From 61b97e090df2d7c9ced5426bdd66321b75b86798 Mon Sep 17 00:00:00 2001
From: Peter Rugg <pdr32@cam.ac.uk>
Date: Tue, 19 May 2020 23:04:53 +0100
Subject: [PATCH] Fix CFromPtr common case

---
 src_Core/RISCY_OOO/procs/lib/CapChecks.bsvi |  2 +-
 src_Core/RISCY_OOO/procs/lib/Decode.bsv     |  4 ++--
 src_Core/RISCY_OOO/procs/lib/Exec.bsv       | 13 +++++--------
 src_Core/RISCY_OOO/procs/lib/ProcTypes.bsv  |  2 +-
 4 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/src_Core/RISCY_OOO/procs/lib/CapChecks.bsvi b/src_Core/RISCY_OOO/procs/lib/CapChecks.bsvi
index 6577c6d..981bbad 100644
--- a/src_Core/RISCY_OOO/procs/lib/CapChecks.bsvi
+++ b/src_Core/RISCY_OOO/procs/lib/CapChecks.bsvi
@@ -19,4 +19,4 @@
 `CAP_CHECK_FIELD(src1_perm_subset_src2,"src1_perm_subset_src2")
 `CAP_CHECK_FIELD(src1_derivable,"src1_derivable")
 `CAP_CHECK_FIELD(scr_read_only,"scr_read_only")
-`CAP_CHECK_FIELD(skip_if_src1_zero,"skip_if_src1_zero")
+`CAP_CHECK_FIELD(cfromptr_bypass,"cfromptr_bypass")
diff --git a/src_Core/RISCY_OOO/procs/lib/Decode.bsv b/src_Core/RISCY_OOO/procs/lib/Decode.bsv
index 4f922cf..a157460 100755
--- a/src_Core/RISCY_OOO/procs/lib/Decode.bsv
+++ b/src_Core/RISCY_OOO/procs/lib/Decode.bsv
@@ -1179,7 +1179,7 @@ function DecodeResult decode(Instruction inst, Bool cap_mode);
                             // are zero in Exec
                             dInst.capChecks.src2_tag = True;
                             dInst.capChecks.src2_unsealed = True;
-                            dInst.capChecks.skip_if_src1_zero = True;
+                            dInst.capChecks.cfromptr_bypass = True;
 
                             dInst.iType = Cap;
                             regs.dst = Valid(tagged Gpr rd);
@@ -1187,7 +1187,7 @@ function DecodeResult decode(Instruction inst, Bool cap_mode);
                             regs.src2 = rs1 == 0 ? Invalid : Valid (tagged Gpr rs1);
                             dInst.scr = rs1 == 0 ? Valid(SCR_DDC) : Invalid;
                             dInst.imm = Invalid;
-                            dInst.capFunc = CapModify (SetAddr (Src1Addr));
+                            dInst.capFunc = CapModify (FromPtr);
                         end
                         f7_cap_CSub: begin
                             // CSub is just a riscv subtract
diff --git a/src_Core/RISCY_OOO/procs/lib/Exec.bsv b/src_Core/RISCY_OOO/procs/lib/Exec.bsv
index 1b523ba..ed042a4 100755
--- a/src_Core/RISCY_OOO/procs/lib/Exec.bsv
+++ b/src_Core/RISCY_OOO/procs/lib/Exec.bsv
@@ -190,7 +190,7 @@ endfunction
 function CapPipe capModify(CapPipe a, CapPipe b, CapModifyFunc func);
     CapPipe res = (case(func) matches
             tagged ModifyOffset .offsetOp :
-                modifyOffset(a, getAddr(b), offsetOp == IncOffset).value;
+                modifyOffset(a, getAddr(b), offsetOp == IncOffset).value; // TODO check for unrepresentability
             tagged SetBounds .boundsOp    :
                 setBoundsALU(a, getAddr(b), boundsOp);
             tagged SpecialRW .scrType     :
@@ -203,7 +203,7 @@ function CapPipe capModify(CapPipe a, CapPipe b, CapModifyFunc func);
                  endcase
             tagged SetAddr .addrSource    :
                 if (addrSource == Src1Type && (getKind(a) == UNSEALED)) return nullWithAddr(-1); // TODO correct behaviour around reserved types
-                else return setAddr(b, (addrSource == Src1Type) ? zeroExtend(getKind(a).SEALED_WITH_TYPE) : getAddr(a) ).value;
+                else return setAddr(b, (addrSource == Src1Type) ? zeroExtend(getKind(a).SEALED_WITH_TYPE) : getAddr(a) ).value; // TODO check for unrepresentability
             tagged Seal                   :
                 setKind(a, SEALED_WITH_TYPE (truncate(getAddr(b))));
             tagged Unseal .src            :
@@ -212,16 +212,14 @@ function CapPipe capModify(CapPipe a, CapPipe b, CapModifyFunc func);
                 setPerms(a, pack(getPerms(a)) & truncate(getAddr(b)));
             tagged SetFlags               :
                 setFlags(a, truncate(getAddr(b)));
-            //tagged FromPtr                :
-            //     error("FromPtr not yet implemented");
+            tagged FromPtr                :
+                (getAddr(a) == 0 ? nullCap : setOffset(b, getAddr(a)).value); // TODO check for unrepresentability
             tagged BuildCap               :
                 setKind(setValidCap(a, True),UNSEALED); // TODO preserve sentries
             tagged Move                   :
                 a;
             tagged ClearTag               :
                 setValidCap(a, False);
-            //tagged CJALR                  :
-            //    error("CJALR not yet implemented");
             default: ?;
         endcase);
     return res;
@@ -353,9 +351,8 @@ function ExecResult basicExec(DecodedInst dInst, CapPipe rVal1, CapPipe rVal2, C
     Maybe#(BoundsCheck) boundsCheck = prepareBoundsCheck(rVal1, aluVal2, pcc,
                                                          nullCap, 0, 0, // These three are only used in the memory pipe
                                                          dInst.capChecks);
-    if (dInst.capChecks.skip_if_src1_zero && getAddr(rVal1) == 0) begin
+    if (dInst.capChecks.cfromptr_bypass && getAddr(rVal1) == 0) begin
         capException = Invalid;
-        cap_alu_result = nullCap;
     end
 
     cf.nextPc = setKind(cf.nextPc, UNSEALED);
diff --git a/src_Core/RISCY_OOO/procs/lib/ProcTypes.bsv b/src_Core/RISCY_OOO/procs/lib/ProcTypes.bsv
index 9f0c314..96bbf19 100755
--- a/src_Core/RISCY_OOO/procs/lib/ProcTypes.bsv
+++ b/src_Core/RISCY_OOO/procs/lib/ProcTypes.bsv
@@ -283,7 +283,7 @@ typedef union tagged {
     void BuildCap;
     void Move;
     void ClearTag;
-    void CJALR;
+    void FromPtr;
 } CapModifyFunc deriving(Bits, Eq, FShow);
 
 typedef union tagged {