[llvm-bugs] [Bug 47430] New: Missing fold &a[i] - &a[j] => i - j

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=47430

            Bug ID: 47430
           Summary: Missing fold &a[i] - &a[j] => i - j
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Scalar Optimizations
          Assignee: unassignedbugs at nondot.org
          Reporter: david.bolvansky at gmail.com
                CC: llvm-bugs at lists.llvm.org

typedef __SIZE_TYPE__ size_t;
size_t a[64];
size_t f(size_t b, size_t c)
{
  return &a[b] - &a[c];
}

Clang:
f(unsigned long, unsigned long): # @f(unsigned long, unsigned long)
  sub rdi, rsi
  lea rax, [8*rdi]
  sar rax, 3
  ret
a:
  .zero 512

GCC:
f(unsigned long, unsigned long):
        mov     rax, rdi
        sub     rax, rsi
        ret
a:
        .zero   512

https://godbolt.org/z/7M8o5a

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