From ebea314a6edd238cfff2563f647eeafbd57383e7 Mon Sep 17 00:00:00 2001 From: David Harris Date: Thu, 18 Jul 2024 21:38:17 -0700 Subject: [PATCH] Modified decompressor to look for illegal x0 values and hints --- src/ifu/decompress.sv | 33 +++++++++++++++++++++------------ 1 file changed, 21 insertions(+), 12 deletions(-) diff --git a/src/ifu/decompress.sv b/src/ifu/decompress.sv index 340c5055a..10d59f7f2 100644 --- a/src/ifu/decompress.sv +++ b/src/ifu/decompress.sv @@ -109,22 +109,27 @@ module decompress import cvw::*; #(parameter cvw_t P) ( LInstrD = {1'b0, immCS[11:5], rs2p, rs1p, 3'b010, immCS[4:0], 7'b0100111}; // c.fsw end else LInstrD = {1'b0, immCSD[11:5], rs2p, rs1p, 3'b011, immCSD[4:0], 7'b0100011}; //c.sd - 5'b01000: if (rds1 != 5'b0) LInstrD = {1'b0, immCI, rds1, 3'b000, rds1, 7'b0010011}; // c.addi + 5'b01000: if (rds1 != 5'b0) + if (immCI[5:0] != 0) LInstrD = {1'b0, immCI, rds1, 3'b000, rds1, 7'b0010011}; // c.addi + else LInstrD = {1'b0, 25'b0, 7'b0010011}; // c.addi with imm = 0 is a HINT, treated as nop else if (immCI[5:0] == 6'b0) LInstrD = {1'b0, 25'b0, 7'b0010011}; // c.nop + else LInstrD = {1'b0, 25'b0, 7'b0010011}; // c.nop with imm != 0 is a HINT, treated as nop 5'b01001: if (P.XLEN==32) LInstrD = {1'b0, immCJ, 5'b00001, 7'b1101111}; // c.jal - else + else if (rds1 != 5'b0) LInstrD = {1'b0, immCI, rds1, 3'b000, rds1, 7'b0011011}; // c.addiw 5'b01010: if (rds1 != 5'b0) LInstrD = {1'b0, immCI, 5'b00000, 3'b000, rds1, 7'b0010011}; // c.li + else LInstrD = {1'b0, 25'b0, 7'b0010011}; // c.li with rd = 0 is a HINT, treated as nop 5'b01011: if (rds1 == 5'b00010) LInstrD = {1'b0, immCIASP, rds1, 3'b000, rds1, 7'b0010011}; // c.addi16sp else if (rds1 != 5'b0) LInstrD = {1'b0, immCILUI, rds1, 7'b0110111}; // c.lui - 5'b01100: if (instr16[11:10] == 2'b00) - LInstrD = {1'b0, 6'b000000, immSH, rds1p, 3'b101, rds1p, 7'b0010011}; // c.srli - else if (instr16[11:10] == 2'b01) - LInstrD = {1'b0, 6'b010000, immSH, rds1p, 3'b101, rds1p, 7'b0010011}; // c.srai - else if (instr16[11:10] == 2'b10) + else if (immCILUI[5:0] != 0) LInstrD = {1'b0, 25'b0, 7'b0010011}; // c.lui with rd = 0, imm!=0 is a HINT, treated as nop + 5'b01100: if (instr16[11:10] == 2'b00) begin + if (P.XLEN == 64 | ~immSH[5]) LInstrD = {1'b0, 6'b000000, immSH, rds1p, 3'b101, rds1p, 7'b0010011}; // c.srli; shamt[5] must be 0 in RV32C + end else if (instr16[11:10] == 2'b01) begin + if (P.XLEN == 64 | ~immSH[5]) LInstrD = {1'b0, 6'b010000, immSH, rds1p, 3'b101, rds1p, 7'b0010011}; // c.srai; shamt[5] must be 0 in RV32C + end else if (instr16[11:10] == 2'b10) LInstrD = {1'b0, immCI, rds1p, 3'b111, rds1p, 7'b0010011}; // c.andi else if (instr16[12:10] == 3'b011) if (instr16[6:5] == 2'b00) @@ -158,20 +163,23 @@ module decompress import cvw::*; #(parameter cvw_t P) ( 5'b01101: LInstrD = {1'b0, immCJ, 5'b00000, 7'b1101111}; // c.j 5'b01110: LInstrD = {1'b0, immCB[11:5], 5'b00000, rs1p, 3'b000, immCB[4:0], 7'b1100011}; // c.beqz 5'b01111: LInstrD = {1'b0, immCB[11:5], 5'b00000, rs1p, 3'b001, immCB[4:0], 7'b1100011}; // c.bnez - 5'b10000: LInstrD = {1'b0, 6'b000000, immSH, rds1, 3'b001, rds1, 7'b0010011}; // c.slli + 5'b10000: if (rds1 != 5'b0) begin + if (P.XLEN == 64 | ~immSH[5]) LInstrD = {1'b0, 6'b000000, immSH, rds1, 3'b001, rds1, 7'b0010011}; // c.slli; shamt[5] must be 0 in RV32C + end else if (immSH != 0) LInstrD = {1'b0, 25'b0, 7'b0010011}; // c.slli with rd = 0, immm != 0 is a HINT, treated as nop 5'b10001: if (P.ZCD_SUPPORTED) if (rds1 != 5'b0) LInstrD = {1'b0, immCILSPD, 5'b00010, 3'b011, rds1, 7'b0000111}; // c.fldsp 5'b10010: if (rds1 != 5'b0) LInstrD = {1'b0, immCILSP, 5'b00010, 3'b010, rds1, 7'b0000011}; // c.lwsp 5'b10011: if (P.XLEN == 32) begin if (P.ZCF_SUPPORTED) LInstrD = {1'b0, immCILSP, 5'b00010, 3'b010, rds1, 7'b0000111}; // c.flwsp - end else + end else if (rds1 != 5'b0) LInstrD = {1'b0, immCILSPD, 5'b00010, 3'b011, rds1, 7'b0000011}; // c.ldsp 5'b10100: if (instr16[12] == 0) - if (instr16[6:2] == 5'b00000) begin + if (rs2 == 5'b00000) begin if (rds1 != 5'b0) LInstrD = {1'b0, 7'b0000000, 5'b00000, rds1, 3'b000, 5'b00000, 7'b1100111}; // c.jr end else - LInstrD = {1'b0, 7'b0000000, rs2, 5'b00000, 3'b000, rds1, 7'b0110011}; // c.mv + if (rds1 != 5'b0) LInstrD = {1'b0, 7'b0000000, rs2, 5'b00000, 3'b000, rds1, 7'b0110011}; // c.mv + else LInstrD = {1'b0, 25'b0, 7'b0010011}; // c.mv with rd = 0 is a HINT, treated as nop else if (rs2 == 5'b00000) begin if (rds1 == 5'b00000) @@ -179,7 +187,8 @@ module decompress import cvw::*; #(parameter cvw_t P) ( else if (rds1 != 5'b0) LInstrD = {1'b0, 12'b0, rds1, 3'b000, 5'b00001, 7'b1100111}; // c.jalr end else - LInstrD = {1'b0, 7'b0000000, rs2, rds1, 3'b000, rds1, 7'b0110011}; // c.add + if (rds1 != 0) LInstrD = {1'b0, 7'b0000000, rs2, rds1, 3'b000, rds1, 7'b0110011}; // c.add + else LInstrD = {1'b0, 25'b0, 7'b0010011}; // c.add with rd = 0 is a HINT, treated as nop, even if it is a C.NTL 5'b10101: if (P.ZCD_SUPPORTED) LInstrD = {1'b0, immCSSD[11:5], rs2, 5'b00010, 3'b011, immCSSD[4:0], 7'b0100111}; // c.fsdsp 5'b10110: LInstrD = {1'b0, immCSS[11:5], rs2, 5'b00010, 3'b010, immCSS[4:0], 7'b0100011}; // c.swsp