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merged 3 commits into from
Apr 5, 2025
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[RISCV] Relax out of range Xqcibi conditional branches #134336

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dd53c83
[RISCV] Relax out of range Xqcibi conditional branches
svs-quic Apr 4, 2025
16a3d43
Fix test comment
svs-quic Apr 4, 2025
8267424
Merge branch 'main' into relaxlb
svs-quic Apr 5, 2025
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36 changes: 36 additions & 0 deletions llvm/lib/Target/RISCV/MCTargetDesc/RISCVAsmBackend.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -198,6 +198,30 @@ static unsigned getRelaxedOpcode(unsigned Op) {
return RISCV::PseudoLongBLTU;
case RISCV::BGEU:
return RISCV::PseudoLongBGEU;
case RISCV::QC_BEQI:
return RISCV::PseudoLongQC_BEQI;
case RISCV::QC_BNEI:
return RISCV::PseudoLongQC_BNEI;
case RISCV::QC_BLTI:
return RISCV::PseudoLongQC_BLTI;
case RISCV::QC_BGEI:
return RISCV::PseudoLongQC_BGEI;
case RISCV::QC_BLTUI:
return RISCV::PseudoLongQC_BLTUI;
case RISCV::QC_BGEUI:
return RISCV::PseudoLongQC_BGEUI;
case RISCV::QC_E_BEQI:
return RISCV::PseudoLongQC_E_BEQI;
case RISCV::QC_E_BNEI:
return RISCV::PseudoLongQC_E_BNEI;
case RISCV::QC_E_BLTI:
return RISCV::PseudoLongQC_E_BLTI;
case RISCV::QC_E_BGEI:
return RISCV::PseudoLongQC_E_BGEI;
case RISCV::QC_E_BLTUI:
return RISCV::PseudoLongQC_E_BLTUI;
case RISCV::QC_E_BGEUI:
return RISCV::PseudoLongQC_E_BGEUI;
}
}

Expand All @@ -224,6 +248,18 @@ void RISCVAsmBackend::relaxInstruction(MCInst &Inst,
case RISCV::BGE:
case RISCV::BLTU:
case RISCV::BGEU:
case RISCV::QC_BEQI:
case RISCV::QC_BNEI:
case RISCV::QC_BLTI:
case RISCV::QC_BGEI:
case RISCV::QC_BLTUI:
case RISCV::QC_BGEUI:
case RISCV::QC_E_BEQI:
case RISCV::QC_E_BNEI:
case RISCV::QC_E_BLTI:
case RISCV::QC_E_BGEI:
case RISCV::QC_E_BLTUI:
case RISCV::QC_E_BGEUI:
Res.setOpcode(getRelaxedOpcode(Inst.getOpcode()));
Res.addOperand(Inst.getOperand(0));
Res.addOperand(Inst.getOperand(1));
Expand Down
97 changes: 97 additions & 0 deletions llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCCodeEmitter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -68,6 +68,10 @@ class RISCVMCCodeEmitter : public MCCodeEmitter {
SmallVectorImpl<MCFixup> &Fixups,
const MCSubtargetInfo &STI) const;

void expandQCLongCondBrImm(const MCInst &MI, SmallVectorImpl<char> &CB,
SmallVectorImpl<MCFixup> &Fixups,
const MCSubtargetInfo &STI, unsigned Size) const;

/// TableGen'erated function for getting the binary encoding for an
/// instruction.
uint64_t getBinaryCodeForInstr(const MCInst &MI,
Expand Down Expand Up @@ -240,6 +244,30 @@ static unsigned getInvertedBranchOp(unsigned BrOp) {
return RISCV::BGEU;
case RISCV::PseudoLongBGEU:
return RISCV::BLTU;
case RISCV::PseudoLongQC_BEQI:
return RISCV::QC_BNEI;
case RISCV::PseudoLongQC_BNEI:
return RISCV::QC_BEQI;
case RISCV::PseudoLongQC_BLTI:
return RISCV::QC_BGEI;
case RISCV::PseudoLongQC_BGEI:
return RISCV::QC_BLTI;
case RISCV::PseudoLongQC_BLTUI:
return RISCV::QC_BGEUI;
case RISCV::PseudoLongQC_BGEUI:
return RISCV::QC_BLTUI;
case RISCV::PseudoLongQC_E_BEQI:
return RISCV::QC_E_BNEI;
case RISCV::PseudoLongQC_E_BNEI:
return RISCV::QC_E_BEQI;
case RISCV::PseudoLongQC_E_BLTI:
return RISCV::QC_E_BGEI;
case RISCV::PseudoLongQC_E_BGEI:
return RISCV::QC_E_BLTI;
case RISCV::PseudoLongQC_E_BLTUI:
return RISCV::QC_E_BGEUI;
case RISCV::PseudoLongQC_E_BGEUI:
return RISCV::QC_E_BLTUI;
}
}

Expand Down Expand Up @@ -305,6 +333,57 @@ void RISCVMCCodeEmitter::expandLongCondBr(const MCInst &MI,
}
}

// Expand PseudoLongQC_(E_)Bxxx to an inverted conditional branch and an
// unconditional jump.
void RISCVMCCodeEmitter::expandQCLongCondBrImm(const MCInst &MI,
SmallVectorImpl<char> &CB,
SmallVectorImpl<MCFixup> &Fixups,
const MCSubtargetInfo &STI,
unsigned Size) const {
MCRegister SrcReg1 = MI.getOperand(0).getReg();
auto BrImm = MI.getOperand(1).getImm();
MCOperand SrcSymbol = MI.getOperand(2);
unsigned Opcode = MI.getOpcode();
uint32_t Offset;
unsigned InvOpc = getInvertedBranchOp(Opcode);
// Emit inverted conditional branch with offset:
// 8 (QC.BXXX(4) + JAL(4))
// or
// 10 (QC.E.BXXX(6) + JAL(4)).
if (Size == 4) {
MCInst TmpBr =
MCInstBuilder(InvOpc).addReg(SrcReg1).addImm(BrImm).addImm(8);
uint32_t BrBinary = getBinaryCodeForInstr(TmpBr, Fixups, STI);
support::endian::write(CB, BrBinary, llvm::endianness::little);
} else {
MCInst TmpBr =
MCInstBuilder(InvOpc).addReg(SrcReg1).addImm(BrImm).addImm(10);
uint64_t BrBinary =
getBinaryCodeForInstr(TmpBr, Fixups, STI) & 0xffff'ffff'ffffu;
SmallVector<char, 8> Encoding;
support::endian::write(Encoding, BrBinary, llvm::endianness::little);
assert(Encoding[6] == 0 && Encoding[7] == 0 &&
"Unexpected encoding for 48-bit instruction");
Encoding.truncate(6);
CB.append(Encoding);
}
Offset = Size;
// Save the number fixups.
size_t FixupStartIndex = Fixups.size();
// Emit an unconditional jump to the destination.
MCInst TmpJ =
MCInstBuilder(RISCV::JAL).addReg(RISCV::X0).addOperand(SrcSymbol);
uint32_t JBinary = getBinaryCodeForInstr(TmpJ, Fixups, STI);
support::endian::write(CB, JBinary, llvm::endianness::little);
// Drop any fixup added so we can add the correct one.
Fixups.resize(FixupStartIndex);
if (SrcSymbol.isExpr()) {
Fixups.push_back(MCFixup::create(Offset, SrcSymbol.getExpr(),
MCFixupKind(RISCV::fixup_riscv_jal),
MI.getLoc()));
}
}

void RISCVMCCodeEmitter::encodeInstruction(const MCInst &MI,
SmallVectorImpl<char> &CB,
SmallVectorImpl<MCFixup> &Fixups,
Expand Down Expand Up @@ -339,6 +418,24 @@ void RISCVMCCodeEmitter::encodeInstruction(const MCInst &MI,
expandLongCondBr(MI, CB, Fixups, STI);
MCNumEmitted += 2;
return;
case RISCV::PseudoLongQC_BEQI:
case RISCV::PseudoLongQC_BNEI:
case RISCV::PseudoLongQC_BLTI:
case RISCV::PseudoLongQC_BGEI:
case RISCV::PseudoLongQC_BLTUI:
case RISCV::PseudoLongQC_BGEUI:
expandQCLongCondBrImm(MI, CB, Fixups, STI, 4);
MCNumEmitted += 2;
return;
case RISCV::PseudoLongQC_E_BEQI:
case RISCV::PseudoLongQC_E_BNEI:
case RISCV::PseudoLongQC_E_BLTI:
case RISCV::PseudoLongQC_E_BGEI:
case RISCV::PseudoLongQC_E_BLTUI:
case RISCV::PseudoLongQC_E_BGEUI:
expandQCLongCondBrImm(MI, CB, Fixups, STI, 6);
MCNumEmitted += 2;
return;
case RISCV::PseudoTLSDESCCall:
expandTLSDESCCall(MI, CB, Fixups, STI);
MCNumEmitted += 1;
Expand Down
33 changes: 33 additions & 0 deletions llvm/lib/Target/RISCV/RISCVInstrInfoXqci.td
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Original file line number Diff line number Diff line change
Expand Up @@ -1152,6 +1152,39 @@ let EmitPriority = 0 in {
} // EmitPriority = 0
} // Predicates = [HasVendorXqcilo, IsRV32]

//===----------------------------------------------------------------------===//
// Pseudo-instructions
//===----------------------------------------------------------------------===//

class LongBcciPseudo<DAGOperand InTyImm, int size>
: Pseudo<(outs), (ins GPR:$rs1, InTyImm:$imm, simm21_lsb0_jal:$imm20), []>
{
let Size = size;
let isBarrier = 1;
let isBranch = 1;
let hasSideEffects = 0;
let mayStore = 0;
let mayLoad = 0;
let isAsmParserOnly = 1;
let hasNoSchedulingInfo = 1;
}

// This will be expanded into either:
// QC.BXXX(4 bytes) + JAL(4 bytes)
// or
// QC.E.BXXX(6 bytes) + JAL(4 bytes)
def PseudoLongQC_BEQI : LongBcciPseudo<simm5nonzero, 8>;
def PseudoLongQC_BNEI : LongBcciPseudo<simm5nonzero, 8>;
def PseudoLongQC_BLTI : LongBcciPseudo<simm5nonzero, 8>;
def PseudoLongQC_BGEI : LongBcciPseudo<simm5nonzero, 8>;
def PseudoLongQC_BLTUI : LongBcciPseudo<uimm5nonzero, 8>;
def PseudoLongQC_BGEUI : LongBcciPseudo<uimm5nonzero, 8>;
def PseudoLongQC_E_BEQI : LongBcciPseudo<simm16nonzero, 10>;
def PseudoLongQC_E_BNEI : LongBcciPseudo<simm16nonzero, 10>;
def PseudoLongQC_E_BLTI : LongBcciPseudo<simm16nonzero, 10>;
def PseudoLongQC_E_BGEI : LongBcciPseudo<simm16nonzero, 10>;
def PseudoLongQC_E_BLTUI : LongBcciPseudo<uimm16nonzero, 10>;
def PseudoLongQC_E_BGEUI : LongBcciPseudo<uimm16nonzero, 10>;

//===----------------------------------------------------------------------===//
// Code Gen Patterns
Expand Down
134 changes: 134 additions & 0 deletions llvm/test/MC/RISCV/xqcibi-long-conditional-jump.s
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Original file line number Diff line number Diff line change
@@ -0,0 +1,134 @@
# RUN: llvm-mc -filetype=obj --mattr=+experimental-xqcibi -triple=riscv32 %s \
# RUN: | llvm-objdump --mattr=+experimental-xqcibi -d -M no-aliases - \
# RUN: | FileCheck --check-prefix=CHECK-INST %s
# RUN: llvm-mc -filetype=obj -triple=riscv32 -mattr=+relax,+experimental-xqcibi %s \
# RUN: | llvm-objdump --mattr=+experimental-xqcibi -dr -M no-aliases - \
# RUN: | FileCheck --check-prefix=CHECK-INST-RELAX %s

.text
.type test,@function

test:

# CHECK-INST: qc.beqi a0, 0xa, 0x8
# CHECK-INST-NEXT: jal zero, 0x1458
# CHECK-INST-RELAX: qc.beqi a0, 0xa, 0x8
# CHECK-INST-RELAX-NEXT: jal zero, {{.*}}
# CHECK-INST-RELAX-NEXT: R_RISCV_JAL .L1
qc.bnei a0, 10, .L1
.fill 1300, 4, 0
.L1:
ret

# CHECK-INST: qc.bnei a0, 0x6, 0x1462
# CHECK-INST-NEXT: jal zero, 0x28b2
# CHECK-INST-RELAX: qc.bnei a0, 0x6, 0x1462
# CHECK-INST-RELAX-NEXT: jal zero, {{.*}}
# CHECK-INST-RELAX-NEXT: R_RISCV_JAL .L2
qc.beqi a0, 6, .L2
.fill 1300, 4, 0
.L2:
ret

# CHECK-INST: qc.bgei a0, 0xd, 0x28bc
# CHECK-INST-NEXT: jal zero, 0x3d0c
# CHECK-INST-RELAX: qc.bgei a0, 0xd, 0x28bc
# CHECK-INST-RELAX-NEXT: jal zero, {{.*}}
# CHECK-INST-RELAX-NEXT: R_RISCV_JAL .L3
qc.blti a0, 13, .L3
.fill 1300, 4, 0
.L3:
ret

# CHECK-INST: qc.blti a0, 0x1, 0x3d16
# CHECK-INST-NEXT: jal zero, 0x5166
# CHECK-INST-RELAX: qc.blti a0, 0x1, 0x3d16
# CHECK-INST-RELAX-NEXT: jal zero, {{.*}}
# CHECK-INST-RELAX-NEXT: R_RISCV_JAL .L4
qc.bgei a0, 1, .L4
.fill 1300, 4, 0
.L4:
ret

# CHECK-INST: qc.bgeui a0, 0x5, 0x5170
# CHECK-INST-NEXT: jal zero, 0x65c0
# CHECK-INST-RELAX: qc.bgeui a0, 0x5, 0x5170
# CHECK-INST-RELAX-NEXT: jal zero, {{.*}}
# CHECK-INST-RELAX-NEXT: R_RISCV_JAL .L5
qc.bltui a0, 5, .L5
.fill 1300, 4, 0
.L5:
ret

# CHECK-INST: qc.bltui a0, 0xc, 0x65ca
# CHECK-INST-NEXT: jal zero, 0x7a1a
# CHECK-INST-RELAX: qc.bltui a0, 0xc, 0x65ca
# CHECK-INST-RELAX-NEXT: jal zero, {{.*}}
# CHECK-INST-RELAX-NEXT: R_RISCV_JAL .L6
qc.bgeui a0, 12, .L6
.fill 1300, 4, 0
.L6:
ret

# CHECK-INST: qc.e.beqi a0, 0x1, 0x7a26
# CHECK-INST-NEXT: jal zero, 0x8e76
# CHECK-INST-RELAX: qc.e.beqi a0, 0x1, 0x7a26
# CHECK-INST-RELAX-NEXT: jal zero, {{.*}}
# CHECK-INST-RELAX-NEXT: R_RISCV_JAL .L7
qc.e.bnei a0, 1, .L7
.fill 1300, 4, 0
.L7:
ret

# CHECK-INST: qc.e.bnei a0, 0x2, 0x8e82
# CHECK-INST-NEXT: jal zero, 0xa2d2
# CHECK-INST-RELAX: qc.e.bnei a0, 0x2, 0x8e82
# CHECK-INST-RELAX-NEXT: jal zero, {{.*}}
# CHECK-INST-RELAX-NEXT: R_RISCV_JAL .L8
qc.e.beqi a0, 2, .L8
.fill 1300, 4, 0
.L8:
ret

# CHECK-INST: qc.e.bgei a0, 0x3, 0xa2de
# CHECK-INST-NEXT: jal zero, 0xb72e
# CHECK-INST-RELAX: qc.e.bgei a0, 0x3, 0xa2de
# CHECK-INST-RELAX-NEXT: jal zero, {{.*}}
# CHECK-INST-RELAX-NEXT: R_RISCV_JAL .L9
qc.e.blti a0, 3, .L9
.fill 1300, 4, 0
.L9:
ret

# CHECK-INST: qc.e.blti a0, 0x4, 0xb73a
# CHECK-INST-NEXT: jal zero, 0xcb8a
# CHECK-INST-RELAX: qc.e.blti a0, 0x4, 0xb73a
# CHECK-INST-RELAX-NEXT: jal zero, {{.*}}
# CHECK-INST-RELAX-NEXT: R_RISCV_JAL .L10
qc.e.bgei a0, 4, .L10
.fill 1300, 4, 0
.L10:
ret

# CHECK-INST: qc.e.bgeui a0, 0x5, 0xcb96
# CHECK-INST-NEXT: jal zero, 0xdfe6
# CHECK-INST-RELAX: qc.e.bgeui a0, 0x5, 0xcb96
# CHECK-INST-RELAX-NEXT: jal zero, {{.*}}
# CHECK-INST-RELAX-NEXT: R_RISCV_JAL .L11
qc.e.bltui a0, 5, .L11
.fill 1300, 4, 0
.L11:
ret

# CHECK-INST: qc.e.bltui a0, 0x6, 0xdff2
# CHECK-INST-NEXT: jal zero, 0xf442
# CHECK-INST-RELAX: qc.e.bltui a0, 0x6, 0xdff2
# CHECK-INST-RELAX-NEXT: jal zero, {{.*}}
# CHECK-INST-RELAX-NEXT: R_RISCV_JAL .L12
qc.e.bgeui a0, 6, .L12
.fill 1300, 4, 0
.L12:
ret

.Lfunc_end0:
.size test, .Lfunc_end0-test
15 changes: 7 additions & 8 deletions llvm/test/MC/RISCV/xqcibi-relocations.s
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Original file line number Diff line number Diff line change
Expand Up @@ -10,23 +10,22 @@

.text

# Check that branch to an undefined symbol is handled
# FIXME: This should be relaxed to an inverse branch and jump
# Since foo is undefined, this will be relaxed to (qc.beqi + jal)
qc.bnei x6, 10, foo
# RELOC: R_RISCV_BRANCH foo 0x0
# RELOC: R_RISCV_JAL foo 0x0
# INSTR: qc.bnei t1, 10, foo
# FIXUP: fixup A - offset: 0, value: foo, kind: fixup_riscv_branch

# FIXME: This should be relaxed to an inverse branch and jump
# Since foo is undefined, this will be relaxed to (qc.e.bltui + jal)
qc.e.bgeui x8, 12, foo
# RELOC: R_RISCV_CUSTOM193 foo 0x0
# RELOC: R_RISCV_JAL foo 0x0
# INSTR: qc.e.bgeui s0, 12, foo
# FIXUP: fixup A - offset: 0, value: foo, kind: fixup_riscv_qc_e_branch

# Check that a label in a different section is handled similar to an undefined symbol
# FIXME: This should be relaxed to an inverse branch and jump
# Check that a label in a different section is handled similar to an undefined
# symbol and gets relaxed to (qc.e.bgeui + jal)
qc.e.bltui x4, 9, .bar
# RELOC: R_RISCV_CUSTOM193 .bar 0x0
# RELOC: R_RISCV_JAL .bar 0x0
# INSTR: qc.e.bltui tp, 9, .bar
# FIXUP: fixup A - offset: 0, value: .bar, kind: fixup_riscv_qc_e_branch

Expand Down