[llvm] [RISCV][GISEL] Legalize G_VASTART using custom legalization (PR #73063)
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Tue Nov 21 17:37:25 PST 2023
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-globalisel
@llvm/pr-subscribers-backend-risc-v
Author: Michael Maitland (michaelmaitland)
<details>
<summary>Changes</summary>
---
Full diff: https://github.com/llvm/llvm-project/pull/73063.diff
2 Files Affected:
- (modified) llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.cpp (+24)
- (modified) llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.h (+3)
``````````diff
diff --git a/llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.cpp b/llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.cpp
index 9eb5812e024b915..bb518ed6663d382 100644
--- a/llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.cpp
+++ b/llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.cpp
@@ -11,6 +11,7 @@
//===----------------------------------------------------------------------===//
#include "RISCVLegalizerInfo.h"
+#include "RISCVMachineFunctionInfo.h"
#include "RISCVSubtarget.h"
#include "llvm/CodeGen/GlobalISel/LegalizerHelper.h"
#include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
@@ -261,6 +262,8 @@ RISCVLegalizerInfo::RISCVLegalizerInfo(const RISCVSubtarget &ST) {
getActionDefinitionsBuilder({G_FCEIL, G_FFLOOR})
.libcallFor({s32, s64});
+ getActionDefinitionsBuilder(G_VASTART).customFor({p0});
+
getLegacyLegalizerInfo().computeTables();
}
@@ -288,6 +291,25 @@ bool RISCVLegalizerInfo::legalizeShlAshrLshr(
return true;
}
+bool RISCVLegalizerInfo::legalizeVAStart(MachineInstr &MI,
+ MachineIRBuilder &MIRBuilder,
+ GISelChangeObserver &Observer) const {
+ // Stores the address of the VarArgsFrameIndex slot into the memory location
+ assert(MI.getOpcode() == TargetOpcode::G_VASTART);
+ MachineFunction *MF = MI.getParent()->getParent();
+ RISCVMachineFunctionInfo *FuncInfo = MF->getInfo<RISCVMachineFunctionInfo>();
+ int FI = FuncInfo->getVarArgsFrameIndex();
+ LLT AddrTy = MIRBuilder.getMRI()->getType(MI.getOperand(0).getReg());
+ auto FINAddr = MIRBuilder.buildFrameIndex(AddrTy, FI);
+ assert(MI.hasOneMemOperand());
+ MachineInstr *LoweredMI = MIRBuilder.buildStore(
+ MI.getOperand(0).getReg(), FINAddr, *MI.memoperands()[0]);
+ Observer.createdInstr(*LoweredMI);
+ Observer.erasingInstr(MI);
+ MI.eraseFromParent();
+ return true;
+}
+
bool RISCVLegalizerInfo::legalizeCustom(LegalizerHelper &Helper,
MachineInstr &MI) const {
MachineIRBuilder &MIRBuilder = Helper.MIRBuilder;
@@ -309,6 +331,8 @@ bool RISCVLegalizerInfo::legalizeCustom(LegalizerHelper &Helper,
return Helper.lower(MI, 0, /* Unused hint type */ LLT()) ==
LegalizerHelper::Legalized;
}
+ case TargetOpcode::G_VASTART:
+ return legalizeVAStart(MI, MIRBuilder, Observer);
}
llvm_unreachable("expected switch to return");
diff --git a/llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.h b/llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.h
index f39d3a130d85063..9da7c1e42afc649 100644
--- a/llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.h
+++ b/llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.h
@@ -31,6 +31,9 @@ class RISCVLegalizerInfo : public LegalizerInfo {
private:
bool legalizeShlAshrLshr(MachineInstr &MI, MachineIRBuilder &MIRBuilder,
GISelChangeObserver &Observer) const;
+
+ bool legalizeVAStart(MachineInstr &MI, MachineIRBuilder &MIRBuilder,
+ GISelChangeObserver &Observer) const;
};
} // end namespace llvm
#endif
``````````
</details>
https://github.com/llvm/llvm-project/pull/73063
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