[llvm] [SDag][ARM][RISCV] Allow lowering CTPOP into a libcall (PR #99752)

[Craig Topper via llvm-commits]

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@@ -24,31 +24,14 @@ define signext i32 @ctlz_i32(i32 signext %a) nounwind {
 ; RV64I-NEXT:    srliw a1, a0, 16
 ; RV64I-NEXT:    or a0, a0, a1
 ; RV64I-NEXT:    not a0, a0
-; RV64I-NEXT:    srliw a1, a0, 1
-; RV64I-NEXT:    lui a2, 349525
-; RV64I-NEXT:    addi a2, a2, 1365
-; RV64I-NEXT:    and a1, a1, a2
-; RV64I-NEXT:    subw a0, a0, a1
-; RV64I-NEXT:    lui a1, 209715
-; RV64I-NEXT:    addi a1, a1, 819
-; RV64I-NEXT:    and a2, a0, a1
-; RV64I-NEXT:    srliw a0, a0, 2
-; RV64I-NEXT:    and a0, a0, a1
-; RV64I-NEXT:    add a0, a2, a0
-; RV64I-NEXT:    srliw a1, a0, 4
-; RV64I-NEXT:    addw a0, a0, a1
-; RV64I-NEXT:    lui a1, 61681
-; RV64I-NEXT:    addiw a1, a1, -241
-; RV64I-NEXT:    and a0, a0, a1
-; RV64I-NEXT:    lui a1, 4112
-; RV64I-NEXT:    addiw a1, a1, 257
-; RV64I-NEXT:    call __muldi3
-; RV64I-NEXT:    srliw a0, a0, 24
+; RV64I-NEXT:    call __popcountsi2
 ; RV64I-NEXT:    ld ra, 8(sp) # 8-byte Folded Reload
 ; RV64I-NEXT:    addi sp, sp, 16
+; RV64I-NEXT:    sext.w a0, a0
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topperc wrote:

__popcountsi2 should be returning a sign extended result right?

https://github.com/llvm/llvm-project/pull/99752