[llvm-bugs] [Bug 26083] New: [Combine] !((A > 0) && (B > 0)) -> (A <= 0 || B <= 0) missed when A has multiple users

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=26083

            Bug ID: 26083
           Summary: [Combine] !((A > 0) && (B > 0)) -> (A <= 0 || B <= 0)
                    missed when A has multiple users
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Windows NT
            Status: NEW
          Severity: normal
          Priority: P
         Component: Scalar Optimizations
          Assignee: unassignedbugs at nondot.org
          Reporter: mcrosier at codeaurora.org
                CC: bmakam at codeaurora.org, llvm-bugs at lists.llvm.org
    Classification: Unclassified

Test case:
void foo(int A, int B);

void test(int A, int B, int C) {
 foo(!(A > 0 && B > 0),
     !(A > 0 && C > 0));
}

When targeting AArch64 at -O3 I get the following assembly:

test1:                                  // @test1
        cmp     w0, #0          // =0
        cset    w8, gt
        cmp     w1, #0          // =0
        cset    w9, gt
        cmp     w2, #0          // =0
        cset    w10, gt
        and     w9, w8, w9
        and     w8, w8, w10
        eor     w0, w9, #0x1
        eor     w1, w8, #0x1
        b       foo

However, we should be able to generate something like this assembly:
        cmp      w0, #1          // =1
        cset     w8, lt
        cmp      w1, #1          // =1
        cset     w9, lt
        cmp      w2, #1          // =1
        orr      w0, w8, w9
        cset     w9, lt
        orr      w1, w8, w9
        b       foo

which would replace 2 ANDs and 2 EORs with 2 ORs.  My example is for AArch64,
but I can't imagine this is a target-specific combine.

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