[llvm] [RISCV] Add new CondCode COND_CV_BEQIMM/COND_CV_BNEIMM for CV immediate branch (PR #135771)
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Tue Apr 15 03:07:18 PDT 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-backend-risc-v
Author: Jim Lin (tclin914)
<details>
<summary>Changes</summary>
If there is another branch instruction also with immediate operand, but it is used to specify which bit to be tested is set or clear. We only check whether operand2 is immediate or not here. There are no way to distinguish between them.
So add new CondCode COND_CV_BEQIMM/COND_CV_BNEIMM that we can know what kinds of immediate branch instruction are matched in Select_* Pseudo.
---
Full diff: https://github.com/llvm/llvm-project/pull/135771.diff
5 Files Affected:
- (modified) llvm/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp (+1-1)
- (modified) llvm/lib/Target/RISCV/RISCVISelLowering.cpp (+1-1)
- (modified) llvm/lib/Target/RISCV/RISCVInstrInfo.cpp (+18-20)
- (modified) llvm/lib/Target/RISCV/RISCVInstrInfo.h (+4-2)
- (modified) llvm/lib/Target/RISCV/RISCVInstrInfoXCV.td (+8-1)
``````````diff
diff --git a/llvm/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp b/llvm/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp
index 18ce5407f816c..f83c2b6da8923 100644
--- a/llvm/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp
+++ b/llvm/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp
@@ -789,7 +789,7 @@ bool RISCVInstructionSelector::select(MachineInstr &MI) {
RISCVCC::CondCode CC;
getOperandsForBranch(MI.getOperand(0).getReg(), CC, LHS, RHS, *MRI);
- auto Bcc = MIB.buildInstr(RISCVCC::getBrCond(STI, CC), {}, {LHS, RHS})
+ auto Bcc = MIB.buildInstr(RISCVCC::getBrCond(CC), {}, {LHS, RHS})
.addMBB(MI.getOperand(1).getMBB());
MI.eraseFromParent();
return constrainSelectedInstRegOperands(*Bcc, TII, TRI, RBI);
diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index e5843477e04e5..33112d36dab43 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -20640,7 +20640,7 @@ static MachineBasicBlock *emitSelectPseudo(MachineInstr &MI,
// Insert appropriate branch.
if (MI.getOperand(2).isImm())
- BuildMI(HeadMBB, DL, TII.getBrCond(CC, MI.getOperand(2).isImm()))
+ BuildMI(HeadMBB, DL, TII.getBrCond(CC))
.addReg(LHS)
.addImm(MI.getOperand(2).getImm())
.addMBB(TailMBB);
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
index f8a35533ba952..68dd99bb743bf 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
@@ -974,10 +974,6 @@ static RISCVCC::CondCode getCondFromBranchOpc(unsigned Opc) {
switch (Opc) {
default:
return RISCVCC::COND_INVALID;
- case RISCV::CV_BEQIMM:
- return RISCVCC::COND_EQ;
- case RISCV::CV_BNEIMM:
- return RISCVCC::COND_NE;
case RISCV::BEQ:
return RISCVCC::COND_EQ;
case RISCV::BNE:
@@ -990,6 +986,10 @@ static RISCVCC::CondCode getCondFromBranchOpc(unsigned Opc) {
return RISCVCC::COND_LTU;
case RISCV::BGEU:
return RISCVCC::COND_GEU;
+ case RISCV::CV_BEQIMM:
+ return RISCVCC::COND_CV_BEQIMM;
+ case RISCV::CV_BNEIMM:
+ return RISCVCC::COND_CV_BNEIMM;
}
}
@@ -1027,23 +1027,14 @@ static void parseCondBranch(MachineInstr &LastInst, MachineBasicBlock *&Target,
Cond.push_back(LastInst.getOperand(1));
}
-unsigned RISCVCC::getBrCond(const RISCVSubtarget &STI, RISCVCC::CondCode CC,
- bool Imm) {
+unsigned RISCVCC::getBrCond(RISCVCC::CondCode CC) {
switch (CC) {
default:
llvm_unreachable("Unknown condition code!");
case RISCVCC::COND_EQ:
- if (!Imm)
- return RISCV::BEQ;
- if (STI.hasVendorXCVbi())
- return RISCV::CV_BEQIMM;
- llvm_unreachable("Unknown branch immediate!");
+ return RISCV::BEQ;
case RISCVCC::COND_NE:
- if (!Imm)
- return RISCV::BNE;
- if (STI.hasVendorXCVbi())
- return RISCV::CV_BNEIMM;
- llvm_unreachable("Unknown branch immediate!");
+ return RISCV::BNE;
case RISCVCC::COND_LT:
return RISCV::BLT;
case RISCVCC::COND_GE:
@@ -1052,12 +1043,15 @@ unsigned RISCVCC::getBrCond(const RISCVSubtarget &STI, RISCVCC::CondCode CC,
return RISCV::BLTU;
case RISCVCC::COND_GEU:
return RISCV::BGEU;
+ case RISCVCC::COND_CV_BEQIMM:
+ return RISCV::CV_BEQIMM;
+ case RISCVCC::COND_CV_BNEIMM:
+ return RISCV::CV_BNEIMM;
}
}
-const MCInstrDesc &RISCVInstrInfo::getBrCond(RISCVCC::CondCode CC,
- bool Imm) const {
- return get(RISCVCC::getBrCond(STI, CC, Imm));
+const MCInstrDesc &RISCVInstrInfo::getBrCond(RISCVCC::CondCode CC) const {
+ return get(RISCVCC::getBrCond(CC));
}
RISCVCC::CondCode RISCVCC::getOppositeBranchCondition(RISCVCC::CondCode CC) {
@@ -1076,6 +1070,10 @@ RISCVCC::CondCode RISCVCC::getOppositeBranchCondition(RISCVCC::CondCode CC) {
return RISCVCC::COND_GEU;
case RISCVCC::COND_GEU:
return RISCVCC::COND_LTU;
+ case RISCVCC::COND_CV_BEQIMM:
+ return RISCVCC::COND_CV_BNEIMM;
+ case RISCVCC::COND_CV_BNEIMM:
+ return RISCVCC::COND_CV_BEQIMM;
}
}
@@ -1206,7 +1204,7 @@ unsigned RISCVInstrInfo::insertBranch(
// Either a one or two-way conditional branch.
auto CC = static_cast<RISCVCC::CondCode>(Cond[0].getImm());
- MachineInstr &CondMI = *BuildMI(&MBB, DL, getBrCond(CC, Cond[2].isImm()))
+ MachineInstr &CondMI = *BuildMI(&MBB, DL, getBrCond(CC))
.add(Cond[1])
.add(Cond[2])
.addMBB(TBB);
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfo.h b/llvm/lib/Target/RISCV/RISCVInstrInfo.h
index bf0d6b2c59a45..67e457d64f6e3 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfo.h
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfo.h
@@ -41,11 +41,13 @@ enum CondCode {
COND_GE,
COND_LTU,
COND_GEU,
+ COND_CV_BEQIMM,
+ COND_CV_BNEIMM,
COND_INVALID
};
CondCode getOppositeBranchCondition(CondCode);
-unsigned getBrCond(const RISCVSubtarget &STI, CondCode CC, bool Imm = false);
+unsigned getBrCond(CondCode CC);
} // end of namespace RISCVCC
@@ -65,7 +67,7 @@ class RISCVInstrInfo : public RISCVGenInstrInfo {
explicit RISCVInstrInfo(RISCVSubtarget &STI);
MCInst getNop() const override;
- const MCInstrDesc &getBrCond(RISCVCC::CondCode CC, bool Imm = false) const;
+ const MCInstrDesc &getBrCond(RISCVCC::CondCode CC) const;
Register isLoadFromStackSlot(const MachineInstr &MI,
int &FrameIndex) const override;
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfoXCV.td b/llvm/lib/Target/RISCV/RISCVInstrInfoXCV.td
index b5df7b54fc9f1..5ce08d64b141d 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfoXCV.td
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfoXCV.td
@@ -791,6 +791,13 @@ let Predicates = [HasVendorXCValu, IsRV32], AddedComplexity = 1 in {
// Patterns for immediate branching operations
//===----------------------------------------------------------------------===//
+def IntCCtoRISCVCCCV : SDNodeXForm<riscv_selectcc, [{
+ ISD::CondCode CC = cast<CondCodeSDNode>(N->getOperand(2))->get();
+ assert(CC == ISD::SETEQ || CC == ISD::SETNE);
+ RISCVCC::CondCode BrCC = CC == ISD::SETEQ ? RISCVCC::COND_CV_BEQIMM : RISCVCC::COND_CV_BNEIMM;
+ return CurDAG->getTargetConstant(BrCC, SDLoc(N), Subtarget->getXLenVT());
+}]>;
+
let Predicates = [HasVendorXCVbi, IsRV32], AddedComplexity = 2 in {
def : Pat<(riscv_brcc GPR:$rs1, simm5:$imm5, SETEQ, bb:$imm12),
(CV_BEQIMM GPR:$rs1, simm5:$imm5, bare_simm13_lsb0:$imm12)>;
@@ -807,7 +814,7 @@ let Predicates = [HasVendorXCVbi, IsRV32], AddedComplexity = 2 in {
: Pat<(riscv_selectcc_frag:$cc (i32 GPR:$lhs), simm5:$Constant, Cond,
(i32 GPR:$truev), GPR:$falsev),
(Select_GPR_Using_CC_Imm GPR:$lhs, simm5:$Constant,
- (IntCCtoRISCVCC $cc), GPR:$truev, GPR:$falsev)>;
+ (IntCCtoRISCVCCCV $cc), GPR:$truev, GPR:$falsev)>;
def : Selectbi<SETEQ>;
def : Selectbi<SETNE>;
``````````
</details>
https://github.com/llvm/llvm-project/pull/135771
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