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[RISCV] Limit VLEN in getOptimalMemOpType to prevent creating invalid MVTs. #139116

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Merged
merged 3 commits into from
May 8, 2025
Merged

[RISCV] Limit VLEN in getOptimalMemOpType to prevent creating invalid MVTs. #139116

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d3b19ae
[RISCV] Limit VLEN in getOptimalMemOpType to prevent creating invalid…
topperc May 8, 2025
dfb9d83
fixup! clang-format/
topperc May 8, 2025
ea26287
fixup! test case
topperc May 8, 2025
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5 changes: 4 additions & 1 deletion llvm/lib/Target/RISCV/RISCVISelLowering.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -23487,7 +23487,10 @@ EVT RISCVTargetLowering::getOptimalMemOpType(const MemOp &Op,
// combining will typically form larger LMUL operations from the LMUL1
// operations emitted here, and that's okay because combining isn't
// introducing new memory operations; it's just merging existing ones.
const unsigned MinVLenInBytes = Subtarget.getRealMinVLen()/8;
// NOTE: We limit to 1024 bytes to avoid creating an invalid MVT.
const unsigned MinVLenInBytes =
std::min(Subtarget.getRealMinVLen() / 8, 1024U);

if (Op.size() < MinVLenInBytes)
// TODO: Figure out short memops. For the moment, do the default thing
// which ends up using scalar sequences.
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18 changes: 18 additions & 0 deletions llvm/test/CodeGen/RISCV/rvv/pr139075.ll
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@@ -0,0 +1,18 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
; RUN: llc < %s -mtriple=riscv64 -mattr=+v,+zvl16384b | FileCheck %s

define void @a(ptr %0, ptr %1) {
; CHECK-LABEL: a:
; CHECK: # %bb.0:
; CHECK-NEXT: li a2, 1024
; CHECK-NEXT: vsetvli zero, a2, e8, mf2, ta, ma
; CHECK-NEXT: vle8.v v8, (a1)
; CHECK-NEXT: vse8.v v8, (a0)
; CHECK-NEXT: addi a1, a1, 1024
; CHECK-NEXT: vle8.v v8, (a1)
; CHECK-NEXT: addi a0, a0, 1024
; CHECK-NEXT: vse8.v v8, (a0)
; CHECK-NEXT: ret
call void @llvm.memcpy.p0.p0.i64(ptr align 1 %0, ptr align 4 %1, i64 2048, i1 false)
ret void
}
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