commit 9f887b7634e3ec299e2c0b8ac8b982f7c99f9622
author Gabe Black <gabeblack@google.com> Sun Aug 30 01:38:47 2020 -0700
committer Gabe Black <gabeblack@google.com> Tue Sep 15 08:03:26 2020 +0000
tree 66e1854cf8c8d91732085d1a2b865e7976b4d173
parent d64465c02482fc2afa4c1467650976856c9a440a

mips,cpu: Get rid of the IsIprAccess StaticInst flag.

This was set by MIPS in two places, I think largely just because it was
available. This flag refers to IPRs which are an Alpha concept. In the
O3 CPU, IsIprAccess was used as a possible indicator to determine if an
instruction IsSerializeBefore, but we've already got a flag for that. In
the minor CPU, which hasn't been made to work with MIPS as far as I
know, it was used in a condition but not mentioned in the comment
alongside the condition. I think there it was added for the sake of
Alpha.

This change eliminates that flag and removes it from the O3 and minor
CPUs. In the MIPS ISA description, the instructions that were marked as
IsIprAccess have now been marked as IsSerializeBefore since, if there
was a real reason for them to be marked as IsIprAccess, it would have
been to get it them to work in O3, and there IsSerializeBefore gets
equivalent behavior.

Change-Id: Ia874cde12fa70b998d3e638458f13d69798d40b7
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/33739
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>

src/arch/mips/isa/decoder.isa

diff --git a/src/arch/mips/isa/decoder.isa b/src/arch/mips/isa/decoder.isa
index 76453b0..73e2b5d 100644
--- a/src/arch/mips/isa/decoder.isa
+++ b/src/arch/mips/isa/decoder.isa
@@ -174,10 +174,10 @@
 
             0x2: decode FUNCTION_LO {
                 0x0: HiLoRsSelOp::mfhi({{ Rd = HI_RS_SEL; }},
-                             IntMultOp, IsIprAccess);
+                             IntMultOp, IsSerializeBefore);
                 0x1: HiLoRdSelOp::mthi({{ HI_RD_SEL = Rs; }});
                 0x2: HiLoRsSelOp::mflo({{ Rd = LO_RS_SEL; }},
-                             IntMultOp, IsIprAccess);
+                             IntMultOp, IsSerializeBefore);
                 0x3: HiLoRdSelOp::mtlo({{ LO_RD_SEL = Rs; }});
             }
 

src/cpu/StaticInstFlags.py

diff --git a/src/cpu/StaticInstFlags.py b/src/cpu/StaticInstFlags.py
index b70f919..151074e 100644
--- a/src/cpu/StaticInstFlags.py
+++ b/src/cpu/StaticInstFlags.py
@@ -89,7 +89,6 @@
         'IsNonSpeculative', # Should not be executed speculatively
         'IsQuiesce',        # Is a quiesce instruction
 
-        'IsIprAccess',      # Accesses IPRs
         'IsUnverifiable',   # Can't be verified by a checker
 
         'IsSyscall',        # Causes a system call to be emulated in syscall

src/cpu/base_dyn_inst.hh

diff --git a/src/cpu/base_dyn_inst.hh b/src/cpu/base_dyn_inst.hh
index bfe0492..00639ad 100644
--- a/src/cpu/base_dyn_inst.hh
+++ b/src/cpu/base_dyn_inst.hh
@@ -557,7 +557,6 @@
     bool isWriteBarrier() const { return staticInst->isWriteBarrier(); }
     bool isNonSpeculative() const { return staticInst->isNonSpeculative(); }
     bool isQuiesce() const { return staticInst->isQuiesce(); }
-    bool isIprAccess() const { return staticInst->isIprAccess(); }
     bool isUnverifiable() const { return staticInst->isUnverifiable(); }
     bool isSyscall() const { return staticInst->isSyscall(); }
     bool isMacroop() const { return staticInst->isMacroop(); }

src/cpu/minor/execute.cc

diff --git a/src/cpu/minor/execute.cc b/src/cpu/minor/execute.cc
index 45ca002..f8db523 100644
--- a/src/cpu/minor/execute.cc
+++ b/src/cpu/minor/execute.cc
@@ -224,8 +224,7 @@
         !inst->isFault() &&
         inst->isLastOpInInst() &&
         (inst->staticInst->isSerializeAfter() ||
-         inst->staticInst->isSquashAfter() ||
-         inst->staticInst->isIprAccess());
+         inst->staticInst->isSquashAfter());
 
     DPRINTF(Branch, "tryToBranch before: %s after: %s%s\n",
         pc_before, target, (force_branch ? " (forcing)" : ""));

src/cpu/o3/rename_impl.hh

diff --git a/src/cpu/o3/rename_impl.hh b/src/cpu/o3/rename_impl.hh
index 1cbe87a..052012e 100644
--- a/src/cpu/o3/rename_impl.hh
+++ b/src/cpu/o3/rename_impl.hh
@@ -684,8 +684,7 @@
         // instructions.  This is mainly due to lack of support for
         // out-of-order operations of either of those classes of
         // instructions.
-        if ((inst->isIprAccess() || inst->isSerializeBefore()) &&
-            !inst->isSerializeHandled()) {
+        if (inst->isSerializeBefore() && !inst->isSerializeHandled()) {
             DPRINTF(Rename, "Serialize before instruction encountered.\n");
 
             if (!inst->isTempSerializeBefore()) {

src/cpu/static_inst.hh

diff --git a/src/cpu/static_inst.hh b/src/cpu/static_inst.hh
index e536b84..353c0e3 100644
--- a/src/cpu/static_inst.hh
+++ b/src/cpu/static_inst.hh
@@ -190,7 +190,6 @@
     bool isWriteBarrier() const { return flags[IsWriteBarrier]; }
     bool isNonSpeculative() const { return flags[IsNonSpeculative]; }
     bool isQuiesce() const { return flags[IsQuiesce]; }
-    bool isIprAccess() const { return flags[IsIprAccess]; }
     bool isUnverifiable() const { return flags[IsUnverifiable]; }
     bool isSyscall() const { return flags[IsSyscall]; }
     bool isMacroop() const { return flags[IsMacroop]; }