[llvm] [RISCV][ISel] Select `binvi` for pattern `icmp eq/ne X, pow2` (PR #110957)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-risc-v

Author: Yingwei Zheng (dtcxzyw)

<details>
<summary>Changes</summary>

This patch selects `binvi` for pattern `icmp eq/ne X, pow2` when zbs is available.


---
Full diff: https://github.com/llvm/llvm-project/pull/110957.diff


3 Files Affected:

- (modified) llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp (+8) 
- (modified) llvm/test/CodeGen/RISCV/rv32zbs.ll (+46) 
- (modified) llvm/test/CodeGen/RISCV/rv64zbs.ll (+64) 


``````````diff
diff --git a/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp b/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
index 3e3f3c2eca1468..dc3f8254cb4e00 100644
--- a/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
@@ -2938,6 +2938,14 @@ bool RISCVDAGToDAGISel::selectSETCC(SDValue N, ISD::CondCode ExpectedCCVal,
                     0);
       return true;
     }
+    if (isPowerOf2_64(CVal) && Subtarget->hasStdExtZbs()) {
+      Val = SDValue(
+          CurDAG->getMachineNode(
+              RISCV::BINVI, DL, N->getValueType(0), LHS,
+              CurDAG->getTargetConstant(Log2_64(CVal), DL, N->getValueType(0))),
+          0);
+      return true;
+    }
   }
 
   // If nothing else we can XOR the LHS and RHS to produce zero if they are
diff --git a/llvm/test/CodeGen/RISCV/rv32zbs.ll b/llvm/test/CodeGen/RISCV/rv32zbs.ll
index 30aba61ba47469..c0b9e0b3c7748e 100644
--- a/llvm/test/CodeGen/RISCV/rv32zbs.ll
+++ b/llvm/test/CodeGen/RISCV/rv32zbs.ll
@@ -837,3 +837,49 @@ define i64 @bset_trailing_ones_i64_no_mask(i64 %a) nounwind {
   %not = xor i64 %shift, -1
   ret i64 %not
 }
+
+define i1 @icmp_eq_pow2(i32 %x) nounwind {
+; RV32I-LABEL: icmp_eq_pow2:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    lui a1, 8
+; RV32I-NEXT:    xor a0, a0, a1
+; RV32I-NEXT:    seqz a0, a0
+; RV32I-NEXT:    ret
+;
+; RV32ZBS-LABEL: icmp_eq_pow2:
+; RV32ZBS:       # %bb.0:
+; RV32ZBS-NEXT:    binvi a0, a0, 15
+; RV32ZBS-NEXT:    seqz a0, a0
+; RV32ZBS-NEXT:    ret
+  %cmp = icmp eq i32 %x, 32768
+  ret i1 %cmp
+}
+
+define i1 @icmp_ne_pow2(i32 %x) nounwind {
+; RV32I-LABEL: icmp_ne_pow2:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    lui a1, 8
+; RV32I-NEXT:    xor a0, a0, a1
+; RV32I-NEXT:    seqz a0, a0
+; RV32I-NEXT:    ret
+;
+; RV32ZBS-LABEL: icmp_ne_pow2:
+; RV32ZBS:       # %bb.0:
+; RV32ZBS-NEXT:    binvi a0, a0, 15
+; RV32ZBS-NEXT:    seqz a0, a0
+; RV32ZBS-NEXT:    ret
+  %cmp = icmp eq i32 %x, 32768
+  ret i1 %cmp
+}
+
+define i1 @icmp_eq_nonpow2(i32 %x) nounwind {
+; CHECK-LABEL: icmp_eq_nonpow2:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    lui a1, 8
+; CHECK-NEXT:    addi a1, a1, -1
+; CHECK-NEXT:    xor a0, a0, a1
+; CHECK-NEXT:    seqz a0, a0
+; CHECK-NEXT:    ret
+  %cmp = icmp eq i32 %x, 32767
+  ret i1 %cmp
+}
diff --git a/llvm/test/CodeGen/RISCV/rv64zbs.ll b/llvm/test/CodeGen/RISCV/rv64zbs.ll
index d370b1877470c4..577005a051b204 100644
--- a/llvm/test/CodeGen/RISCV/rv64zbs.ll
+++ b/llvm/test/CodeGen/RISCV/rv64zbs.ll
@@ -1146,3 +1146,67 @@ define signext i64 @bset_trailing_ones_i64_no_mask(i64 signext %a) nounwind {
   %not = xor i64 %shift, -1
   ret i64 %not
 }
+
+define i1 @icmp_eq_pow2(i32 signext %x) nounwind {
+; RV64I-LABEL: icmp_eq_pow2:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    lui a1, 8
+; RV64I-NEXT:    xor a0, a0, a1
+; RV64I-NEXT:    seqz a0, a0
+; RV64I-NEXT:    ret
+;
+; RV64ZBS-LABEL: icmp_eq_pow2:
+; RV64ZBS:       # %bb.0:
+; RV64ZBS-NEXT:    binvi a0, a0, 15
+; RV64ZBS-NEXT:    seqz a0, a0
+; RV64ZBS-NEXT:    ret
+  %cmp = icmp eq i32 %x, 32768
+  ret i1 %cmp
+}
+
+define i1 @icmp_eq_pow2_64(i64 %x) nounwind {
+; RV64I-LABEL: icmp_eq_pow2_64:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    li a1, 1
+; RV64I-NEXT:    slli a1, a1, 40
+; RV64I-NEXT:    xor a0, a0, a1
+; RV64I-NEXT:    seqz a0, a0
+; RV64I-NEXT:    ret
+;
+; RV64ZBS-LABEL: icmp_eq_pow2_64:
+; RV64ZBS:       # %bb.0:
+; RV64ZBS-NEXT:    binvi a0, a0, 40
+; RV64ZBS-NEXT:    seqz a0, a0
+; RV64ZBS-NEXT:    ret
+  %cmp = icmp eq i64 %x, 1099511627776
+  ret i1 %cmp
+}
+
+define i1 @icmp_ne_pow2(i32 signext %x) nounwind {
+; RV64I-LABEL: icmp_ne_pow2:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    lui a1, 8
+; RV64I-NEXT:    xor a0, a0, a1
+; RV64I-NEXT:    seqz a0, a0
+; RV64I-NEXT:    ret
+;
+; RV64ZBS-LABEL: icmp_ne_pow2:
+; RV64ZBS:       # %bb.0:
+; RV64ZBS-NEXT:    binvi a0, a0, 15
+; RV64ZBS-NEXT:    seqz a0, a0
+; RV64ZBS-NEXT:    ret
+  %cmp = icmp eq i32 %x, 32768
+  ret i1 %cmp
+}
+
+define i1 @icmp_eq_nonpow2(i32 signext %x) nounwind {
+; CHECK-LABEL: icmp_eq_nonpow2:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    lui a1, 8
+; CHECK-NEXT:    addiw a1, a1, -1
+; CHECK-NEXT:    xor a0, a0, a1
+; CHECK-NEXT:    seqz a0, a0
+; CHECK-NEXT:    ret
+  %cmp = icmp eq i32 %x, 32767
+  ret i1 %cmp
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/110957