[PATCH] D131482: [RISCV] Return true in hasBitTest when Zbs is enabled and update BEXTI pattern for resulting canonicalisation

[Alex Bradbury via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rG547160848c42: [RISCV] Return true in hasBitTest when Zbs is enabled and update BEXTI pattern… (authored by asb).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D131482/new/

https://reviews.llvm.org/D131482

Files:
  llvm/lib/Target/RISCV/RISCVISelLowering.cpp
  llvm/lib/Target/RISCV/RISCVInstrInfoZb.td
  llvm/test/CodeGen/RISCV/bittest.ll


Index: llvm/test/CodeGen/RISCV/bittest.ll
===================================================================
--- llvm/test/CodeGen/RISCV/bittest.ll
+++ llvm/test/CodeGen/RISCV/bittest.ll
@@ -156,11 +156,17 @@
 ; RV32-NEXT:    li a1, 0
 ; RV32-NEXT:    ret
 ;
-; RV64-LABEL: bittest_31_i64:
-; RV64:       # %bb.0:
-; RV64-NEXT:    not a0, a0
-; RV64-NEXT:    srliw a0, a0, 31
-; RV64-NEXT:    ret
+; RV64I-LABEL: bittest_31_i64:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    not a0, a0
+; RV64I-NEXT:    srliw a0, a0, 31
+; RV64I-NEXT:    ret
+;
+; RV64ZBS-LABEL: bittest_31_i64:
+; RV64ZBS:       # %bb.0:
+; RV64ZBS-NEXT:    not a0, a0
+; RV64ZBS-NEXT:    bexti a0, a0, 31
+; RV64ZBS-NEXT:    ret
   %shr = lshr i64 %a, 31
   %not = xor i64 %shr, -1
   %and = and i64 %not, 1
Index: llvm/lib/Target/RISCV/RISCVInstrInfoZb.td
===================================================================
--- llvm/lib/Target/RISCV/RISCVInstrInfoZb.td
+++ llvm/lib/Target/RISCV/RISCVInstrInfoZb.td
@@ -89,7 +89,7 @@
                                    SDLoc(N), N->getValueType(0));
 }]>;
 
-def BSETINVXForm : SDNodeXForm<imm, [{
+def SingleBitSetMaskToIndex : SDNodeXForm<imm, [{
   // Find the lowest 1.
   return CurDAG->getTargetConstant(countTrailingZeros(N->getZExtValue()),
                                    SDLoc(N), N->getValueType(0));
@@ -103,11 +103,11 @@
 }], BCLRXForm>;
 
 // Checks if this mask has a single 1 bit and cannot be used with ORI/XORI.
-def BSETINVMask : ImmLeaf<XLenVT, [{
+def SingleBitSetMask : ImmLeaf<XLenVT, [{
   if (Subtarget->is64Bit())
     return !isInt<12>(Imm) && isPowerOf2_64(Imm);
   return !isInt<12>(Imm) && isPowerOf2_32(Imm);
-}], BSETINVXForm>;
+}], SingleBitSetMaskToIndex>;
 
 // Check if (or r, i) can be optimized to (BSETI (BSETI r, i0), i1),
 // in which i = (1 << i0) | (1 << i1).
@@ -885,16 +885,16 @@
 
 def : Pat<(and GPR:$rs1, BCLRMask:$mask),
           (BCLRI GPR:$rs1, BCLRMask:$mask)>;
-def : Pat<(or GPR:$rs1, BSETINVMask:$mask),
-          (BSETI GPR:$rs1, BSETINVMask:$mask)>;
-def : Pat<(xor GPR:$rs1, BSETINVMask:$mask),
-          (BINVI GPR:$rs1, BSETINVMask:$mask)>;
+def : Pat<(or GPR:$rs1, SingleBitSetMask:$mask),
+          (BSETI GPR:$rs1, SingleBitSetMask:$mask)>;
+def : Pat<(xor GPR:$rs1, SingleBitSetMask:$mask),
+          (BINVI GPR:$rs1, SingleBitSetMask:$mask)>;
 
 def : Pat<(and (srl GPR:$rs1, uimmlog2xlen:$shamt), (XLenVT 1)),
           (BEXTI GPR:$rs1, uimmlog2xlen:$shamt)>;
 
-def : Pat<(and (not (srl GPR:$rs1, uimmlog2xlen:$shamt)), (XLenVT 1)),
-          (XORI (BEXTI GPR:$rs1, uimmlog2xlen:$shamt), (XLenVT 1))>;
+def : Pat<(seteq (and GPR:$rs1, SingleBitSetMask:$mask), 0),
+          (BEXTI (XORI GPR:$rs1, -1), SingleBitSetMask:$mask)>;
 
 def : Pat<(or GPR:$r, BSETINVTwoBitsMask:$i),
           (BSETI (BSETI GPR:$r, (TrailingZerosXForm BSETINVTwoBitsMask:$i)),
Index: llvm/lib/Target/RISCV/RISCVISelLowering.cpp
===================================================================
--- llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -1178,6 +1178,9 @@
 }
 
 bool RISCVTargetLowering::hasBitTest(SDValue X, SDValue Y) const {
+  // Zbs provides BEXT[_I], which can be used with SEQZ/SNEZ as a bit test.
+  if (Subtarget.hasStdExtZbs())
+    return X.getValueType().isScalarInteger();
   // We can use ANDI+SEQZ/SNEZ as a bit test. Y contains the bit position.
   auto *C = dyn_cast<ConstantSDNode>(Y);
   return C && C->getAPIntValue().ule(10);


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