[llvm] [RISCV][VLOPT] Add support for checkUsers when UserMI is a Single-Width Integer Reduction (PR #120345)
Michael Maitland via llvm-commits
llvm-commits at lists.llvm.org
Tue Dec 17 18:17:49 PST 2024
https://github.com/michaelmaitland updated https://github.com/llvm/llvm-project/pull/120345
>From 464ccb9dba5c8627e9579e6f0ae734ac3c85d61e Mon Sep 17 00:00:00 2001
From: Michael Maitland <michaeltmaitland at gmail.com>
Date: Tue, 17 Dec 2024 17:50:34 -0800
Subject: [PATCH 1/3] [RISCV][VLOPT] Add support for checkUsers when UserMI is
an reduction
Reductions are weird because for some operands, they are vector registers but
only read the first lane. For these operands, we do not need to check to make
sure the EEW and EMUL ratios match. However, we need to make sure that when
the reduction instruction has a non-zero VL operand, we don't try and set the
CommonVL=0. Since this is an edge case, we decide just not to optimize anything
when this occurs.
---
llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp | 42 +++++++++++++++++--
.../test/CodeGen/RISCV/rvv/vl-opt-op-info.mir | 20 +++++++++
llvm/test/CodeGen/RISCV/rvv/vl-opt.mir | 12 ++++++
3 files changed, 70 insertions(+), 4 deletions(-)
diff --git a/llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp b/llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp
index a9e5bb6ecd9b8a..fb020e361b4cee 100644
--- a/llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp
+++ b/llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp
@@ -568,6 +568,23 @@ static OperandInfo getOperandInfo(const MachineOperand &MO,
return OperandInfo(MIVLMul, MILog2SEW);
}
+ // Vector Reduction Operations
+ // Vector Single-Width Integer Reduction Instructions
+ // The Dest and VS1 only read element 0 of the vector register. Return unknown
+ // for these. VS2 has EEW=SEW and EMUL=LMUL.
+ case RISCV::VREDAND_VS:
+ case RISCV::VREDMAX_VS:
+ case RISCV::VREDMAXU_VS:
+ case RISCV::VREDMIN_VS:
+ case RISCV::VREDMINU_VS:
+ case RISCV::VREDOR_VS:
+ case RISCV::VREDSUM_VS:
+ case RISCV::VREDXOR_VS: {
+ if (MO.getOperandNo() == 2)
+ return OperandInfo(MIVLMul, MILog2SEW);
+ return {};
+ }
+
default:
return {};
}
@@ -886,11 +903,28 @@ bool RISCVVLOptimizer::checkUsers(const MachineOperand *&CommonVL,
// Instructions like reductions may use a vector register as a scalar
// register. In this case, we should treat it like a scalar register which
- // does not impact the decision on whether to optimize VL.
- // TODO: Treat it like a scalar register instead of bailing out.
+ // does not impact the decision on whether to optimize VL. But if there is
+ // another user of MI and it has VL=0, we need to be sure not to reduce the
+ // VL of MI to zero when the VLOp of UserOp is may be non-zero.
if (isVectorOpUsedAsScalarOp(UserOp)) {
- CanReduceVL = false;
- break;
+ [[maybe_unused]] Register R = UserOp.getReg();
+ [[maybe_unused]] const TargetRegisterClass *RC = MRI->getRegClass(R);
+ assert(RISCV::VRRegClass.hasSubClassEq(RC) &&
+ "Expect LMUL 1 register class for vector as scalar operands!");
+ LLVM_DEBUG(dbgs() << " Used this operand as a scalar operand\n");
+ const MCInstrDesc &Desc = UserMI.getDesc();
+ unsigned VLOpNum = RISCVII::getVLOpNum(Desc);
+ const MachineOperand &VLOp = UserMI.getOperand(VLOpNum);
+ if ((VLOp.isReg() && VLOp.getReg() != RISCV::X0) ||
+ (VLOp.isImm() && VLOp.getImm() != 0)) {
+ if (!CommonVL) {
+ CommonVL = &VLOp;
+ continue;
+ } else if (!CommonVL->isIdenticalTo(VLOp)) {
+ CanReduceVL = false;
+ break;
+ }
+ }
}
if (mayReadPastVL(UserMI)) {
diff --git a/llvm/test/CodeGen/RISCV/rvv/vl-opt-op-info.mir b/llvm/test/CodeGen/RISCV/rvv/vl-opt-op-info.mir
index 8587ec136afd83..e151d82e4d6217 100644
--- a/llvm/test/CodeGen/RISCV/rvv/vl-opt-op-info.mir
+++ b/llvm/test/CodeGen/RISCV/rvv/vl-opt-op-info.mir
@@ -892,3 +892,23 @@ body: |
%x:vr = PseudoVADD_VV_M1 $noreg, $noreg, $noreg, -1, 3 /* e8 */, 0
%y:vr = PseudoVMV_V_V_MF2 $noreg, %x, 1, 3 /* e8 */, 0
...
+---
+name: vred_vs2
+body: |
+ bb.0:
+ ; CHECK-LABEL: name: vred_vs2
+ ; CHECK: %x:vr = PseudoVADD_VV_M1 $noreg, $noreg, $noreg, 1, 3 /* e8 */, 0 /* tu, mu */
+ ; CHECK-NEXT: %y:vr = PseudoVREDAND_VS_M1_E8 $noreg, %x, $noreg, 1, 3 /* e8 */, 0 /* tu, mu */
+ %x:vr = PseudoVADD_VV_M1 $noreg, $noreg, $noreg, -1, 3 /* e8 */, 0
+ %y:vr = PseudoVREDAND_VS_M1_E8 $noreg, %x, $noreg, 1, 3 /* e8 */, 0
+...
+---
+name: vred_vs1
+body: |
+ bb.0:
+ ; CHECK-LABEL: name: vred_vs1
+ ; CHECK: %x:vr = PseudoVADD_VV_M1 $noreg, $noreg, $noreg, 1, 3 /* e8 */, 0 /* tu, mu */
+ ; CHECK-NEXT: %y:vr = PseudoVREDAND_VS_M1_E8 $noreg, $noreg, %x, 1, 3 /* e8 */, 0 /* tu, mu */
+ %x:vr = PseudoVADD_VV_M1 $noreg, $noreg, $noreg, -1, 3 /* e8 */, 0
+ %y:vr = PseudoVREDAND_VS_M1_E8 $noreg, $noreg, %x, 1, 3 /* e8 */, 0
+...
diff --git a/llvm/test/CodeGen/RISCV/rvv/vl-opt.mir b/llvm/test/CodeGen/RISCV/rvv/vl-opt.mir
index 010e3ca642269b..64a6a09fb6e8dd 100644
--- a/llvm/test/CodeGen/RISCV/rvv/vl-opt.mir
+++ b/llvm/test/CodeGen/RISCV/rvv/vl-opt.mir
@@ -33,3 +33,15 @@ body: |
%y:vr = PseudoVREDSUM_VS_M1_E64 $noreg, %x, $noreg, -1, 6 /* e64 */, 0 /* tu, mu */
%z:vr = PseudoVADD_VV_M1 $noreg, %x, $noreg, %vl, 5 /* e32 */, 0 /* tu, mu */
...
+---
+name: vred_other_user_is_vl0
+body: |
+ bb.0:
+ ; CHECK-LABEL: name: vred_other_user_is_vl0
+ ; CHECK: %x:vr = PseudoVADD_VV_M1 $noreg, $noreg, $noreg, -1, 3 /* e8 */, 0 /* tu, mu */
+ ; CHECK-NEXT: %y:vr = PseudoVREDSUM_VS_M1_E8 $noreg, $noreg, %x, 1, 3 /* e8 */, 0 /* tu, mu */
+ ; CHECK-NEXT: %z:vr = PseudoVADD_VV_M1 $noreg, %x, $noreg, 0, 3 /* e8 */, 0 /* tu, mu */
+ %x:vr = PseudoVADD_VV_M1 $noreg, $noreg, $noreg, -1, 3 /* e8 */, 0
+ %y:vr = PseudoVREDSUM_VS_M1_E8 $noreg, $noreg, %x, 1, 3 /* e8 */, 0
+ %z:vr = PseudoVADD_VV_M1 $noreg, %x, $noreg, 0, 3 /* e8 */, 0
+...
>From 48c8d6636ab52a92becd80fe624b23c748d5363a Mon Sep 17 00:00:00 2001
From: Michael Maitland <michaeltmaitland at gmail.com>
Date: Tue, 17 Dec 2024 18:09:51 -0800
Subject: [PATCH 2/3] fixup! add more incompat tests
---
.../test/CodeGen/RISCV/rvv/vl-opt-op-info.mir | 31 +++++++++++++++++++
1 file changed, 31 insertions(+)
diff --git a/llvm/test/CodeGen/RISCV/rvv/vl-opt-op-info.mir b/llvm/test/CodeGen/RISCV/rvv/vl-opt-op-info.mir
index e151d82e4d6217..638c54d4502a2c 100644
--- a/llvm/test/CodeGen/RISCV/rvv/vl-opt-op-info.mir
+++ b/llvm/test/CodeGen/RISCV/rvv/vl-opt-op-info.mir
@@ -912,3 +912,34 @@ body: |
%x:vr = PseudoVADD_VV_M1 $noreg, $noreg, $noreg, -1, 3 /* e8 */, 0
%y:vr = PseudoVREDAND_VS_M1_E8 $noreg, $noreg, %x, 1, 3 /* e8 */, 0
...
+---
+name: vred_vs1_vs2
+body: |
+ bb.0:
+ ; CHECK-LABEL: name: vred_vs1_vs2
+ ; CHECK: %x:vr = PseudoVADD_VV_M1 $noreg, $noreg, $noreg, -1, 3 /* e8 */, 0 /* tu, mu */
+ ; CHECK-NEXT: %y:vr = PseudoVREDAND_VS_M1_E8 $noreg, %x, %x, 1, 3 /* e8 */, 0 /* tu, mu */
+ %x:vr = PseudoVADD_VV_M1 $noreg, $noreg, $noreg, -1, 3 /* e8 */, 0
+ %y:vr = PseudoVREDAND_VS_M1_E8 $noreg, %x, %x, 1, 3 /* e8 */, 0
+...
+---
+name: vred_vs1_vs2_incompatible_eew
+body: |
+ bb.0:
+ ; CHECK-LABEL: name: vred_vs1_vs2_incompatible_eew
+ ; CHECK: %x:vr = PseudoVADD_VV_M1 $noreg, $noreg, $noreg, -1, 3 /* e8 */, 0 /* tu, mu */
+ ; CHECK-NEXT: %y:vr = PseudoVREDAND_VS_M1_E8 $noreg, %x, %x, 1, 4 /* e16 */, 0 /* tu, mu */
+ %x:vr = PseudoVADD_VV_M1 $noreg, $noreg, $noreg, -1, 3 /* e8 */, 0
+ %y:vr = PseudoVREDAND_VS_M1_E8 $noreg, %x, %x, 1, 4 /* e16 */, 0
+...
+---
+name: vred_vs1_vs2_incomaptible_emul
+body: |
+ bb.0:
+ ; CHECK-LABEL: name: vred_vs1_vs2_incomaptible_emul
+ ; CHECK: %x:vr = PseudoVADD_VV_M1 $noreg, $noreg, $noreg, -1, 3 /* e8 */, 0 /* tu, mu */
+ ; CHECK-NEXT: %y:vr = PseudoVREDAND_VS_MF2_E8 $noreg, %x, %x, 1, 3 /* e8 */, 0 /* tu, mu */
+ %x:vr = PseudoVADD_VV_M1 $noreg, $noreg, $noreg, -1, 3 /* e8 */, 0
+ %y:vr = PseudoVREDAND_VS_MF2_E8 $noreg, %x, %x, 1, 3 /* e8 */, 0
+...
+
>From a7c71ea6297a46db7f4507cd1983626296f3e446 Mon Sep 17 00:00:00 2001
From: Michael Maitland <michaeltmaitland at gmail.com>
Date: Tue, 17 Dec 2024 18:17:35 -0800
Subject: [PATCH 3/3] fixup! do not else after continue/break
---
llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp b/llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp
index fb020e361b4cee..1b838011cf7ef9 100644
--- a/llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp
+++ b/llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp
@@ -920,10 +920,12 @@ bool RISCVVLOptimizer::checkUsers(const MachineOperand *&CommonVL,
if (!CommonVL) {
CommonVL = &VLOp;
continue;
- } else if (!CommonVL->isIdenticalTo(VLOp)) {
+ }
+ if (!CommonVL->isIdenticalTo(VLOp)) {
CanReduceVL = false;
break;
}
+ continue;
}
}
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