[llvm] [PowerPC] fold i128 equality/inequality compares of two loads into a vectorized compare using vcmpequb.p when Altivec is available (PR #158657)

[zhijian lin via llvm-commits]

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@@ -122,23 +117,17 @@ define signext i32 @equalityFoldOneConstant(ptr %X) {
 ; CHECK-LABEL: equalityFoldOneConstant:
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    li 5, 1
-; CHECK-NEXT:    ld 4, 0(3)
+; CHECK-NEXT:    ld 4, 8(3)
+; CHECK-NEXT:    ld 3, 0(3)
 ; CHECK-NEXT:    rldic 5, 5, 32, 31
-; CHECK-NEXT:    cmpld 4, 5
-; CHECK-NEXT:    bne 0, .LBB6_2
-; CHECK-NEXT:  # %bb.1: # %loadbb1
+; CHECK-NEXT:    xor 3, 3, 5
 ; CHECK-NEXT:    lis 5, -32768
-; CHECK-NEXT:    ld 4, 8(3)
-; CHECK-NEXT:    li 3, 0
 ; CHECK-NEXT:    ori 5, 5, 1
 ; CHECK-NEXT:    rldic 5, 5, 1, 30
-; CHECK-NEXT:    cmpld 4, 5
-; CHECK-NEXT:    beq 0, .LBB6_3
-; CHECK-NEXT:  .LBB6_2: # %res_block
-; CHECK-NEXT:    li 3, 1
-; CHECK-NEXT:  .LBB6_3: # %endblock
-; CHECK-NEXT:    cntlzw 3, 3
-; CHECK-NEXT:    srwi 3, 3, 5
+; CHECK-NEXT:    xor 4, 4, 5
+; CHECK-NEXT:    or 3, 3, 4
+; CHECK-NEXT:    cntlzd 3, 3
+; CHECK-NEXT:    rldicl 3, 3, 58, 63
----------------
diggerlin wrote:

since we change the 

[llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp](https://github.com/llvm/llvm-project/pull/158657/files/24bb9f4d13050cd0d8e4db7df240ce55ce4a611b#diff-c3b49360a8dbbb7be8915248bbbf464ff24c7a4bfd01eaaba0c739242d25ece9)

the with 16 bytes support, it change the IR which generated  by MergeICmpsLegacyPass to 

```
        t5: i128,ch = load<(load (s128) from %ir.X, align 1)> t0, t2, undef:i64
      t8: i1 = setcc Constant:i128<237684487579686500932345921536>, t5, setne:ch
```

I think we can have another to optimize patch further and make the asm as load vector from memory and compared 2 two vector.





https://github.com/llvm/llvm-project/pull/158657