8297715: RISC-V: C2: Use single-bit instructions from the Zbs extension

src/hotspot/cpu/riscv/assembler_riscv.hpp

@@ -1943,7 +1943,7 @@ enum Nf {
 
 // ====================================
 // RISC-V Bit-Manipulation Extension
-// Currently only support Zba and Zbb.
+// Currently only support Zba, Zbb and Zbs bitmanip extensions.
 // ====================================
 #define INSN(NAME, op, funct3, funct7)                  \
   void NAME(Register Rd, Register Rs1, Register Rs2) {  \
@@ -2018,6 +2018,7 @@ enum Nf {
 
   INSN(rori,    0b0010011, 0b101, 0b011000);
   INSN(slli_uw, 0b0011011, 0b001, 0b000010);
+  INSN(bexti,   0b0010011, 0b101, 0b010010);
 
 #undef INSN
 

src/hotspot/cpu/riscv/globals_riscv.hpp

@@ -105,6 +105,7 @@ define_pd_global(intx, InlineSmallCode,          1000);
   experimental(bool, UseRVV, false, "Use RVV instructions")                      \
   experimental(bool, UseZba, false, "Use Zba instructions")                      \
   experimental(bool, UseZbb, false, "Use Zbb instructions")                      \
+  experimental(bool, UseZbs, false, "Use Zbs instructions")                      \
   experimental(bool, UseRVC, false, "Use RVC instructions")
 
 #endif // CPU_RISCV_GLOBALS_RISCV_HPP

src/hotspot/cpu/riscv/riscv.ad

@@ -2682,6 +2682,14 @@ operand immI_16bits()
   interface(CONST_INTER);
 %}
 
+operand immIpowerOf2() %{
+  predicate(is_power_of_2((juint)(n->get_int())));
+  match(ConI);
+  op_cost(0);
+  format %{ %}
+  interface(CONST_INTER);
+%}
+
 // Long Immediate: low 32-bit mask
 operand immL_32bits()
 %{

src/hotspot/cpu/riscv/riscv_b.ad

@@ -447,5 +447,20 @@ instruct ornL_reg_reg_b(iRegLNoSp dst, iRegL src1, iRegL src2, immL_M1 m1) %{
            as_Register($src2$$reg));
   %}
 
+  ins_pipe(ialu_reg_reg);
+
+%}
+
+// AndI 0b0..010..0 + ConvI2B
+instruct convI2Bool_andI_reg_immIpowerOf2(iRegINoSp dst, iRegIorL2I src, immIpowerOf2 mask) %{
+  predicate(UseZbs);
+  match(Set dst (Conv2B (AndI src mask)));
+  ins_cost(ALU_COST);
+
+  format %{ "bexti  $dst, $src, $mask\t#@convI2Bool_andI_reg_immIpowerOf2" %}
+  ins_encode %{
+    __ bexti($dst$$Register, $src$$Register, exact_log2((juint)($mask$$constant)));
+  %}
+
   ins_pipe(ialu_reg_reg);
 %}