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Mips assembler: .set reorder support
Mips have delayslots for certain instructions like jumps and branches. These are instructions that follow the branch or jump and are executed before the jump or branch is completed. Early Mips compilers could not cope with delayslots and left them up to the assembler. The assembler would fill the delayslots with the appropriate instruction, usually just a nop to allow correct runtime behavior. The default behavior for this is set with .set reorder. To tell the assembler that you don't want it to mess with the delayslot one used .set noreorder. For backwards compatibility we need to support .set reorder and have it be the default behavior in the assembler. Our support for it is to insert a NOP directly after an instruction with a delayslot when in .set reorder mode. Contributer: Vladimir Medic git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180584 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -418,6 +418,19 @@ bool MipsAsmParser::processInstruction(MCInst &Inst, SMLoc IDLoc,
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SmallVectorImpl<MCInst> &Instructions) {
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SmallVectorImpl<MCInst> &Instructions) {
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const MCInstrDesc &MCID = getInstDesc(Inst.getOpcode());
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const MCInstrDesc &MCID = getInstDesc(Inst.getOpcode());
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Inst.setLoc(IDLoc);
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Inst.setLoc(IDLoc);
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if (MCID.hasDelaySlot() && Options.isReorder()) {
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// If this instruction has a delay slot and .set reorder is active,
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// emit a NOP after it.
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Instructions.push_back(Inst);
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MCInst NopInst;
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NopInst.setOpcode(Mips::SLL);
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NopInst.addOperand(MCOperand::CreateReg(Mips::ZERO));
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NopInst.addOperand(MCOperand::CreateReg(Mips::ZERO));
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NopInst.addOperand(MCOperand::CreateImm(0));
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Instructions.push_back(NopInst);
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return false;
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}
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if (MCID.mayLoad() || MCID.mayStore()) {
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if (MCID.mayLoad() || MCID.mayStore()) {
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// Check the offset of memory operand, if it is a symbol
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// Check the offset of memory operand, if it is a symbol
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// reference or immediate we may have to expand instructions.
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// reference or immediate we may have to expand instructions.
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@ -1,11 +1,20 @@
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# RUN: llvm-mc -show-encoding -triple mips-unknown-unknown %s | FileCheck %s
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# RUN: llvm-mc -show-encoding -triple mips-unknown-unknown %s | FileCheck %s
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#
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#
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# CHECK: .text
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# CHECK: $BB0_2:
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$BB0_2:
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$BB0_2:
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.ent directives_test
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.ent directives_test
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.frame $sp,0,$ra
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.frame $sp,0,$ra
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.mask 0x00000000,0
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.mask 0x00000000,0
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.fmask 0x00000000,0
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.fmask 0x00000000,0
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# CHECK: b 1332 # encoding: [0x10,0x00,0x01,0x4d]
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# CHECK: j 1328 # encoding: [0x08,0x00,0x01,0x4c]
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# CHECK: jal 1328 # encoding: [0x0c,0x00,0x01,0x4c]
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.set noreorder
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.set noreorder
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b 1332
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j 1328
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jal 1328
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.set nomacro
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.set nomacro
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.set noat
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.set noat
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$JTI0_0:
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$JTI0_0:
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@ -15,7 +24,16 @@ $JTI0_0:
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# CHECK-NEXT: .4byte 2013265916
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# CHECK-NEXT: .4byte 2013265916
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.set at=$12
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.set at=$12
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.set macro
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.set macro
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# CHECK: b 1332 # encoding: [0x10,0x00,0x01,0x4d]
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# CHECK: nop # encoding: [0x00,0x00,0x00,0x00]
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# CHECK: j 1328 # encoding: [0x08,0x00,0x01,0x4c]
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# CHECK: nop # encoding: [0x00,0x00,0x00,0x00]
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# CHECK: jal 1328 # encoding: [0x0c,0x00,0x01,0x4c]
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# CHECK: nop # encoding: [0x00,0x00,0x00,0x00]
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.set reorder
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.set reorder
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b 1332
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j 1328
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jal 1328
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.set at=$a0
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.set at=$a0
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.set STORE_MASK,$t7
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.set STORE_MASK,$t7
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.set FPU_MASK,$f7
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.set FPU_MASK,$f7
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