[llvm-bugs] [Bug 44378] New: Unrecognized variant of memcpy-like loop by LoopIdiomRecognize

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=44378

            Bug ID: 44378
           Summary: Unrecognized variant of memcpy-like loop by
                    LoopIdiomRecognize
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Loop Optimizer
          Assignee: unassignedbugs at nondot.org
          Reporter: david.bolvansky at gmail.com
                CC: llvm-bugs at lists.llvm.org

void f(unsigned char*__restrict p,unsigned char*__restrict q,int n){
  for(int i=0;i<n;++i)
    *p++=*q++;
}

Clang produces huge amount of assembly code, while GCC 10 produces:

f(unsigned char*, unsigned char*, int):
        test    edx, edx
        jle     .L1
        movsx   rdx, edx
        jmp     memcpy
.L1:
        ret

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