[llvm] [RISCV][GISel] Select G_SELECT (PR #67614)
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Wed Sep 27 15:20:02 PDT 2023
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-backend-risc-v
<details>
<summary>Changes</summary>
This patch adds minimal support for selecting G_SELECT. In the future we may want to fix this patch to select the other opcodes or handle that in the combiner.
---
Full diff: https://github.com/llvm/llvm-project/pull/67614.diff
3 Files Affected:
- (modified) llvm/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp (+27)
- (added) llvm/test/CodeGen/RISCV/GlobalISel/instruction-select/select-rv32.mir (+55)
- (added) llvm/test/CodeGen/RISCV/GlobalISel/instruction-select/select-rv64.mir (+55)
``````````diff
diff --git a/llvm/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp b/llvm/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp
index 2e690a3624edcb3..c5f3fdacce07927 100644
--- a/llvm/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp
+++ b/llvm/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp
@@ -44,11 +44,17 @@ class RISCVInstructionSelector : public InstructionSelector {
const TargetRegisterClass *
getRegClassForTypeOnBank(LLT Ty, const RegisterBank &RB) const;
+ // tblgen-erated 'select' implementation, used as the initial selector for
+ // the patterns that don't require complex C++.
bool selectImpl(MachineInstr &I, CodeGenCoverage &CoverageInfo) const;
+
+ // Custom selection methods
bool selectCopy(MachineInstr &MI, MachineRegisterInfo &MRI) const;
bool selectConstant(MachineInstr &MI, MachineIRBuilder &MIB,
MachineRegisterInfo &MRI) const;
bool selectSExtInreg(MachineInstr &MI, MachineIRBuilder &MIB) const;
+ bool selectSelect(MachineInstr &MI, MachineIRBuilder &MIB,
+ MachineRegisterInfo &MRI) const;
bool earlySelectShift(unsigned Opc, MachineInstr &I, MachineIRBuilder &MIB,
const MachineRegisterInfo &MRI);
@@ -240,6 +246,11 @@ bool RISCVInstructionSelector::select(MachineInstr &MI) {
}
case TargetOpcode::G_SEXT_INREG:
return selectSExtInreg(MI, MIB);
+ case TargetOpcode::G_SELECT:
+ if (!selectSelect(MI, MIB, MRI))
+ return false;
+ MI.eraseFromParent();
+ return true;
default:
return false;
}
@@ -389,6 +400,22 @@ bool RISCVInstructionSelector::selectSExtInreg(MachineInstr &MI,
return true;
}
+bool RISCVInstructionSelector::selectSelect(MachineInstr &MI,
+ MachineIRBuilder &MIB,
+ MachineRegisterInfo &MRI) const {
+ // TODO: We need to either fix this to use other opcodes or handle it in the
+ // combiner.
+ assert(MI.getOpcode() == TargetOpcode::G_SELECT);
+ MachineInstr *Result = MIB.buildInstr(RISCV::Select_GPR_Using_CC_GPR)
+ .addDef(MI.getOperand(0).getReg())
+ .addReg(MI.getOperand(1).getReg())
+ .addReg(RISCV::X0)
+ .addImm(RISCVCC::COND_NE)
+ .addReg(MI.getOperand(2).getReg())
+ .addReg(MI.getOperand(3).getReg());
+ return constrainSelectedInstRegOperands(*Result, TII, TRI, RBI);
+}
+
namespace llvm {
InstructionSelector *
createRISCVInstructionSelector(const RISCVTargetMachine &TM,
diff --git a/llvm/test/CodeGen/RISCV/GlobalISel/instruction-select/select-rv32.mir b/llvm/test/CodeGen/RISCV/GlobalISel/instruction-select/select-rv32.mir
new file mode 100644
index 000000000000000..828835dac8f80ca
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/GlobalISel/instruction-select/select-rv32.mir
@@ -0,0 +1,55 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=riscv32 -run-pass=instruction-select --simplify-mir \
+# RUN: -verify-machineinstrs %s -o - | FileCheck %s
+---
+name: select_s32
+legalized: true
+regBankSelected: true
+tracksRegLiveness: true
+body: |
+ bb.0:
+ liveins: $x10, $x11, $x12
+
+ ; CHECK-LABEL: name: select_s32
+ ; CHECK: liveins: $x10, $x11, $x12
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: [[COPY:%[0-9]+]]:gpr = COPY $x10
+ ; CHECK-NEXT: [[COPY1:%[0-9]+]]:gpr = COPY $x11
+ ; CHECK-NEXT: [[COPY2:%[0-9]+]]:gpr = COPY $x12
+ ; CHECK-NEXT: [[Select_GPR_Using_CC_GPR:%[0-9]+]]:gpr = Select_GPR_Using_CC_GPR [[COPY]], $x0, 1, [[COPY1]], [[COPY2]]
+ ; CHECK-NEXT: $x10 = COPY [[Select_GPR_Using_CC_GPR]]
+ ; CHECK-NEXT: PseudoRET implicit $x10
+ %0:gprb(s32) = COPY $x10
+ %1:gprb(s32) = COPY $x11
+ %2:gprb(s32) = COPY $x12
+ %3:gprb(s32) = G_SELECT %0, %1, %2
+ $x10 = COPY %3(s32)
+ PseudoRET implicit $x10
+
+...
+---
+name: select_p0
+legalized: true
+regBankSelected: true
+tracksRegLiveness: true
+body: |
+ bb.0:
+ liveins: $x10, $x11, $x12
+
+ ; CHECK-LABEL: name: select_p0
+ ; CHECK: liveins: $x10, $x11, $x12
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: [[COPY:%[0-9]+]]:gpr = COPY $x10
+ ; CHECK-NEXT: [[COPY1:%[0-9]+]]:gpr = COPY $x11
+ ; CHECK-NEXT: [[COPY2:%[0-9]+]]:gpr = COPY $x12
+ ; CHECK-NEXT: [[Select_GPR_Using_CC_GPR:%[0-9]+]]:gpr = Select_GPR_Using_CC_GPR [[COPY]], $x0, 1, [[COPY1]], [[COPY2]]
+ ; CHECK-NEXT: $x10 = COPY [[Select_GPR_Using_CC_GPR]]
+ ; CHECK-NEXT: PseudoRET implicit $x10
+ %0:gprb(s32) = COPY $x10
+ %1:gprb(p0) = COPY $x11
+ %2:gprb(p0) = COPY $x12
+ %3:gprb(p0) = G_SELECT %0, %1, %2
+ $x10 = COPY %3(p0)
+ PseudoRET implicit $x10
+
+...
diff --git a/llvm/test/CodeGen/RISCV/GlobalISel/instruction-select/select-rv64.mir b/llvm/test/CodeGen/RISCV/GlobalISel/instruction-select/select-rv64.mir
new file mode 100644
index 000000000000000..caa42f01c40cad1
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/GlobalISel/instruction-select/select-rv64.mir
@@ -0,0 +1,55 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=riscv64 -run-pass=instruction-select %s -o - \
+# RUN: | FileCheck %s
+---
+name: select_s64
+legalized: true
+regBankSelected: true
+tracksRegLiveness: true
+body: |
+ bb.0:
+ liveins: $x10, $x11, $x12
+
+ ; CHECK-LABEL: name: select_s64
+ ; CHECK: liveins: $x10, $x11, $x12
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: [[COPY:%[0-9]+]]:gpr = COPY $x10
+ ; CHECK-NEXT: [[COPY1:%[0-9]+]]:gpr = COPY $x11
+ ; CHECK-NEXT: [[COPY2:%[0-9]+]]:gpr = COPY $x12
+ ; CHECK-NEXT: [[Select_GPR_Using_CC_GPR:%[0-9]+]]:gpr = Select_GPR_Using_CC_GPR [[COPY]], $x0, 1, [[COPY1]], [[COPY2]]
+ ; CHECK-NEXT: $x10 = COPY [[Select_GPR_Using_CC_GPR]]
+ ; CHECK-NEXT: PseudoRET implicit $x10
+ %0:gprb(s64) = COPY $x10
+ %1:gprb(s64) = COPY $x11
+ %2:gprb(s64) = COPY $x12
+ %3:gprb(s64) = G_SELECT %0, %1, %2
+ $x10 = COPY %3(s64)
+ PseudoRET implicit $x10
+
+...
+---
+name: select_p0
+legalized: true
+regBankSelected: true
+tracksRegLiveness: true
+body: |
+ bb.0:
+ liveins: $x10, $x11, $x12
+
+ ; CHECK-LABEL: name: select_p0
+ ; CHECK: liveins: $x10, $x11, $x12
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: [[COPY:%[0-9]+]]:gpr = COPY $x10
+ ; CHECK-NEXT: [[COPY1:%[0-9]+]]:gpr = COPY $x11
+ ; CHECK-NEXT: [[COPY2:%[0-9]+]]:gpr = COPY $x12
+ ; CHECK-NEXT: [[Select_GPR_Using_CC_GPR:%[0-9]+]]:gpr = Select_GPR_Using_CC_GPR [[COPY]], $x0, 1, [[COPY1]], [[COPY2]]
+ ; CHECK-NEXT: $x10 = COPY [[Select_GPR_Using_CC_GPR]]
+ ; CHECK-NEXT: PseudoRET implicit $x10
+ %0:gprb(s64) = COPY $x10
+ %1:gprb(p0) = COPY $x11
+ %2:gprb(p0) = COPY $x12
+ %3:gprb(p0) = G_SELECT %0, %1, %2
+ $x10 = COPY %3(p0)
+ PseudoRET implicit $x10
+
+...
``````````
</details>
https://github.com/llvm/llvm-project/pull/67614
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