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[rtl] Remove unused set-less-or-equal-than ALU ops

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These operations (ALU_SLET, ALU_SLETU) are remnants of of the original
OpenRISC design. RISC-V just has set-less-than (ALU_SLT, ALU_SLTU).

This resolves lowRISC/ibex#432 reported by @udinator.
This commit is contained in:
Pirmin Vogel 2019-10-31 10:44:40 +00:00
parent e2ab24b9e3
commit 275c3310fa
3 changed files with 9 additions and 15 deletions
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2
lint/verilator_waiver.vlt
View file

@ -28,7 +28,7 @@ lint_off -msg UNUSED -file "*/rtl/ibex_if_stage.sv" -lines 80
// Bits of signal are not used: shift_right_result_ext[32]
// cleaner to write all bits even if not all are used
lint_off -msg UNUSED -file "*/rtl/ibex_alu.sv" -lines 105
lint_off -msg UNUSED -file "*/rtl/ibex_alu.sv" -lines 104
// Bits of signal are not used: alu_adder_ext_i[0]
// Bottom bit is round, not needed

18
rtl/ibex_alu.sv
View file

@ -52,8 +52,7 @@ module ibex_alu (
ALU_EQ, ALU_NE,
ALU_GE, ALU_GEU,
ALU_LT, ALU_LTU,
ALU_SLT, ALU_SLTU,
ALU_SLET, ALU_SLETU: adder_op_b_negate = 1'b1;
ALU_SLT, ALU_SLTU: adder_op_b_negate = 1'b1;
default:;
endcase
@ -128,8 +127,7 @@ module ibex_alu (
unique case (operator_i)
ALU_GE,
ALU_LT,
ALU_SLT,
ALU_SLET: begin
ALU_SLT: begin
cmp_signed = 1'b1;
end
@ -168,12 +166,11 @@ module ibex_alu (
cmp_result = is_equal;
unique case (operator_i)
ALU_EQ: cmp_result = is_equal;
ALU_NE: cmp_result = ~is_equal;
ALU_GE, ALU_GEU: cmp_result = is_greater_equal;
ALU_EQ: cmp_result = is_equal;
ALU_NE: cmp_result = ~is_equal;
ALU_GE, ALU_GEU: cmp_result = is_greater_equal;
ALU_LT, ALU_LTU,
ALU_SLT, ALU_SLTU: cmp_result = ~is_greater_equal;
ALU_SLET, ALU_SLETU: cmp_result = ~is_greater_equal | is_equal;
ALU_SLT, ALU_SLTU: cmp_result = ~is_greater_equal;
default:;
endcase
@ -205,8 +202,7 @@ module ibex_alu (
ALU_EQ, ALU_NE,
ALU_GE, ALU_GEU,
ALU_LT, ALU_LTU,
ALU_SLT, ALU_SLTU,
ALU_SLET, ALU_SLETU: result_o = {31'h0,cmp_result};
ALU_SLT, ALU_SLTU: result_o = {31'h0,cmp_result};
default:;
endcase

4
rtl/ibex_pkg.sv
View file

@ -57,9 +57,7 @@ typedef enum logic [4:0] {
// Set lower than
ALU_SLT,
ALU_SLTU,
ALU_SLET,
ALU_SLETU
ALU_SLTU
} alu_op_e;
typedef enum logic [1:0] {