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authorGabe Black <gblack@eecs.umich.edu>2010-06-02 12:58:02 -0500
committerGabe Black <gblack@eecs.umich.edu>2010-06-02 12:58:02 -0500
commit98693436368ef671681859d95f6bc4a0542a6a37 (patch)
treeb2380bcc0142069996f78e04c31df08ed7ade47a /src
parenta6c1c8debb523e94312d7e5ff25625b9638efe74 (diff)
downloadgem5-98693436368ef671681859d95f6bc4a0542a6a37.tar.xz
ARM: Implement branch instructions external to the decoder.
Diffstat (limited to 'src')
-rw-r--r--src/arch/arm/isa/decoder/arm.isa8
-rw-r--r--src/arch/arm/isa/insts/branch.isa175
-rw-r--r--src/arch/arm/isa/insts/insts.isa3
-rw-r--r--src/arch/arm/isa/operands.isa3
4 files changed, 185 insertions, 4 deletions
diff --git a/src/arch/arm/isa/decoder/arm.isa b/src/arch/arm/isa/decoder/arm.isa
index 8a5ba3e43..717bd1857 100644
--- a/src/arch/arm/isa/decoder/arm.isa
+++ b/src/arch/arm/isa/decoder/arm.isa
@@ -129,7 +129,7 @@ format DataOp {
}
}
0x1: decode OPCODE {
- 0x9: BranchExchange::bx({{ }});
+ 0x9: BranchExchange::oldbx({{ }});
0xb: PredOp::clz({{
Rd = ((Rm == 0) ? 32 : (31 - findMsbSet(Rm)));
}});
@@ -138,7 +138,7 @@ format DataOp {
0x9: WarnUnimpl::bxj();
}
0x3: decode OPCODE {
- 0x9: BranchExchange::blx({{ }}, Link);
+ 0x9: BranchExchange::oldblx({{ }}, Link);
}
0x5: decode OPCODE {
0x8: WarnUnimpl::qadd();
@@ -265,8 +265,8 @@ format DataOp {
0x4: ArmMacroMem::armMacroMem();
0x5: decode OPCODE_24 {
// Branch (and Link) Instructions
- 0: Branch::b({{ }});
- 1: Branch::bl({{ }}, Link);
+ 0: Branch::oldb({{ }});
+ 1: Branch::oldbl({{ }}, Link);
}
0x6: decode CPNUM {
0xb: decode LOADOP {
diff --git a/src/arch/arm/isa/insts/branch.isa b/src/arch/arm/isa/insts/branch.isa
new file mode 100644
index 000000000..71a98053e
--- /dev/null
+++ b/src/arch/arm/isa/insts/branch.isa
@@ -0,0 +1,175 @@
+// -*- mode:c++ -*-
+
+// Copyright (c) 2010 ARM Limited
+// All rights reserved
+//
+// The license below extends only to copyright in the software and shall
+// not be construed as granting a license to any other intellectual
+// property including but not limited to intellectual property relating
+// to a hardware implementation of the functionality of the software
+// licensed hereunder. You may use the software subject to the license
+// terms below provided that you ensure that this notice is replicated
+// unmodified and in its entirety in all distributions of the software,
+// modified or unmodified, in source code or in binary form.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met: redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer;
+// redistributions in binary form must reproduce the above copyright
+// notice, this list of conditions and the following disclaimer in the
+// documentation and/or other materials provided with the distribution;
+// neither the name of the copyright holders nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+// Authors: Gabe Black
+
+let {{
+
+ header_output = ""
+ decoder_output = ""
+ exec_output = ""
+
+ # B, BL
+ for (mnem, link) in (("b", False), ("bl", True)):
+ bCode = '''
+ Addr PC = readPC(xc);
+ NPC = ((PC + imm) & mask(32)) | (PC & ~mask(32));
+ '''
+ if (link):
+ bCode += '''
+ Addr tBit = PC & (ULL(1) << PcTBitShift);
+ if (!tBit)
+ LR = PC - 4;
+ else
+ LR = PC | 1;
+ '''
+
+ bIop = InstObjParams(mnem, mnem.capitalize(), "BranchImmCond",
+ {"code": bCode,
+ "predicate_test": predicateTest})
+ header_output += BranchImmCondDeclare.subst(bIop)
+ decoder_output += BranchImmCondConstructor.subst(bIop)
+ exec_output += PredOpExecute.subst(bIop)
+
+ # BX, BLX
+ blxCode = '''
+ Addr PC = readPC(xc);
+ Addr tBit = PC & (ULL(1) << PcTBitShift);
+ // Other than the assert below, jBit isn't used.
+#if !defined(NDEBUG)
+ Addr jBit = PC & (ULL(1) << PcJBitShift);
+#endif
+ // X isn't permitted in ThumbEE mode. We shouldn't be in jazzelle mode?
+ assert(!jBit);
+ bool arm = !tBit;
+ arm = arm; // In case it's not used otherwise.
+ Addr tempPc = ((%(newPC)s) & mask(32)) | (PC & ~mask(32));
+ %(link)s
+ // Switch modes
+ %(branch)s
+ '''
+
+ blxList = (("blx", True, True),
+ ("blx", False, True),
+ ("bx", False, False))
+
+ for (mnem, imm, link) in blxList:
+ Name = mnem.capitalize()
+ if imm and link: #blx with imm
+ branchStr = "FNPC = tempPc ^ (ULL(1) << PcTBitShift);"
+ else:
+ branchStr = "IWNPC = tempPc ^ (ULL(1) << PcTBitShift);"
+
+ if imm:
+ Name += "Imm"
+ # Since we're switching ISAs, the target ISA will be the opposite
+ # of the current ISA. !arm is whether the target is ARM.
+ newPC = '(!arm ? (roundDown(PC, 4) + imm) : (PC + imm))'
+ base = "BranchImm"
+ declare = BranchImmDeclare
+ constructor = BranchImmConstructor
+ else:
+ Name += "Reg"
+ newPC = '(PC & PcModeMask) | Op1'
+ base = "BranchRegCond"
+ declare = BranchRegCondDeclare
+ constructor = BranchRegCondConstructor
+ if link and imm:
+ linkStr = '''
+ // The immediate version of the blx thumb instruction
+ // is 32 bits wide, but "next pc" doesn't reflect that
+ // so we don't want to substract 2 from it at this point
+ if (arm)
+ LR = PC - 4;
+ else
+ LR = PC | 1;
+ '''
+ elif link:
+ linkStr = '''
+ if (arm)
+ LR = PC - 4;
+ else
+ LR = (PC - 2) | 1;
+ '''
+ else:
+ linkStr = ""
+ code = blxCode % {"link": linkStr,
+ "newPC": newPC,
+ "branch": branchStr}
+ blxIop = InstObjParams(mnem, Name, base,
+ {"code": code,
+ "predicate_test": predicateTest})
+ header_output += declare.subst(blxIop)
+ decoder_output += constructor.subst(blxIop)
+ exec_output += PredOpExecute.subst(blxIop)
+
+ #Ignore BXJ for now
+
+ #CBNZ, CBZ. These are always unconditional as far as predicates
+ for (mnem, test) in (("cbz", "=="), ("cbnz", "!=")):
+ code = '''
+ Addr PC = readPC(xc);
+ NPC = ((PC + imm) & mask(32)) | (PC & ~mask(32));
+ '''
+ predTest = "Op1 %(test)s 0" % {"test": test}
+ iop = InstObjParams(mnem, mnem.capitalize(), "BranchImmReg",
+ {"code": code, "predicate_test": predTest})
+ header_output += BranchImmRegDeclare.subst(iop)
+ decoder_output += BranchImmRegConstructor.subst(iop)
+ exec_output += PredOpExecute.subst(iop)
+
+ #TBB, TBH
+ for isTbh in (0, 1):
+ if isTbh:
+ eaCode = "EA = Op1 + Op2 * 2"
+ accCode = "NPC = readPC(xc) + 2 * (Mem.uh);"
+ mnem = "tbh"
+ else:
+ eaCode = "EA = Op1 + Op2"
+ accCode = "NPC = readPC(xc) + 2 * (Mem.ub);"
+ mnem = "tbb"
+ eaCode = "unsigned memAccessFlags = 0;\n" + eaCode
+ iop = InstObjParams(mnem, mnem.capitalize(), "BranchRegReg",
+ {'ea_code': eaCode,
+ 'memacc_code': accCode,
+ 'predicate_test': predicateTest})
+ header_output += BranchTableDeclare.subst(iop)
+ decoder_output += BranchRegRegConstructor.subst(iop)
+ exec_output += LoadExecute.subst(iop) + \
+ LoadInitiateAcc.subst(iop) + \
+ LoadCompleteAcc.subst(iop)
+}};
diff --git a/src/arch/arm/isa/insts/insts.isa b/src/arch/arm/isa/insts/insts.isa
index 4168d39b5..a7a96a51c 100644
--- a/src/arch/arm/isa/insts/insts.isa
+++ b/src/arch/arm/isa/insts/insts.isa
@@ -54,3 +54,6 @@
//Data processing instructions
##include "data.isa"
+
+//Branches
+##include "branch.isa"
diff --git a/src/arch/arm/isa/operands.isa b/src/arch/arm/isa/operands.isa
index 3f331832c..ab4d95d47 100644
--- a/src/arch/arm/isa/operands.isa
+++ b/src/arch/arm/isa/operands.isa
@@ -68,6 +68,7 @@ let {{
readNPC = 'xc->readNextPC() & ~PcModeMask'
writeNPC = 'setNextPC(xc, %(final_val)s)'
writeIWNPC = 'setIWNextPC(xc, %(final_val)s)'
+ forceNPC = 'xc->setNextPC(%(final_val)s)'
}};
def operands {{
@@ -125,6 +126,8 @@ def operands {{
'Fpexc': ('ControlReg', 'uw', 'MISCREG_FPEXC', None, 45),
'NPC': ('NPC', 'ud', None, (None, None, 'IsControl'), 51,
readNPC, writeNPC),
+ 'FNPC': ('NPC', 'ud', None, (None, None, 'IsControl'), 51,
+ readNPC, forceNPC),
'IWNPC': ('NPC', 'ud', None, (None, None, 'IsControl'), 51,
readNPC, writeIWNPC),
}};