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[RISCV] Add early-exit to RVV stack computation. NFCI. 

This patch was split off from D126465, where an early-exit is necessary
as it checks the VLEN and that asserts that V instructions are present.

Since this makes logical sense on its own, I think it's worth landing
regardless of D126465.

Reviewed By: kito-cheng

Differential Revision: https://reviews.llvm.org/D129617
This commit is contained in:
Fraser Cormack 2022-07-13 06:41:27 +01:00
parent 491d27013d
commit b336cf856e
2 changed files with 15 additions and 6 deletions
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17
llvm/lib/Target/RISCV/RISCVFrameLowering.cpp
View File

@ -899,7 +899,8 @@ void RISCVFrameLowering::determineCalleeSaves(MachineFunction &MF,
} }
std::pair<int64_t, Align> std::pair<int64_t, Align>
RISCVFrameLowering::assignRVVStackObjectOffsets(MachineFrameInfo &MFI) const { RISCVFrameLowering::assignRVVStackObjectOffsets(MachineFunction &MF) const {
MachineFrameInfo &MFI = MF.getFrameInfo();
// Create a buffer of RVV objects to allocate. // Create a buffer of RVV objects to allocate.
SmallVector<int, 8> ObjectsToAllocate; SmallVector<int, 8> ObjectsToAllocate;
for (int I = 0, E = MFI.getObjectIndexEnd(); I != E; ++I) { for (int I = 0, E = MFI.getObjectIndexEnd(); I != E; ++I) {
@ -912,10 +913,18 @@ RISCVFrameLowering::assignRVVStackObjectOffsets(MachineFrameInfo &MFI) const {
ObjectsToAllocate.push_back(I); ObjectsToAllocate.push_back(I);
} }
// Allocate all RVV locals and spills
int64_t Offset = 0;
// The minimum alignment is 16 bytes. // The minimum alignment is 16 bytes.
Align RVVStackAlign(16); Align RVVStackAlign(16);
const auto &ST = MF.getSubtarget<RISCVSubtarget>();
if (!ST.hasVInstructions()) {
assert(ObjectsToAllocate.empty() &&
"Can't allocate scalable-vector objects without V instructions");
return std::make_pair(0, RVVStackAlign);
}
// Allocate all RVV locals and spills
int64_t Offset = 0;
for (int FI : ObjectsToAllocate) { for (int FI : ObjectsToAllocate) {
// ObjectSize in bytes. // ObjectSize in bytes.
int64_t ObjectSize = MFI.getObjectSize(FI); int64_t ObjectSize = MFI.getObjectSize(FI);
@ -997,7 +1006,7 @@ void RISCVFrameLowering::processFunctionBeforeFrameFinalized(
int64_t RVVStackSize; int64_t RVVStackSize;
Align RVVStackAlign; Align RVVStackAlign;
std::tie(RVVStackSize, RVVStackAlign) = assignRVVStackObjectOffsets(MFI); std::tie(RVVStackSize, RVVStackAlign) = assignRVVStackObjectOffsets(MF);
RVFI->setRVVStackSize(RVVStackSize); RVFI->setRVVStackSize(RVVStackSize);
RVFI->setRVVStackAlign(RVVStackAlign); RVFI->setRVVStackAlign(RVVStackAlign);

4
llvm/lib/Target/RISCV/RISCVFrameLowering.h
View File

@ -84,7 +84,7 @@ private:
MachineBasicBlock::iterator MBBI, const DebugLoc &DL, MachineBasicBlock::iterator MBBI, const DebugLoc &DL,
int64_t Amount, MachineInstr::MIFlag Flag) const; int64_t Amount, MachineInstr::MIFlag Flag) const;
std::pair<int64_t, Align> std::pair<int64_t, Align>
assignRVVStackObjectOffsets(MachineFrameInfo &MFI) const; assignRVVStackObjectOffsets(MachineFunction &MF) const;
}; };
} } // namespace llvm
#endif #endif