[llvm] [RISCV] Handle non uimm5 VL constants in isVLKnownLE (PR #156639)
Luke Lau via llvm-commits
llvm-commits at lists.llvm.org
Wed Sep 3 21:15:13 PDT 2025
https://github.com/lukel97 updated https://github.com/llvm/llvm-project/pull/156639
>From b0ac49344b251a1ba70fcd4863e85aab20eef6cf Mon Sep 17 00:00:00 2001
From: Luke Lau <luke at igalia.com>
Date: Wed, 3 Sep 2025 18:06:28 +0800
Subject: [PATCH 1/4] Precommit tests
---
llvm/test/CodeGen/RISCV/rvv/vmv.v.v-peephole.ll | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/llvm/test/CodeGen/RISCV/rvv/vmv.v.v-peephole.ll b/llvm/test/CodeGen/RISCV/rvv/vmv.v.v-peephole.ll
index 2f2035b02b552..1c7b13db624d5 100644
--- a/llvm/test/CodeGen/RISCV/rvv/vmv.v.v-peephole.ll
+++ b/llvm/test/CodeGen/RISCV/rvv/vmv.v.v-peephole.ll
@@ -82,6 +82,22 @@ define <vscale x 4 x i32> @diff_avl_vlmax(<vscale x 4 x i32> %passthru, <vscale
ret <vscale x 4 x i32> %w
}
+define <vscale x 4 x i32> @diff_avl_non_uimm5(<vscale x 4 x i32> %passthru, <vscale x 4 x i32> %a, <vscale x 4 x i32> %b) {
+; CHECK-LABEL: diff_avl_non_uimm5:
+; CHECK: # %bb.0:
+; CHECK-NEXT: li a0, 42
+; CHECK-NEXT: vsetvli zero, a0, e32, m2, tu, ma
+; CHECK-NEXT: vmv2r.v v14, v8
+; CHECK-NEXT: vadd.vv v14, v10, v12
+; CHECK-NEXT: li a0, 123
+; CHECK-NEXT: vsetvli zero, a0, e32, m2, tu, ma
+; CHECK-NEXT: vmv.v.v v8, v14
+; CHECK-NEXT: ret
+ %v = call <vscale x 4 x i32> @llvm.riscv.vadd.nxv4i32.nxv4i32(<vscale x 4 x i32> %passthru, <vscale x 4 x i32> %a, <vscale x 4 x i32> %b, iXLen 42)
+ %w = call <vscale x 4 x i32> @llvm.riscv.vmv.v.v.nxv4i32(<vscale x 4 x i32> %passthru, <vscale x 4 x i32> %v, iXLen 123)
+ ret <vscale x 4 x i32> %w
+}
+
define <vscale x 4 x i32> @vadd_mask_ma(<vscale x 4 x i32> %passthru, <vscale x 4 x i32> %a, <vscale x 4 x i32> %b, <vscale x 4 x i1> %mask, iXLen %vl) {
; CHECK-LABEL: vadd_mask_ma:
; CHECK: # %bb.0:
>From 7364a519c20592dd2e0c921e1d68ded19d3e61bc Mon Sep 17 00:00:00 2001
From: Luke Lau <luke at igalia.com>
Date: Wed, 3 Sep 2025 18:19:38 +0800
Subject: [PATCH 2/4] [RISCV] Handle non uimm5 VL constants in isVLKnownLE
If a VL operand is > 31 then it will be materialized into an ADDI $x0, imm. We can reason about it by peeking at the virtual register definition which allows RISCVVectorPeephole and RISCVVLOptimizer to catch more cases.
There's a separate issue with RISCVVLOptimizer where the materialized immediate may not always dominate the instruction we want to reduce the VL of, but this is left to another patch.
---
llvm/lib/Target/RISCV/RISCVInstrInfo.cpp | 27 ++++++++++++----
llvm/lib/Target/RISCV/RISCVInstrInfo.h | 3 +-
llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp | 10 +++---
llvm/lib/Target/RISCV/RISCVVectorPeephole.cpp | 16 +++++-----
.../RISCV/rvv/fixed-vectors-vadd-vp.ll | 5 +--
.../RISCV/rvv/fixed-vectors-vmax-vp.ll | 5 +--
.../RISCV/rvv/fixed-vectors-vmaxu-vp.ll | 5 +--
.../RISCV/rvv/fixed-vectors-vmin-vp.ll | 5 +--
.../RISCV/rvv/fixed-vectors-vminu-vp.ll | 5 +--
.../RISCV/rvv/fixed-vectors-vsadd-vp.ll | 5 +--
.../RISCV/rvv/fixed-vectors-vsaddu-vp.ll | 5 +--
.../RISCV/rvv/fixed-vectors-vselect-vp.ll | 31 +++++--------------
.../RISCV/rvv/fixed-vectors-vssub-vp.ll | 11 ++++---
.../RISCV/rvv/fixed-vectors-vssubu-vp.ll | 11 ++++---
.../CodeGen/RISCV/rvv/vmv.v.v-peephole.ll | 6 +---
15 files changed, 77 insertions(+), 73 deletions(-)
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
index 7b4a1de167695..0a86406d1c14b 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
@@ -4796,20 +4796,35 @@ unsigned RISCV::getDestLog2EEW(const MCInstrDesc &Desc, unsigned Log2SEW) {
return Scaled;
}
+static std::optional<int64_t> getEffectiveImm(const MachineOperand &MO,
+ const MachineRegisterInfo *MRI) {
+ assert(MO.isImm() || MO.getReg().isVirtual());
+ if (MO.isImm())
+ return MO.getImm();
+ MachineInstr *Def = MRI->getVRegDef(MO.getReg());
+ if (Def->getOpcode() == RISCV::ADDI &&
+ Def->getOperand(1).getReg() == RISCV::X0)
+ return Def->getOperand(2).getImm();
+ return std::nullopt;
+}
+
/// Given two VL operands, do we know that LHS <= RHS?
-bool RISCV::isVLKnownLE(const MachineOperand &LHS, const MachineOperand &RHS) {
+bool RISCV::isVLKnownLE(const MachineOperand &LHS, const MachineOperand &RHS,
+ const MachineRegisterInfo *MRI) {
if (LHS.isReg() && RHS.isReg() && LHS.getReg().isVirtual() &&
LHS.getReg() == RHS.getReg())
return true;
- if (RHS.isImm() && RHS.getImm() == RISCV::VLMaxSentinel)
+ std::optional<int64_t> LHSImm = getEffectiveImm(LHS, MRI),
+ RHSImm = getEffectiveImm(RHS, MRI);
+ if (RHSImm == RISCV::VLMaxSentinel)
return true;
- if (LHS.isImm() && LHS.getImm() == 0)
+ if (LHSImm == 0)
return true;
- if (LHS.isImm() && LHS.getImm() == RISCV::VLMaxSentinel)
+ if (LHSImm == RISCV::VLMaxSentinel)
return false;
- if (!LHS.isImm() || !RHS.isImm())
+ if (!LHSImm || !RHSImm)
return false;
- return LHS.getImm() <= RHS.getImm();
+ return LHSImm <= RHSImm;
}
namespace {
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfo.h b/llvm/lib/Target/RISCV/RISCVInstrInfo.h
index 785c8352d4a5e..0defb184fba6d 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfo.h
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfo.h
@@ -365,7 +365,8 @@ unsigned getDestLog2EEW(const MCInstrDesc &Desc, unsigned Log2SEW);
static constexpr int64_t VLMaxSentinel = -1LL;
/// Given two VL operands, do we know that LHS <= RHS?
-bool isVLKnownLE(const MachineOperand &LHS, const MachineOperand &RHS);
+bool isVLKnownLE(const MachineOperand &LHS, const MachineOperand &RHS,
+ const MachineRegisterInfo *MRI);
// Mask assignments for floating-point
static constexpr unsigned FPMASK_Negative_Infinity = 0x001;
diff --git a/llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp b/llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp
index 9b70eb6c25b12..9b4592011eb4c 100644
--- a/llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp
+++ b/llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp
@@ -1347,7 +1347,7 @@ RISCVVLOptimizer::getMinimumVLForUser(const MachineOperand &UserOp) const {
assert(UserOp.getOperandNo() == UserMI.getNumExplicitDefs() &&
RISCVII::isFirstDefTiedToFirstUse(UserMI.getDesc()));
auto DemandedVL = DemandedVLs.lookup(&UserMI);
- if (!DemandedVL || !RISCV::isVLKnownLE(*DemandedVL, VLOp)) {
+ if (!DemandedVL || !RISCV::isVLKnownLE(*DemandedVL, VLOp, MRI)) {
LLVM_DEBUG(dbgs() << " Abort because user is passthru in "
"instruction with demanded tail\n");
return std::nullopt;
@@ -1365,7 +1365,7 @@ RISCVVLOptimizer::getMinimumVLForUser(const MachineOperand &UserOp) const {
// requires.
if (auto DemandedVL = DemandedVLs.lookup(&UserMI)) {
assert(isCandidate(UserMI));
- if (RISCV::isVLKnownLE(*DemandedVL, VLOp))
+ if (RISCV::isVLKnownLE(*DemandedVL, VLOp, MRI))
return DemandedVL;
}
@@ -1408,10 +1408,10 @@ RISCVVLOptimizer::checkUsers(const MachineInstr &MI) const {
// Use the largest VL among all the users. If we cannot determine this
// statically, then we cannot optimize the VL.
- if (!CommonVL || RISCV::isVLKnownLE(*CommonVL, *VLOp)) {
+ if (!CommonVL || RISCV::isVLKnownLE(*CommonVL, *VLOp, MRI)) {
CommonVL = *VLOp;
LLVM_DEBUG(dbgs() << " User VL is: " << VLOp << "\n");
- } else if (!RISCV::isVLKnownLE(*VLOp, *CommonVL)) {
+ } else if (!RISCV::isVLKnownLE(*VLOp, *CommonVL, MRI)) {
LLVM_DEBUG(dbgs() << " Abort because cannot determine a common VL\n");
return std::nullopt;
}
@@ -1464,7 +1464,7 @@ bool RISCVVLOptimizer::tryReduceVL(MachineInstr &MI) const {
assert((CommonVL->isImm() || CommonVL->getReg().isVirtual()) &&
"Expected VL to be an Imm or virtual Reg");
- if (!RISCV::isVLKnownLE(*CommonVL, VLOp)) {
+ if (!RISCV::isVLKnownLE(*CommonVL, VLOp, MRI)) {
LLVM_DEBUG(dbgs() << " Abort due to CommonVL not <= VLOp.\n");
return false;
}
diff --git a/llvm/lib/Target/RISCV/RISCVVectorPeephole.cpp b/llvm/lib/Target/RISCV/RISCVVectorPeephole.cpp
index 62651185137c9..6ea010ebb73d7 100644
--- a/llvm/lib/Target/RISCV/RISCVVectorPeephole.cpp
+++ b/llvm/lib/Target/RISCV/RISCVVectorPeephole.cpp
@@ -177,7 +177,7 @@ bool RISCVVectorPeephole::tryToReduceVL(MachineInstr &MI) const {
MachineOperand &SrcVL =
Src->getOperand(RISCVII::getVLOpNum(Src->getDesc()));
- if (VL.isIdenticalTo(SrcVL) || !RISCV::isVLKnownLE(VL, SrcVL))
+ if (VL.isIdenticalTo(SrcVL) || !RISCV::isVLKnownLE(VL, SrcVL, MRI))
continue;
if (!ensureDominates(VL, *Src))
@@ -440,7 +440,7 @@ bool RISCVVectorPeephole::convertSameMaskVMergeToVMv(MachineInstr &MI) {
const MachineOperand &MIVL = MI.getOperand(RISCVII::getVLOpNum(MI.getDesc()));
const MachineOperand &TrueVL =
True->getOperand(RISCVII::getVLOpNum(True->getDesc()));
- if (!RISCV::isVLKnownLE(MIVL, TrueVL))
+ if (!RISCV::isVLKnownLE(MIVL, TrueVL, MRI))
return false;
// True's passthru needs to be equivalent to False
@@ -611,7 +611,7 @@ bool RISCVVectorPeephole::foldUndefPassthruVMV_V_V(MachineInstr &MI) {
MachineOperand &SrcPolicy =
Src->getOperand(RISCVII::getVecPolicyOpNum(Src->getDesc()));
- if (RISCV::isVLKnownLE(MIVL, SrcVL))
+ if (RISCV::isVLKnownLE(MIVL, SrcVL, MRI))
SrcPolicy.setImm(SrcPolicy.getImm() | RISCVVType::TAIL_AGNOSTIC);
}
@@ -663,7 +663,7 @@ bool RISCVVectorPeephole::foldVMV_V_V(MachineInstr &MI) {
// so we don't need to handle a smaller source VL here. However, the
// user's VL may be larger
MachineOperand &SrcVL = Src->getOperand(RISCVII::getVLOpNum(Src->getDesc()));
- if (!RISCV::isVLKnownLE(SrcVL, MI.getOperand(3)))
+ if (!RISCV::isVLKnownLE(SrcVL, MI.getOperand(3), MRI))
return false;
// If the new passthru doesn't dominate Src, try to move Src so it does.
@@ -684,7 +684,7 @@ bool RISCVVectorPeephole::foldVMV_V_V(MachineInstr &MI) {
// If MI was tail agnostic and the VL didn't increase, preserve it.
int64_t Policy = RISCVVType::TAIL_UNDISTURBED_MASK_UNDISTURBED;
if ((MI.getOperand(5).getImm() & RISCVVType::TAIL_AGNOSTIC) &&
- RISCV::isVLKnownLE(MI.getOperand(3), SrcVL))
+ RISCV::isVLKnownLE(MI.getOperand(3), SrcVL, MRI))
Policy |= RISCVVType::TAIL_AGNOSTIC;
Src->getOperand(RISCVII::getVecPolicyOpNum(Src->getDesc())).setImm(Policy);
}
@@ -775,9 +775,9 @@ bool RISCVVectorPeephole::foldVMergeToMask(MachineInstr &MI) const {
True.getOperand(RISCVII::getVLOpNum(True.getDesc()));
MachineOperand MinVL = MachineOperand::CreateImm(0);
- if (RISCV::isVLKnownLE(TrueVL, VMergeVL))
+ if (RISCV::isVLKnownLE(TrueVL, VMergeVL, MRI))
MinVL = TrueVL;
- else if (RISCV::isVLKnownLE(VMergeVL, TrueVL))
+ else if (RISCV::isVLKnownLE(VMergeVL, TrueVL, MRI))
MinVL = VMergeVL;
else
return false;
@@ -797,7 +797,7 @@ bool RISCVVectorPeephole::foldVMergeToMask(MachineInstr &MI) const {
// to the tail. In that case we always need to use tail undisturbed to
// preserve them.
uint64_t Policy = RISCVVType::TAIL_UNDISTURBED_MASK_UNDISTURBED;
- if (!PassthruReg && RISCV::isVLKnownLE(VMergeVL, MinVL))
+ if (!PassthruReg && RISCV::isVLKnownLE(VMergeVL, MinVL, MRI))
Policy |= RISCVVType::TAIL_AGNOSTIC;
assert(RISCVII::hasVecPolicyOp(True.getDesc().TSFlags) &&
diff --git a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vadd-vp.ll b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vadd-vp.ll
index a66370f5ccc0a..22c629088bacd 100644
--- a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vadd-vp.ll
+++ b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vadd-vp.ll
@@ -413,9 +413,10 @@ define <256 x i8> @vadd_vi_v258i8_unmasked(<256 x i8> %va, i32 zeroext %evl) {
define <256 x i8> @vadd_vi_v258i8_evl129(<256 x i8> %va, <256 x i1> %m) {
; CHECK-LABEL: vadd_vi_v258i8_evl129:
; CHECK: # %bb.0:
-; CHECK-NEXT: li a1, 128
-; CHECK-NEXT: vsetvli zero, a1, e8, m8, ta, ma
+; CHECK-NEXT: vsetivli zero, 1, e8, m8, ta, ma
; CHECK-NEXT: vlm.v v24, (a0)
+; CHECK-NEXT: li a0, 128
+; CHECK-NEXT: vsetvli zero, a0, e8, m8, ta, ma
; CHECK-NEXT: vadd.vi v8, v8, -1, v0.t
; CHECK-NEXT: vmv1r.v v0, v24
; CHECK-NEXT: vsetivli zero, 1, e8, m8, ta, ma
diff --git a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vmax-vp.ll b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vmax-vp.ll
index fec54b36042fa..ec5845752c29c 100644
--- a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vmax-vp.ll
+++ b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vmax-vp.ll
@@ -321,9 +321,10 @@ define <256 x i8> @vmax_vx_v258i8_unmasked(<256 x i8> %va, i8 %b, i32 zeroext %e
define <256 x i8> @vmax_vx_v258i8_evl129(<256 x i8> %va, i8 %b, <256 x i1> %m) {
; CHECK-LABEL: vmax_vx_v258i8_evl129:
; CHECK: # %bb.0:
-; CHECK-NEXT: li a2, 128
-; CHECK-NEXT: vsetvli zero, a2, e8, m8, ta, ma
+; CHECK-NEXT: vsetivli zero, 1, e8, m8, ta, ma
; CHECK-NEXT: vlm.v v24, (a1)
+; CHECK-NEXT: li a1, 128
+; CHECK-NEXT: vsetvli zero, a1, e8, m8, ta, ma
; CHECK-NEXT: vmax.vx v8, v8, a0, v0.t
; CHECK-NEXT: vmv1r.v v0, v24
; CHECK-NEXT: vsetivli zero, 1, e8, m8, ta, ma
diff --git a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vmaxu-vp.ll b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vmaxu-vp.ll
index 7ca0dbd9adffc..2ffd3318d8759 100644
--- a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vmaxu-vp.ll
+++ b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vmaxu-vp.ll
@@ -320,9 +320,10 @@ define <256 x i8> @vmaxu_vx_v258i8_unmasked(<256 x i8> %va, i8 %b, i32 zeroext %
define <256 x i8> @vmaxu_vx_v258i8_evl129(<256 x i8> %va, i8 %b, <256 x i1> %m) {
; CHECK-LABEL: vmaxu_vx_v258i8_evl129:
; CHECK: # %bb.0:
-; CHECK-NEXT: li a2, 128
-; CHECK-NEXT: vsetvli zero, a2, e8, m8, ta, ma
+; CHECK-NEXT: vsetivli zero, 1, e8, m8, ta, ma
; CHECK-NEXT: vlm.v v24, (a1)
+; CHECK-NEXT: li a1, 128
+; CHECK-NEXT: vsetvli zero, a1, e8, m8, ta, ma
; CHECK-NEXT: vmaxu.vx v8, v8, a0, v0.t
; CHECK-NEXT: vmv1r.v v0, v24
; CHECK-NEXT: vsetivli zero, 1, e8, m8, ta, ma
diff --git a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vmin-vp.ll b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vmin-vp.ll
index ea75742ca6e43..53649c77098f2 100644
--- a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vmin-vp.ll
+++ b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vmin-vp.ll
@@ -321,9 +321,10 @@ define <256 x i8> @vmin_vx_v258i8_unmasked(<256 x i8> %va, i8 %b, i32 zeroext %e
define <256 x i8> @vmin_vx_v258i8_evl129(<256 x i8> %va, i8 %b, <256 x i1> %m) {
; CHECK-LABEL: vmin_vx_v258i8_evl129:
; CHECK: # %bb.0:
-; CHECK-NEXT: li a2, 128
-; CHECK-NEXT: vsetvli zero, a2, e8, m8, ta, ma
+; CHECK-NEXT: vsetivli zero, 1, e8, m8, ta, ma
; CHECK-NEXT: vlm.v v24, (a1)
+; CHECK-NEXT: li a1, 128
+; CHECK-NEXT: vsetvli zero, a1, e8, m8, ta, ma
; CHECK-NEXT: vmin.vx v8, v8, a0, v0.t
; CHECK-NEXT: vmv1r.v v0, v24
; CHECK-NEXT: vsetivli zero, 1, e8, m8, ta, ma
diff --git a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vminu-vp.ll b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vminu-vp.ll
index f4f54db64018d..76b5be39f2d93 100644
--- a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vminu-vp.ll
+++ b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vminu-vp.ll
@@ -320,9 +320,10 @@ define <256 x i8> @vminu_vx_v258i8_unmasked(<256 x i8> %va, i8 %b, i32 zeroext %
define <256 x i8> @vminu_vx_v258i8_evl129(<256 x i8> %va, i8 %b, <256 x i1> %m) {
; CHECK-LABEL: vminu_vx_v258i8_evl129:
; CHECK: # %bb.0:
-; CHECK-NEXT: li a2, 128
-; CHECK-NEXT: vsetvli zero, a2, e8, m8, ta, ma
+; CHECK-NEXT: vsetivli zero, 1, e8, m8, ta, ma
; CHECK-NEXT: vlm.v v24, (a1)
+; CHECK-NEXT: li a1, 128
+; CHECK-NEXT: vsetvli zero, a1, e8, m8, ta, ma
; CHECK-NEXT: vminu.vx v8, v8, a0, v0.t
; CHECK-NEXT: vmv1r.v v0, v24
; CHECK-NEXT: vsetivli zero, 1, e8, m8, ta, ma
diff --git a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vsadd-vp.ll b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vsadd-vp.ll
index 902001a376d6a..6ceb03c765fd7 100644
--- a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vsadd-vp.ll
+++ b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vsadd-vp.ll
@@ -422,9 +422,10 @@ define <256 x i8> @vsadd_vi_v258i8_unmasked(<256 x i8> %va, i32 zeroext %evl) {
define <256 x i8> @vsadd_vi_v258i8_evl129(<256 x i8> %va, <256 x i1> %m) {
; CHECK-LABEL: vsadd_vi_v258i8_evl129:
; CHECK: # %bb.0:
-; CHECK-NEXT: li a1, 128
-; CHECK-NEXT: vsetvli zero, a1, e8, m8, ta, ma
+; CHECK-NEXT: vsetivli zero, 1, e8, m8, ta, ma
; CHECK-NEXT: vlm.v v24, (a0)
+; CHECK-NEXT: li a0, 128
+; CHECK-NEXT: vsetvli zero, a0, e8, m8, ta, ma
; CHECK-NEXT: vsadd.vi v8, v8, -1, v0.t
; CHECK-NEXT: vmv1r.v v0, v24
; CHECK-NEXT: vsetivli zero, 1, e8, m8, ta, ma
diff --git a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vsaddu-vp.ll b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vsaddu-vp.ll
index 57292147a0140..2839efd40305b 100644
--- a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vsaddu-vp.ll
+++ b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vsaddu-vp.ll
@@ -418,9 +418,10 @@ define <256 x i8> @vsaddu_vi_v258i8_unmasked(<256 x i8> %va, i32 zeroext %evl) {
define <256 x i8> @vsaddu_vi_v258i8_evl129(<256 x i8> %va, <256 x i1> %m) {
; CHECK-LABEL: vsaddu_vi_v258i8_evl129:
; CHECK: # %bb.0:
-; CHECK-NEXT: li a1, 128
-; CHECK-NEXT: vsetvli zero, a1, e8, m8, ta, ma
+; CHECK-NEXT: vsetivli zero, 1, e8, m8, ta, ma
; CHECK-NEXT: vlm.v v24, (a0)
+; CHECK-NEXT: li a0, 128
+; CHECK-NEXT: vsetvli zero, a0, e8, m8, ta, ma
; CHECK-NEXT: vsaddu.vi v8, v8, -1, v0.t
; CHECK-NEXT: vmv1r.v v0, v24
; CHECK-NEXT: vsetivli zero, 1, e8, m8, ta, ma
diff --git a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vselect-vp.ll b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vselect-vp.ll
index 7b2dcbb025f8f..93f024c2b77a5 100644
--- a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vselect-vp.ll
+++ b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vselect-vp.ll
@@ -203,38 +203,21 @@ define <256 x i8> @select_v256i8(<256 x i1> %a, <256 x i8> %b, <256 x i8> %c, i3
define <256 x i8> @select_evl_v256i8(<256 x i1> %a, <256 x i8> %b, <256 x i8> %c) {
; CHECK-LABEL: select_evl_v256i8:
; CHECK: # %bb.0:
-; CHECK-NEXT: addi sp, sp, -16
-; CHECK-NEXT: .cfi_def_cfa_offset 16
-; CHECK-NEXT: csrr a2, vlenb
-; CHECK-NEXT: slli a2, a2, 3
-; CHECK-NEXT: sub sp, sp, a2
-; CHECK-NEXT: .cfi_escape 0x0f, 0x0d, 0x72, 0x00, 0x11, 0x10, 0x22, 0x11, 0x08, 0x92, 0xa2, 0x38, 0x00, 0x1e, 0x22 # sp + 16 + 8 * vlenb
-; CHECK-NEXT: addi a2, sp, 16
-; CHECK-NEXT: vs8r.v v16, (a2) # vscale x 64-byte Folded Spill
; CHECK-NEXT: vsetivli zero, 1, e8, m1, ta, ma
; CHECK-NEXT: vmv1r.v v7, v8
+; CHECK-NEXT: vmv1r.v v6, v0
; CHECK-NEXT: li a2, 128
+; CHECK-NEXT: addi a3, a1, 128
; CHECK-NEXT: vsetvli zero, a2, e8, m8, ta, ma
-; CHECK-NEXT: vle8.v v24, (a0)
-; CHECK-NEXT: addi a0, a1, 128
-; CHECK-NEXT: vle8.v v8, (a0)
-; CHECK-NEXT: vle8.v v16, (a1)
-; CHECK-NEXT: vmv1r.v v6, v0
+; CHECK-NEXT: vle8.v v24, (a3)
+; CHECK-NEXT: vle8.v v8, (a1)
; CHECK-NEXT: vmv1r.v v0, v7
-; CHECK-NEXT: vsetivli zero, 1, e8, m8, ta, ma
-; CHECK-NEXT: vmerge.vvm v24, v8, v24, v0
+; CHECK-NEXT: vsetivli zero, 1, e8, m8, ta, mu
+; CHECK-NEXT: vle8.v v24, (a0), v0.t
; CHECK-NEXT: vmv1r.v v0, v6
-; CHECK-NEXT: addi a0, sp, 16
-; CHECK-NEXT: vl8r.v v8, (a0) # vscale x 64-byte Folded Reload
; CHECK-NEXT: vsetvli zero, a2, e8, m8, ta, ma
-; CHECK-NEXT: vmerge.vvm v8, v16, v8, v0
+; CHECK-NEXT: vmerge.vvm v8, v8, v16, v0
; CHECK-NEXT: vmv8r.v v16, v24
-; CHECK-NEXT: csrr a0, vlenb
-; CHECK-NEXT: slli a0, a0, 3
-; CHECK-NEXT: add sp, sp, a0
-; CHECK-NEXT: .cfi_def_cfa sp, 16
-; CHECK-NEXT: addi sp, sp, 16
-; CHECK-NEXT: .cfi_def_cfa_offset 0
; CHECK-NEXT: ret
%v = call <256 x i8> @llvm.vp.select.v256i8(<256 x i1> %a, <256 x i8> %b, <256 x i8> %c, i32 129)
ret <256 x i8> %v
diff --git a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vssub-vp.ll b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vssub-vp.ll
index 353042fc889e5..79856de033060 100644
--- a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vssub-vp.ll
+++ b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vssub-vp.ll
@@ -436,14 +436,15 @@ define <256 x i8> @vssub_vi_v258i8_unmasked(<256 x i8> %va, i32 zeroext %evl) {
define <256 x i8> @vssub_vi_v258i8_evl129(<256 x i8> %va, <256 x i1> %m) {
; CHECK-LABEL: vssub_vi_v258i8_evl129:
; CHECK: # %bb.0:
-; CHECK-NEXT: li a1, 128
-; CHECK-NEXT: vsetvli zero, a1, e8, m8, ta, ma
+; CHECK-NEXT: vsetivli zero, 1, e8, m8, ta, ma
; CHECK-NEXT: vlm.v v24, (a0)
-; CHECK-NEXT: li a0, -1
-; CHECK-NEXT: vssub.vx v8, v8, a0, v0.t
+; CHECK-NEXT: li a0, 128
+; CHECK-NEXT: li a1, -1
+; CHECK-NEXT: vsetvli zero, a0, e8, m8, ta, ma
+; CHECK-NEXT: vssub.vx v8, v8, a1, v0.t
; CHECK-NEXT: vmv1r.v v0, v24
; CHECK-NEXT: vsetivli zero, 1, e8, m8, ta, ma
-; CHECK-NEXT: vssub.vx v16, v16, a0, v0.t
+; CHECK-NEXT: vssub.vx v16, v16, a1, v0.t
; CHECK-NEXT: ret
%v = call <256 x i8> @llvm.vp.ssub.sat.v258i8(<256 x i8> %va, <256 x i8> splat (i8 -1), <256 x i1> %m, i32 129)
ret <256 x i8> %v
diff --git a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vssubu-vp.ll b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vssubu-vp.ll
index c00fb329b2f0c..7a9bef49c994d 100644
--- a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vssubu-vp.ll
+++ b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vssubu-vp.ll
@@ -431,14 +431,15 @@ define <256 x i8> @vssubu_vi_v258i8_unmasked(<256 x i8> %va, i32 zeroext %evl) {
define <256 x i8> @vssubu_vi_v258i8_evl129(<256 x i8> %va, <256 x i1> %m) {
; CHECK-LABEL: vssubu_vi_v258i8_evl129:
; CHECK: # %bb.0:
-; CHECK-NEXT: li a1, 128
-; CHECK-NEXT: vsetvli zero, a1, e8, m8, ta, ma
+; CHECK-NEXT: vsetivli zero, 1, e8, m8, ta, ma
; CHECK-NEXT: vlm.v v24, (a0)
-; CHECK-NEXT: li a0, -1
-; CHECK-NEXT: vssubu.vx v8, v8, a0, v0.t
+; CHECK-NEXT: li a0, 128
+; CHECK-NEXT: li a1, -1
+; CHECK-NEXT: vsetvli zero, a0, e8, m8, ta, ma
+; CHECK-NEXT: vssubu.vx v8, v8, a1, v0.t
; CHECK-NEXT: vmv1r.v v0, v24
; CHECK-NEXT: vsetivli zero, 1, e8, m8, ta, ma
-; CHECK-NEXT: vssubu.vx v16, v16, a0, v0.t
+; CHECK-NEXT: vssubu.vx v16, v16, a1, v0.t
; CHECK-NEXT: ret
%v = call <256 x i8> @llvm.vp.usub.sat.v258i8(<256 x i8> %va, <256 x i8> splat (i8 -1), <256 x i1> %m, i32 129)
ret <256 x i8> %v
diff --git a/llvm/test/CodeGen/RISCV/rvv/vmv.v.v-peephole.ll b/llvm/test/CodeGen/RISCV/rvv/vmv.v.v-peephole.ll
index 1c7b13db624d5..89cd53977312c 100644
--- a/llvm/test/CodeGen/RISCV/rvv/vmv.v.v-peephole.ll
+++ b/llvm/test/CodeGen/RISCV/rvv/vmv.v.v-peephole.ll
@@ -87,11 +87,7 @@ define <vscale x 4 x i32> @diff_avl_non_uimm5(<vscale x 4 x i32> %passthru, <vsc
; CHECK: # %bb.0:
; CHECK-NEXT: li a0, 42
; CHECK-NEXT: vsetvli zero, a0, e32, m2, tu, ma
-; CHECK-NEXT: vmv2r.v v14, v8
-; CHECK-NEXT: vadd.vv v14, v10, v12
-; CHECK-NEXT: li a0, 123
-; CHECK-NEXT: vsetvli zero, a0, e32, m2, tu, ma
-; CHECK-NEXT: vmv.v.v v8, v14
+; CHECK-NEXT: vadd.vv v8, v10, v12
; CHECK-NEXT: ret
%v = call <vscale x 4 x i32> @llvm.riscv.vadd.nxv4i32.nxv4i32(<vscale x 4 x i32> %passthru, <vscale x 4 x i32> %a, <vscale x 4 x i32> %b, iXLen 42)
%w = call <vscale x 4 x i32> @llvm.riscv.vmv.v.v.nxv4i32(<vscale x 4 x i32> %passthru, <vscale x 4 x i32> %v, iXLen 123)
>From 8072205c42c5320d1a1eaf7dc4d58b796c9d3ce8 Mon Sep 17 00:00:00 2001
From: Luke Lau <luke at igalia.com>
Date: Wed, 3 Sep 2025 18:29:21 +0800
Subject: [PATCH 3/4] Don't consider ADDI for sentinel value
---
llvm/lib/Target/RISCV/RISCVInstrInfo.cpp | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
index 0a86406d1c14b..832a6b4a99844 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
@@ -4814,14 +4814,14 @@ bool RISCV::isVLKnownLE(const MachineOperand &LHS, const MachineOperand &RHS,
if (LHS.isReg() && RHS.isReg() && LHS.getReg().isVirtual() &&
LHS.getReg() == RHS.getReg())
return true;
- std::optional<int64_t> LHSImm = getEffectiveImm(LHS, MRI),
- RHSImm = getEffectiveImm(RHS, MRI);
- if (RHSImm == RISCV::VLMaxSentinel)
+ if (RHS.isImm() && RHS.getImm() == RISCV::VLMaxSentinel)
return true;
- if (LHSImm == 0)
+ if (LHS.isImm() && LHS.getImm() == 0)
return true;
- if (LHSImm == RISCV::VLMaxSentinel)
+ if (LHS.isImm() && LHS.getImm() == RISCV::VLMaxSentinel)
return false;
+ std::optional<int64_t> LHSImm = getEffectiveImm(LHS, MRI),
+ RHSImm = getEffectiveImm(RHS, MRI);
if (!LHSImm || !RHSImm)
return false;
return LHSImm <= RHSImm;
>From a6c215c07cb6241c7407ef01c4b51fbe619a4337 Mon Sep 17 00:00:00 2001
From: Luke Lau <luke at igalia.com>
Date: Thu, 4 Sep 2025 01:32:17 +0800
Subject: [PATCH 4/4] Reuse isLoadImm, assert MRI is in SSA
---
llvm/lib/Target/RISCV/RISCVInstrInfo.cpp | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
index 832a6b4a99844..872f2cff67e58 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
@@ -4801,16 +4801,17 @@ static std::optional<int64_t> getEffectiveImm(const MachineOperand &MO,
assert(MO.isImm() || MO.getReg().isVirtual());
if (MO.isImm())
return MO.getImm();
- MachineInstr *Def = MRI->getVRegDef(MO.getReg());
- if (Def->getOpcode() == RISCV::ADDI &&
- Def->getOperand(1).getReg() == RISCV::X0)
- return Def->getOperand(2).getImm();
+ const MachineInstr *Def = MRI->getVRegDef(MO.getReg());
+ int64_t Imm;
+ if (isLoadImm(Def, Imm))
+ return Imm;
return std::nullopt;
}
-/// Given two VL operands, do we know that LHS <= RHS?
+/// Given two VL operands, do we know that LHS <= RHS? Must be used in SSA form.
bool RISCV::isVLKnownLE(const MachineOperand &LHS, const MachineOperand &RHS,
const MachineRegisterInfo *MRI) {
+ assert(MRI->isSSA());
if (LHS.isReg() && RHS.isReg() && LHS.getReg().isVirtual() &&
LHS.getReg() == RHS.getReg())
return true;
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