Fixed up NPC and Epoch handling.
This commit is contained in:
John Terrell
parent
9881cf00d4
commit
61d2a7cab4
GPG Key ID:
2E424258DD3731F4
@ -17,6 +17,8 @@ interface FetchStage_Ifc#(numeric type xlen);
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endinterface
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module mkFetchStage#(IsaCfg#(xlen) cfg)(FetchStage_Ifc#(xlen));
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Reg#(Epoch) epoch <- mkReg(defaultValue);
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Reg#(ProgramCounter#(xlen)) updatedPc <- mkRegU; // Holds the updated PC that is calculated when a fetch is issued
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// that is used to update the PC when the fetch completes.
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@ -37,7 +39,8 @@ module mkFetchStage#(IsaCfg#(xlen) cfg)(FetchStage_Ifc#(xlen));
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IF_ID#(xlen) if_id = defaultValue;
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if_id.common.pc = inflightMemoryRequest.Valid.address;
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if_id.common.isBubble = False;
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if_id.npc = updatedPc;
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if_id.npc = updatedPc + 4;
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if_id.epoch = epoch;
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if (!response.accessFault) begin
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if_id.common.ir.value = response.data;
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@ -73,10 +76,15 @@ module mkFetchStage#(IsaCfg#(xlen) cfg)(FetchStage_Ifc#(xlen));
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end else begin
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// No memory request is in flight...
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// Determine the PC the instruction will be fetchted from. It's either the calculated PC
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// Determine the PC the instruction will be fetched from. It's either the calculated PC
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// or a redirected PC (due to a branch, jump, exception, etc)
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ProgramCounter#(xlen) updatedPc_ = fromMaybe(pc_if.pc, pc_if.redirection);
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// If a redirection was specified, reflect that with a change in the epoch.
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if (isValid(pc_if.redirection)) begin
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epoch <= ~epoch;
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end
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// Check for a misaligned request
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if (updatedPc_[1:0] != 0) begin
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// Address request was misaligned...
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@ -40,6 +40,7 @@ module mkTopModule(Empty);
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dynamicAssert(!if_id.common.isBubble, "Fetch - Misaligned instruction trap check - common.isBubble");
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dynamicAssert(isValid(if_id.common.trap), "Fetch - Misaligned instruction trap check - contains trap");
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dynamicAssert(if_id.common.trap.Valid.cause == exception_INSTRUCTION_ADDRESS_MISALIGNED, "Fetch - Misaligned instruction trap check - cause is misaligned address");
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dynamicAssert(if_id.npc == defaultValue, "Fetch - Misaligned instruction trap check - NPC incorrect");
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end
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// Memory request denied trap (request submit)
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@ -74,13 +75,14 @@ module mkTopModule(Empty);
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3: begin
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pc_if.pc = 'h100;
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// The fetch should proceed and return a bubble.
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let if_id <- fetchStage32.step(pc_if);
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dynamicAssert(if_id.common.pc == pc_if.pc, "Fetch - Memory request denied trap check - common.pc");
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dynamicAssert(if_id.common.ir == defaultValue, "Fetch - Memory request denied trap check - common.ir");
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dynamicAssert(!if_id.common.isBubble, "Fetch - Memory request denied trap check - common.isBubble");
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dynamicAssert(isValid(if_id.common.trap), "Fetch - Memory request denied trap check - contains trap");
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dynamicAssert(if_id.common.trap.Valid.cause == exception_INSTRUCTION_ACCESS_FAULT, "Memory request denied trap check - cause is access fault");
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dynamicAssert(if_id.npc == 'h104, "Fetch - Misaligned instruction trap check - NPC incorrect");
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dynamicAssert(if_id.epoch == defaultValue, "Fetch - Misaligned instruction trap check - Verify epoch unchanged");
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end
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// Normal memory request (request submit)
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@ -115,16 +117,58 @@ module mkTopModule(Empty);
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6: begin
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pc_if.pc = 'h100;
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// The fetch should proceed and return a bubble.
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let if_id <- fetchStage32.step(pc_if);
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dynamicAssert(if_id.common.pc == pc_if.pc, "Fetch - Normal request - common.pc");
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dynamicAssert(!if_id.common.isBubble, "Fetch - Normal request - common.isBubble");
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dynamicAssert(!isValid(if_id.common.trap), "Fetch - Normal request - contains no trap");
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dynamicAssert(if_id.common.ir.value == 'haabb_ccdd, "Fetch - Normal request - contains expected instruction data");
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dynamicAssert(if_id.npc == 'h104, "Fetch - Normal request - NPC incorrect");
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dynamicAssert(if_id.epoch == defaultValue, "Fetch - Normal request - Verify epoch unchanged");
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end
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// Redirect handling check
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7: begin
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pc_if.pc = 'h100;
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pc_if.redirection = tagged Valid 'h8000;
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// The fetch should proceed and return a bubble.
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let if_id <- fetchStage32.step(pc_if);
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dynamicAssert(if_id == defaultValue, "Fetch - Redirect check - request should return a bubble");
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end
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8: begin
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pc_if.pc = 'h100;
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// Ensure the fetch returns a bubble while the memory request is in flight
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let if_id <- fetchStage32.step(pc_if);
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dynamicAssert(if_id == defaultValue, "Fetch - Redirect check - request should return a bubble while fetch is in flight");
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dynamicAssert(memoryRequests32.notEmpty, "Fetch - Redirect check - memory request queue should not be empty");
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let memoryRequest = memoryRequests32.first;
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memoryRequests32.deq;
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dynamicAssert(memoryRequest.address == 'h8000, "Fetch - Redirect check - memory request should have correct address");
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fetchStage32.memoryClient.response.put(ReadOnlyMemoryResponse {
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data: 'haabb_ccee,
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accessFault: False
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});
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end
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9: begin
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pc_if.pc = 'h100;
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// The fetch should proceed and return a bubble.
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let if_id <- fetchStage32.step(pc_if);
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dynamicAssert(if_id.common.pc == 'h8000, "Fetch - Redirect check - common.pc");
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dynamicAssert(!if_id.common.isBubble, "Fetch - Redirect check - common.isBubble");
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dynamicAssert(!isValid(if_id.common.trap), "Fetch - Redirect check - contains no trap");
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dynamicAssert(if_id.common.ir.value == 'haabb_ccee, "Fetch - Redirect check - contains expected instruction data");
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dynamicAssert(if_id.npc == 'h8004, "Fetch - Redirect check - NPC incorrect");
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dynamicAssert(if_id.epoch == 'h1, "Fetch - Redirect check - Verify epoch changed");
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end
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default: begin
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dynamicAssert(stepNumber == 7, "Fetch - not all tests run");
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dynamicAssert(stepNumber == 10, "Fetch - not all tests run");
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$display(">>>PASS");
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$finish();
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end
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@ -1,6 +1,11 @@
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import Trap::*;
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import DefaultValue::*;
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//
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// Epoch
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//
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typedef Bit#(1) Epoch;
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//
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// Instruction
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//
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@ -58,14 +63,14 @@ endinstance
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//
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typedef struct {
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PipelineRegisterCommon#(xlen) common;
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Bit#(1) epoch;
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Epoch epoch;
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ProgramCounter#(xlen) npc; // Next program counter
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} IF_ID#(numeric type xlen) deriving(Bits, Eq, FShow);
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instance DefaultValue #(IF_ID#(xlen));
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defaultValue = IF_ID {
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common: defaultValue,
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epoch: 'h-1,
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epoch: defaultValue,
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npc: defaultValue
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};
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endinstance
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@ -75,7 +80,7 @@ endinstance
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//
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typedef struct {
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PipelineRegisterCommon#(xlen) common;
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Bit#(1) epoch;
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Epoch epoch;
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ProgramCounter#(xlen) npc; // Next program counter
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Bit#(xlen) a; // Operand 1
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Bit#(xlen) b; // Operand 2
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@ -86,7 +91,7 @@ typedef struct {
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instance DefaultValue #(ID_EX#(xlen));
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defaultValue = ID_EX {
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common: defaultValue,
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epoch: 0,
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epoch: defaultValue,
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npc: defaultValue,
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a: 'h-1,
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b: 'h-1,
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