From: Joshua Wise <joshua@rebirth.joshuawise.com>
Date: Wed, 14 Jan 2009 07:13:25 +0000 (-0500)
Subject: Issue: Add logic to defer a flush if need be (i.e., we're stalled at the time and... 
X-Git-Url: http://git.joshuawise.com/firearm.git/commitdiff_plain/c4e2ac3b3f80b9d92660c87009714362cdb7f875?hp=73e0b1b169d00c94c7538eb612780b09aa8f3b9c

Issue: Add logic to defer a flush if need be (i.e., we're stalled at the time and hence not allowed to change any other state).
---

diff --git a/Issue.v b/Issue.v
index 7b281a3..7815a08 100644
--- a/Issue.v
+++ b/Issue.v
@@ -282,8 +282,15 @@ module Issue(
 		waiting_cpsr = use_cpsr & (cpsr_inflight[0] | cpsr_inflight[1]);
 		waiting_regs = |(use_regs & (regs_inflight[0] | regs_inflight[1]));
 		
-		outstall = ((waiting && !inbubble) || stall) && !flush;	/* Happens in an always @*, because it is an exception. */
+		outstall = (waiting && !inbubble && !flush) || stall;	/* Happens in an always @*, because it is an exception. */
 	end
+
+	reg delayedflush = 0;
+	always @(posedge clk)
+		if (flush && outstall /* halp! I can't do it now, maybe later? */)
+			delayedflush <= 1;
+		else if (!outstall /* anything has been handled this time around */)
+			delayedflush <= 0;
 	
 	/* Actually do the issue. */
 	always @(posedge clk)
@@ -291,7 +298,7 @@ module Issue(
 		if (waiting)
 			$display("ISSUE: Stalling instruction %08x because %d/%d", insn, waiting_cpsr, waiting_regs);
 
-		if(flush)
+		if((flush || delayedflush) && !outstall)
 		begin
 			cpsr_inflight[0] = 1'b0;
 			cpsr_inflight[1] = 1'b0;