[RISCV] Add CZERO_EQZ/CZERO_NEZ to computeKnownBitsForTargetNode.

Reviewed By: wangpc

Differential Revision: https://reviews.llvm.org/D156081

diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index 3b5e099..898f65b 100644 (file)
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -13716,6 +13716,13 @@ void RISCVTargetLowering::computeKnownBitsForTargetNode(const SDValue Op,
     Known = Known.intersectWith(Known2);
     break;
   }
+  case RISCVISD::CZERO_EQZ:
+  case RISCVISD::CZERO_NEZ:
+    Known = DAG.computeKnownBits(Op.getOperand(0), Depth + 1);
+    // Result is either all zero or operand 0. We can propagate zeros, but not
+    // ones.
+    Known.One.clearAllBits();
+    break;
   case RISCVISD::REMUW: {
     KnownBits Known2;
     Known = DAG.computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);

diff --git a/llvm/test/CodeGen/RISCV/xaluo.ll b/llvm/test/CodeGen/RISCV/xaluo.ll
index fd1e7c9..5d47ea4 100644 (file)
--- a/llvm/test/CodeGen/RISCV/xaluo.ll
+++ b/llvm/test/CodeGen/RISCV/xaluo.ll
@@ -4395,8 +4395,7 @@ define zeroext i1 @uaddo.br.i64(i64 %v1, i64 %v2) {
 ; RV32ZICOND-NEXT:    czero.eqz a1, a1, a2
 ; RV32ZICOND-NEXT:    czero.nez a0, a0, a2
 ; RV32ZICOND-NEXT:    or a0, a1, a0
-; RV32ZICOND-NEXT:    li a1, 1
-; RV32ZICOND-NEXT:    bne a0, a1, .LBB55_2
+; RV32ZICOND-NEXT:    beqz a0, .LBB55_2
 ; RV32ZICOND-NEXT:  # %bb.1: # %overflow
 ; RV32ZICOND-NEXT:    li a0, 0
 ; RV32ZICOND-NEXT:    ret
@@ -4769,8 +4768,7 @@ define zeroext i1 @usubo.br.i64(i64 %v1, i64 %v2) {
 ; RV32ZICOND-NEXT:    sltu a0, a0, a2
 ; RV32ZICOND-NEXT:    czero.nez a0, a0, a4
 ; RV32ZICOND-NEXT:    or a0, a1, a0
-; RV32ZICOND-NEXT:    li a1, 1
-; RV32ZICOND-NEXT:    bne a0, a1, .LBB59_2
+; RV32ZICOND-NEXT:    beqz a0, .LBB59_2
 ; RV32ZICOND-NEXT:  # %bb.1: # %overflow
 ; RV32ZICOND-NEXT:    li a0, 0
 ; RV32ZICOND-NEXT:    ret
@@ -5602,8 +5600,7 @@ define zeroext i1 @umulo2.br.i64(i64 %v1) {
 ; RV32ZICOND-NEXT:    sltu a1, a2, a1
 ; RV32ZICOND-NEXT:    czero.eqz a1, a1, a3
 ; RV32ZICOND-NEXT:    or a0, a1, a0
-; RV32ZICOND-NEXT:    li a1, 1
-; RV32ZICOND-NEXT:    bne a0, a1, .LBB65_2
+; RV32ZICOND-NEXT:    beqz a0, .LBB65_2
 ; RV32ZICOND-NEXT:  # %bb.1: # %overflow
 ; RV32ZICOND-NEXT:    li a0, 0
 ; RV32ZICOND-NEXT:    ret