7oGso