[PATCH] D156081: [RISCV] Add CZERO_EQZ/CZERO_NEZ to computeKnownBitsForTargetNode.

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
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Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D156081

Files:
  llvm/lib/Target/RISCV/RISCVISelLowering.cpp
  llvm/test/CodeGen/RISCV/xaluo.ll


Index: llvm/test/CodeGen/RISCV/xaluo.ll
===================================================================
--- llvm/test/CodeGen/RISCV/xaluo.ll
+++ llvm/test/CodeGen/RISCV/xaluo.ll
@@ -4395,8 +4395,7 @@
 ; 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 @@
 ; 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 @@
 ; 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
Index: llvm/lib/Target/RISCV/RISCVISelLowering.cpp
===================================================================
--- llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -13716,6 +13716,13 @@
     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);


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