[llvm] [RISCV] Eliminate dead li after emitting VSETVLIs (PR #65934)
Yingwei Zheng via llvm-commits
llvm-commits at lists.llvm.org
Mon Nov 13 04:38:56 PST 2023
https://github.com/dtcxzyw updated https://github.com/llvm/llvm-project/pull/65934
>From f38258e02be8195abf31b36772b1b75337e27a09 Mon Sep 17 00:00:00 2001
From: Yingwei Zheng <dtcxzyw2333 at gmail.com>
Date: Mon, 13 Nov 2023 20:37:18 +0800
Subject: [PATCH] [RISCV] Eliminate dead li after emitting VSETVLIs
---
llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp | 12 ++++++----
llvm/lib/Target/RISCV/RISCVInstrInfo.cpp | 8 +++++++
llvm/lib/Target/RISCV/RISCVInstrInfo.h | 2 ++
.../RISCV/rvv/fixed-vectors-masked-gather.ll | 24 -------------------
4 files changed, 18 insertions(+), 28 deletions(-)
diff --git a/llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp b/llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp
index 999ff9920716e87..8c5084396c9b595 100644
--- a/llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp
+++ b/llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp
@@ -487,10 +487,7 @@ class VSETVLIInfo {
if (getAVLReg() == RISCV::X0)
return true;
if (MachineInstr *MI = MRI.getVRegDef(getAVLReg());
- MI && MI->getOpcode() == RISCV::ADDI &&
- MI->getOperand(1).isReg() && MI->getOperand(2).isImm() &&
- MI->getOperand(1).getReg() == RISCV::X0 &&
- MI->getOperand(2).getImm() != 0)
+ MI && RISCV::isLoadSImm12(*MI, /*NonZero*/ true))
return true;
return false;
}
@@ -1262,9 +1259,16 @@ void RISCVInsertVSETVLI::emitVSETVLIs(MachineBasicBlock &MBB) {
if (RISCVII::hasVLOp(TSFlags)) {
MachineOperand &VLOp = MI.getOperand(getVLOpNum(MI));
if (VLOp.isReg()) {
+ MachineInstr *VLOpDef = MRI->getVRegDef(VLOp.getReg());
+
// Erase the AVL operand from the instruction.
VLOp.setReg(RISCV::NoRegister);
VLOp.setIsKill(false);
+
+ // If the old VLOp was only used by MI, it's dead.
+ if (VLOpDef && RISCV::isLoadSImm12(*VLOpDef, /*NonZero*/ true) &&
+ MRI->use_nodbg_empty(VLOpDef->getOperand(0).getReg()))
+ VLOpDef->eraseFromParent();
}
MI.addOperand(MachineOperand::CreateReg(RISCV::VL, /*isDef*/ false,
/*isImp*/ true));
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
index 9271f807a84838b..27bd60d566af5c4 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
@@ -3048,6 +3048,14 @@ bool RISCV::isZEXT_B(const MachineInstr &MI) {
MI.getOperand(2).isImm() && MI.getOperand(2).getImm() == 255;
}
+// Returns true if this is the li rd, simm12 pattern, addi rd, x0, simm12.
+bool RISCV::isLoadSImm12(const MachineInstr &MI, bool NonZero) {
+ return MI.getOpcode() == RISCV::ADDI && MI.getOperand(1).isReg() &&
+ MI.getOperand(1).getReg() == RISCV::X0 &&
+ (!NonZero ||
+ (MI.getOperand(2).isImm() && MI.getOperand(2).getImm() != 0));
+}
+
static bool isRVVWholeLoadStore(unsigned Opcode) {
switch (Opcode) {
default:
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfo.h b/llvm/lib/Target/RISCV/RISCVInstrInfo.h
index b33d8c28561596b..ddde4b24bc7d5cf 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfo.h
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfo.h
@@ -263,6 +263,8 @@ namespace RISCV {
bool isSEXT_W(const MachineInstr &MI);
bool isZEXT_W(const MachineInstr &MI);
bool isZEXT_B(const MachineInstr &MI);
+// Returns true if this is the li rd, simm12 pattern, addi rd, x0, simm12.
+bool isLoadSImm12(const MachineInstr &MI, bool NonZero);
// Returns true if the given MI is an RVV instruction opcode for which we may
// expect to see a FrameIndex operand.
diff --git a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-masked-gather.ll b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-masked-gather.ll
index 728cf18e1a77d8a..c8706f841639d60 100644
--- a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-masked-gather.ll
+++ b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-masked-gather.ll
@@ -12434,7 +12434,6 @@ define <32 x i8> @mgather_baseidx_v32i8(ptr %base, <32 x i8> %idxs, <32 x i1> %m
; RV64ZVE32F-NEXT: vmv.x.s a2, v12
; RV64ZVE32F-NEXT: add a2, a0, a2
; RV64ZVE32F-NEXT: lbu a2, 0(a2)
-; RV64ZVE32F-NEXT: li a3, 32
; RV64ZVE32F-NEXT: vmv.s.x v12, a2
; RV64ZVE32F-NEXT: vsetivli zero, 2, e8, m1, tu, ma
; RV64ZVE32F-NEXT: vslideup.vi v10, v12, 1
@@ -12472,7 +12471,6 @@ define <32 x i8> @mgather_baseidx_v32i8(ptr %base, <32 x i8> %idxs, <32 x i1> %m
; RV64ZVE32F-NEXT: vmv.x.s a2, v14
; RV64ZVE32F-NEXT: add a2, a0, a2
; RV64ZVE32F-NEXT: lbu a2, 0(a2)
-; RV64ZVE32F-NEXT: li a3, 32
; RV64ZVE32F-NEXT: vmv.s.x v14, a2
; RV64ZVE32F-NEXT: vsetivli zero, 6, e8, m1, tu, ma
; RV64ZVE32F-NEXT: vslideup.vi v10, v14, 5
@@ -12496,7 +12494,6 @@ define <32 x i8> @mgather_baseidx_v32i8(ptr %base, <32 x i8> %idxs, <32 x i1> %m
; RV64ZVE32F-NEXT: vmv.x.s a2, v13
; RV64ZVE32F-NEXT: add a2, a0, a2
; RV64ZVE32F-NEXT: lbu a2, 0(a2)
-; RV64ZVE32F-NEXT: li a3, 32
; RV64ZVE32F-NEXT: vmv.s.x v13, a2
; RV64ZVE32F-NEXT: vsetivli zero, 10, e8, m1, tu, ma
; RV64ZVE32F-NEXT: vslideup.vi v10, v13, 9
@@ -12511,7 +12508,6 @@ define <32 x i8> @mgather_baseidx_v32i8(ptr %base, <32 x i8> %idxs, <32 x i1> %m
; RV64ZVE32F-NEXT: vmv.x.s a2, v12
; RV64ZVE32F-NEXT: add a2, a0, a2
; RV64ZVE32F-NEXT: lbu a2, 0(a2)
-; RV64ZVE32F-NEXT: li a3, 32
; RV64ZVE32F-NEXT: vmv.s.x v14, a2
; RV64ZVE32F-NEXT: vsetivli zero, 11, e8, m1, tu, ma
; RV64ZVE32F-NEXT: vslideup.vi v10, v14, 10
@@ -12524,7 +12520,6 @@ define <32 x i8> @mgather_baseidx_v32i8(ptr %base, <32 x i8> %idxs, <32 x i1> %m
; RV64ZVE32F-NEXT: vmv.x.s a2, v12
; RV64ZVE32F-NEXT: add a2, a0, a2
; RV64ZVE32F-NEXT: lbu a2, 0(a2)
-; RV64ZVE32F-NEXT: li a3, 32
; RV64ZVE32F-NEXT: vmv.s.x v12, a2
; RV64ZVE32F-NEXT: vsetivli zero, 12, e8, m1, tu, ma
; RV64ZVE32F-NEXT: vslideup.vi v10, v12, 11
@@ -12537,7 +12532,6 @@ define <32 x i8> @mgather_baseidx_v32i8(ptr %base, <32 x i8> %idxs, <32 x i1> %m
; RV64ZVE32F-NEXT: vmv.x.s a2, v13
; RV64ZVE32F-NEXT: add a2, a0, a2
; RV64ZVE32F-NEXT: lbu a2, 0(a2)
-; RV64ZVE32F-NEXT: li a3, 32
; RV64ZVE32F-NEXT: vmv.s.x v9, a2
; RV64ZVE32F-NEXT: vsetivli zero, 13, e8, m1, tu, ma
; RV64ZVE32F-NEXT: vslideup.vi v10, v9, 12
@@ -12550,7 +12544,6 @@ define <32 x i8> @mgather_baseidx_v32i8(ptr %base, <32 x i8> %idxs, <32 x i1> %m
; RV64ZVE32F-NEXT: vmv.x.s a2, v9
; RV64ZVE32F-NEXT: add a2, a0, a2
; RV64ZVE32F-NEXT: lbu a2, 0(a2)
-; RV64ZVE32F-NEXT: li a3, 32
; RV64ZVE32F-NEXT: vmv.s.x v9, a2
; RV64ZVE32F-NEXT: vsetivli zero, 14, e8, m1, tu, ma
; RV64ZVE32F-NEXT: vslideup.vi v10, v9, 13
@@ -12574,7 +12567,6 @@ define <32 x i8> @mgather_baseidx_v32i8(ptr %base, <32 x i8> %idxs, <32 x i1> %m
; RV64ZVE32F-NEXT: vmv.x.s a2, v9
; RV64ZVE32F-NEXT: add a2, a0, a2
; RV64ZVE32F-NEXT: lbu a2, 0(a2)
-; RV64ZVE32F-NEXT: li a3, 32
; RV64ZVE32F-NEXT: vmv.s.x v12, a2
; RV64ZVE32F-NEXT: vsetivli zero, 18, e8, m2, tu, ma
; RV64ZVE32F-NEXT: vslideup.vi v10, v12, 17
@@ -12612,7 +12604,6 @@ define <32 x i8> @mgather_baseidx_v32i8(ptr %base, <32 x i8> %idxs, <32 x i1> %m
; RV64ZVE32F-NEXT: vmv.x.s a2, v12
; RV64ZVE32F-NEXT: add a2, a0, a2
; RV64ZVE32F-NEXT: lbu a2, 0(a2)
-; RV64ZVE32F-NEXT: li a3, 32
; RV64ZVE32F-NEXT: vmv.s.x v12, a2
; RV64ZVE32F-NEXT: vsetivli zero, 22, e8, m2, tu, ma
; RV64ZVE32F-NEXT: vslideup.vi v10, v12, 21
@@ -12636,7 +12627,6 @@ define <32 x i8> @mgather_baseidx_v32i8(ptr %base, <32 x i8> %idxs, <32 x i1> %m
; RV64ZVE32F-NEXT: vmv.x.s a2, v9
; RV64ZVE32F-NEXT: add a2, a0, a2
; RV64ZVE32F-NEXT: lbu a2, 0(a2)
-; RV64ZVE32F-NEXT: li a3, 32
; RV64ZVE32F-NEXT: vmv.s.x v12, a2
; RV64ZVE32F-NEXT: vsetivli zero, 26, e8, m2, tu, ma
; RV64ZVE32F-NEXT: vslideup.vi v10, v12, 25
@@ -12662,7 +12652,6 @@ define <32 x i8> @mgather_baseidx_v32i8(ptr %base, <32 x i8> %idxs, <32 x i1> %m
; RV64ZVE32F-NEXT: vmv.x.s a2, v8
; RV64ZVE32F-NEXT: add a2, a0, a2
; RV64ZVE32F-NEXT: lbu a2, 0(a2)
-; RV64ZVE32F-NEXT: li a3, 32
; RV64ZVE32F-NEXT: vmv.s.x v12, a2
; RV64ZVE32F-NEXT: vsetivli zero, 30, e8, m2, tu, ma
; RV64ZVE32F-NEXT: vslideup.vi v10, v12, 29
@@ -12675,7 +12664,6 @@ define <32 x i8> @mgather_baseidx_v32i8(ptr %base, <32 x i8> %idxs, <32 x i1> %m
; RV64ZVE32F-NEXT: vmv.x.s a2, v8
; RV64ZVE32F-NEXT: add a2, a0, a2
; RV64ZVE32F-NEXT: lbu a2, 0(a2)
-; RV64ZVE32F-NEXT: li a3, 32
; RV64ZVE32F-NEXT: vmv.s.x v12, a2
; RV64ZVE32F-NEXT: vsetivli zero, 31, e8, m2, tu, ma
; RV64ZVE32F-NEXT: vslideup.vi v10, v12, 30
@@ -12700,7 +12688,6 @@ define <32 x i8> @mgather_baseidx_v32i8(ptr %base, <32 x i8> %idxs, <32 x i1> %m
; RV64ZVE32F-NEXT: vmv.x.s a2, v12
; RV64ZVE32F-NEXT: add a2, a0, a2
; RV64ZVE32F-NEXT: lbu a2, 0(a2)
-; RV64ZVE32F-NEXT: li a3, 32
; RV64ZVE32F-NEXT: vmv.s.x v14, a2
; RV64ZVE32F-NEXT: vsetivli zero, 3, e8, m1, tu, ma
; RV64ZVE32F-NEXT: vslideup.vi v10, v14, 2
@@ -12712,7 +12699,6 @@ define <32 x i8> @mgather_baseidx_v32i8(ptr %base, <32 x i8> %idxs, <32 x i1> %m
; RV64ZVE32F-NEXT: vmv.x.s a2, v12
; RV64ZVE32F-NEXT: add a2, a0, a2
; RV64ZVE32F-NEXT: lbu a2, 0(a2)
-; RV64ZVE32F-NEXT: li a3, 32
; RV64ZVE32F-NEXT: vmv.s.x v12, a2
; RV64ZVE32F-NEXT: vsetivli zero, 4, e8, m1, tu, ma
; RV64ZVE32F-NEXT: vslideup.vi v10, v12, 3
@@ -12723,7 +12709,6 @@ define <32 x i8> @mgather_baseidx_v32i8(ptr %base, <32 x i8> %idxs, <32 x i1> %m
; RV64ZVE32F-NEXT: vmv.x.s a2, v13
; RV64ZVE32F-NEXT: add a2, a0, a2
; RV64ZVE32F-NEXT: lbu a2, 0(a2)
-; RV64ZVE32F-NEXT: li a3, 32
; RV64ZVE32F-NEXT: vmv.s.x v14, a2
; RV64ZVE32F-NEXT: vsetivli zero, 7, e8, m1, tu, ma
; RV64ZVE32F-NEXT: vslideup.vi v10, v14, 6
@@ -12735,7 +12720,6 @@ define <32 x i8> @mgather_baseidx_v32i8(ptr %base, <32 x i8> %idxs, <32 x i1> %m
; RV64ZVE32F-NEXT: vmv.x.s a2, v13
; RV64ZVE32F-NEXT: add a2, a0, a2
; RV64ZVE32F-NEXT: lbu a2, 0(a2)
-; RV64ZVE32F-NEXT: li a3, 32
; RV64ZVE32F-NEXT: vmv.s.x v13, a2
; RV64ZVE32F-NEXT: vsetivli zero, 8, e8, m1, tu, ma
; RV64ZVE32F-NEXT: vslideup.vi v10, v13, 7
@@ -12758,7 +12742,6 @@ define <32 x i8> @mgather_baseidx_v32i8(ptr %base, <32 x i8> %idxs, <32 x i1> %m
; RV64ZVE32F-NEXT: vmv.x.s a2, v9
; RV64ZVE32F-NEXT: add a2, a0, a2
; RV64ZVE32F-NEXT: lbu a2, 0(a2)
-; RV64ZVE32F-NEXT: li a3, 32
; RV64ZVE32F-NEXT: vmv.s.x v12, a2
; RV64ZVE32F-NEXT: vsetivli zero, 15, e8, m1, tu, ma
; RV64ZVE32F-NEXT: vslideup.vi v10, v12, 14
@@ -12770,7 +12753,6 @@ define <32 x i8> @mgather_baseidx_v32i8(ptr %base, <32 x i8> %idxs, <32 x i1> %m
; RV64ZVE32F-NEXT: vmv.x.s a2, v9
; RV64ZVE32F-NEXT: add a2, a0, a2
; RV64ZVE32F-NEXT: lbu a2, 0(a2)
-; RV64ZVE32F-NEXT: li a3, 32
; RV64ZVE32F-NEXT: vmv.s.x v9, a2
; RV64ZVE32F-NEXT: vsetivli zero, 16, e8, m1, tu, ma
; RV64ZVE32F-NEXT: vslideup.vi v10, v9, 15
@@ -12793,7 +12775,6 @@ define <32 x i8> @mgather_baseidx_v32i8(ptr %base, <32 x i8> %idxs, <32 x i1> %m
; RV64ZVE32F-NEXT: vmv.x.s a2, v12
; RV64ZVE32F-NEXT: add a2, a0, a2
; RV64ZVE32F-NEXT: lbu a2, 0(a2)
-; RV64ZVE32F-NEXT: li a3, 32
; RV64ZVE32F-NEXT: vmv.s.x v14, a2
; RV64ZVE32F-NEXT: vsetivli zero, 19, e8, m2, tu, ma
; RV64ZVE32F-NEXT: vslideup.vi v10, v14, 18
@@ -12805,7 +12786,6 @@ define <32 x i8> @mgather_baseidx_v32i8(ptr %base, <32 x i8> %idxs, <32 x i1> %m
; RV64ZVE32F-NEXT: vmv.x.s a2, v12
; RV64ZVE32F-NEXT: add a2, a0, a2
; RV64ZVE32F-NEXT: lbu a2, 0(a2)
-; RV64ZVE32F-NEXT: li a3, 32
; RV64ZVE32F-NEXT: vmv.s.x v12, a2
; RV64ZVE32F-NEXT: vsetivli zero, 20, e8, m2, tu, ma
; RV64ZVE32F-NEXT: vslideup.vi v10, v12, 19
@@ -12816,7 +12796,6 @@ define <32 x i8> @mgather_baseidx_v32i8(ptr %base, <32 x i8> %idxs, <32 x i1> %m
; RV64ZVE32F-NEXT: vmv.x.s a2, v9
; RV64ZVE32F-NEXT: add a2, a0, a2
; RV64ZVE32F-NEXT: lbu a2, 0(a2)
-; RV64ZVE32F-NEXT: li a3, 32
; RV64ZVE32F-NEXT: vmv.s.x v12, a2
; RV64ZVE32F-NEXT: vsetivli zero, 23, e8, m2, tu, ma
; RV64ZVE32F-NEXT: vslideup.vi v10, v12, 22
@@ -12828,7 +12807,6 @@ define <32 x i8> @mgather_baseidx_v32i8(ptr %base, <32 x i8> %idxs, <32 x i1> %m
; RV64ZVE32F-NEXT: vmv.x.s a2, v9
; RV64ZVE32F-NEXT: add a2, a0, a2
; RV64ZVE32F-NEXT: lbu a2, 0(a2)
-; RV64ZVE32F-NEXT: li a3, 32
; RV64ZVE32F-NEXT: vmv.s.x v12, a2
; RV64ZVE32F-NEXT: vsetivli zero, 24, e8, m2, tu, ma
; RV64ZVE32F-NEXT: vslideup.vi v10, v12, 23
@@ -12851,7 +12829,6 @@ define <32 x i8> @mgather_baseidx_v32i8(ptr %base, <32 x i8> %idxs, <32 x i1> %m
; RV64ZVE32F-NEXT: vmv.x.s a2, v8
; RV64ZVE32F-NEXT: add a2, a0, a2
; RV64ZVE32F-NEXT: lbu a2, 0(a2)
-; RV64ZVE32F-NEXT: li a3, 32
; RV64ZVE32F-NEXT: vmv.s.x v12, a2
; RV64ZVE32F-NEXT: vsetivli zero, 27, e8, m2, tu, ma
; RV64ZVE32F-NEXT: vslideup.vi v10, v12, 26
@@ -12863,7 +12840,6 @@ define <32 x i8> @mgather_baseidx_v32i8(ptr %base, <32 x i8> %idxs, <32 x i1> %m
; RV64ZVE32F-NEXT: vmv.x.s a2, v8
; RV64ZVE32F-NEXT: add a2, a0, a2
; RV64ZVE32F-NEXT: lbu a2, 0(a2)
-; RV64ZVE32F-NEXT: li a3, 32
; RV64ZVE32F-NEXT: vmv.s.x v12, a2
; RV64ZVE32F-NEXT: vsetivli zero, 28, e8, m2, tu, ma
; RV64ZVE32F-NEXT: vslideup.vi v10, v12, 27
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