[llvm-bugs] [Bug 48544] New: Bounds check not eliminated

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=48544

            Bug ID: 48544
           Summary: Bounds check not eliminated
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Scalar Optimizations
          Assignee: unassignedbugs at nondot.org
          Reporter: jmuizelaar at mozilla.com
                CC: llvm-bugs at lists.llvm.org

#include <stdlib.h>
char foo(char* data, size_t len, size_t i, size_t j) {
    if (i < len && j <= i) {
        if (j < len) {
            return data[j];
        } else {
            exit(1);
        }
    } else {
        return 0;
    }
}


compiles to:

foo(char*, unsigned long, unsigned long, unsigned long):
        cmp     rdx, rsi
        jnb     .L4
        cmp     rdx, rcx
        jb      .L4
        cmp     rsi, rcx
        jbe     .L3
        movzx   eax, BYTE PTR [rdi+rcx]
        ret
.L4:
        xor     eax, eax
        ret
.L3:
        push    rax
        mov     edi, 1
        call    exit

The call to exit should be eliminated.

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