[llvm] [RISCV] Sink splatted fpext operands (PR #125800)
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Tue Feb 4 20:49:21 PST 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-backend-risc-v
Author: Luke Lau (lukel97)
<details>
<summary>Changes</summary>
We sink splatted operands in codegenprepare to help match .vx/.vf patterns. This extends it to also splat any fpext so that we can match widening vfwadd.vf/vfwadd.wf patterns too.
Some instructions don't have .wf forms so there's no benefit to sinking the fpext. For simplicity this sinks them anyway and lets earlymachine-licm hoist them back out.
---
Full diff: https://github.com/llvm/llvm-project/pull/125800.diff
2 Files Affected:
- (modified) llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp (+6-1)
- (modified) llvm/test/CodeGen/RISCV/rvv/sink-splat-operands.ll (+149)
``````````diff
diff --git a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
index fa7c7c57be25724..6799130bde130c7 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
@@ -2712,7 +2712,12 @@ bool RISCVTTIImpl::isProfitableToSinkOperands(
return false;
}
- Ops.push_back(&Op->getOperandUse(0));
+ Use *InsertEltUse = &Op->getOperandUse(0);
+ // Sink any fpexts since they might be used in a widening fp pattern.
+ auto *InsertElt = cast<InsertElementInst>(InsertEltUse);
+ if (isa<FPExtInst>(InsertElt->getOperand(1)))
+ Ops.push_back(&InsertElt->getOperandUse(1));
+ Ops.push_back(InsertEltUse);
Ops.push_back(&OpIdx.value());
}
return true;
diff --git a/llvm/test/CodeGen/RISCV/rvv/sink-splat-operands.ll b/llvm/test/CodeGen/RISCV/rvv/sink-splat-operands.ll
index 735621aa4390e39..1948675ae9cf0a7 100644
--- a/llvm/test/CodeGen/RISCV/rvv/sink-splat-operands.ll
+++ b/llvm/test/CodeGen/RISCV/rvv/sink-splat-operands.ll
@@ -5741,3 +5741,152 @@ vector.body:
for.cond.cleanup:
ret void
}
+
+define void @sink_splat_vfwadd_vf(ptr nocapture %a, ptr nocapture %b, float %f) {
+; CHECK-LABEL: sink_splat_vfwadd_vf:
+; CHECK: # %bb.0: # %entry
+; CHECK-NEXT: li a1, 0
+; CHECK-NEXT: li a2, 1020
+; CHECK-NEXT: vsetvli a3, zero, e32, m1, ta, ma
+; CHECK-NEXT: .LBB125_1: # %vector.body
+; CHECK-NEXT: # =>This Inner Loop Header: Depth=1
+; CHECK-NEXT: vl1re32.v v8, (a0)
+; CHECK-NEXT: addi a1, a1, 4
+; CHECK-NEXT: addi a2, a2, -4
+; CHECK-NEXT: vfwadd.vf v10, v8, fa0
+; CHECK-NEXT: vs2r.v v10, (a0)
+; CHECK-NEXT: addi a0, a0, 16
+; CHECK-NEXT: j .LBB125_1
+entry:
+ %f.ext = fpext float %f to double
+ %broadcast.splatinsert = insertelement <vscale x 2 x double> poison, double %f.ext, i32 0
+ %broadcast.splat = shufflevector <vscale x 2 x double> %broadcast.splatinsert, <vscale x 2 x double> poison, <vscale x 2 x i32> zeroinitializer
+ br label %vector.body
+
+vector.body: ; preds = %vector.body, %entry
+ %index = phi i64 [ 0, %entry ], [ %index.next, %vector.body ]
+ %0 = getelementptr float, ptr %a, i64 %index
+ %wide.load = load <vscale x 2 x float>, ptr %0
+ %ext = fpext <vscale x 2 x float> %wide.load to <vscale x 2 x double>
+ %1 = fadd <vscale x 2 x double> %ext, %broadcast.splat
+ %2 = getelementptr double, ptr %b, i64 %index
+ store <vscale x 2 x double> %1, ptr %0
+ %index.next = add i64 %index, 4
+ %3 = icmp eq i64 %index.next, 1024
+ br i1 32, label %for.cond.cleanup, label %vector.body
+
+for.cond.cleanup: ; preds = %vector.body
+ ret void
+}
+
+define void @sink_splat_vfwadd_wf(ptr nocapture %a, ptr nocapture %b, float %f) {
+; CHECK-LABEL: sink_splat_vfwadd_wf:
+; CHECK: # %bb.0: # %entry
+; CHECK-NEXT: li a1, 0
+; CHECK-NEXT: li a2, 1020
+; CHECK-NEXT: vsetvli a3, zero, e32, m1, ta, ma
+; CHECK-NEXT: .LBB126_1: # %vector.body
+; CHECK-NEXT: # =>This Inner Loop Header: Depth=1
+; CHECK-NEXT: vl2re64.v v8, (a0)
+; CHECK-NEXT: addi a1, a1, 4
+; CHECK-NEXT: addi a2, a2, -4
+; CHECK-NEXT: vfwadd.wf v8, v8, fa0
+; CHECK-NEXT: vs2r.v v8, (a0)
+; CHECK-NEXT: addi a0, a0, 32
+; CHECK-NEXT: j .LBB126_1
+entry:
+ %f.ext = fpext float %f to double
+ %broadcast.splatinsert = insertelement <vscale x 2 x double> poison, double %f.ext, i32 0
+ %broadcast.splat = shufflevector <vscale x 2 x double> %broadcast.splatinsert, <vscale x 2 x double> poison, <vscale x 2 x i32> zeroinitializer
+ br label %vector.body
+
+vector.body: ; preds = %vector.body, %entry
+ %index = phi i64 [ 0, %entry ], [ %index.next, %vector.body ]
+ %0 = getelementptr double, ptr %a, i64 %index
+ %wide.load = load <vscale x 2 x double>, ptr %0
+ %1 = fadd <vscale x 2 x double> %wide.load, %broadcast.splat
+ %2 = getelementptr double, ptr %b, i64 %index
+ store <vscale x 2 x double> %1, ptr %0
+ %index.next = add i64 %index, 4
+ %3 = icmp eq i64 %index.next, 1024
+ br i1 32, label %for.cond.cleanup, label %vector.body
+
+for.cond.cleanup: ; preds = %vector.body
+ ret void
+}
+
+define void @sink_splat_vfwmul_vf(ptr nocapture %a, ptr nocapture %b, float %f) {
+; CHECK-LABEL: sink_splat_vfwmul_vf:
+; CHECK: # %bb.0: # %entry
+; CHECK-NEXT: li a1, 0
+; CHECK-NEXT: li a2, 1020
+; CHECK-NEXT: vsetvli a3, zero, e32, m1, ta, ma
+; CHECK-NEXT: .LBB127_1: # %vector.body
+; CHECK-NEXT: # =>This Inner Loop Header: Depth=1
+; CHECK-NEXT: vl1re32.v v8, (a0)
+; CHECK-NEXT: addi a1, a1, 4
+; CHECK-NEXT: addi a2, a2, -4
+; CHECK-NEXT: vfwmul.vf v10, v8, fa0
+; CHECK-NEXT: vs2r.v v10, (a0)
+; CHECK-NEXT: addi a0, a0, 16
+; CHECK-NEXT: j .LBB127_1
+entry:
+ %f.ext = fpext float %f to double
+ %broadcast.splatinsert = insertelement <vscale x 2 x double> poison, double %f.ext, i32 0
+ %broadcast.splat = shufflevector <vscale x 2 x double> %broadcast.splatinsert, <vscale x 2 x double> poison, <vscale x 2 x i32> zeroinitializer
+ br label %vector.body
+
+vector.body: ; preds = %vector.body, %entry
+ %index = phi i64 [ 0, %entry ], [ %index.next, %vector.body ]
+ %0 = getelementptr float, ptr %a, i64 %index
+ %wide.load = load <vscale x 2 x float>, ptr %0
+ %ext = fpext <vscale x 2 x float> %wide.load to <vscale x 2 x double>
+ %1 = fmul <vscale x 2 x double> %ext, %broadcast.splat
+ %2 = getelementptr double, ptr %b, i64 %index
+ store <vscale x 2 x double> %1, ptr %0
+ %index.next = add i64 %index, 4
+ %3 = icmp eq i64 %index.next, 1024
+ br i1 32, label %for.cond.cleanup, label %vector.body
+
+for.cond.cleanup: ; preds = %vector.body
+ ret void
+}
+
+; Even though there's no vfwmul.wf we'll sink the fcvt.d.s. Make sure
+; early-machinelicm undos the sink after isel.
+define void @sink_splat_vfwmul_wf(ptr nocapture %a, ptr nocapture %b, float %f) {
+; CHECK-LABEL: sink_splat_vfwmul_wf:
+; CHECK: # %bb.0: # %entry
+; CHECK-NEXT: li a1, 0
+; CHECK-NEXT: li a2, 1020
+; CHECK-NEXT: fcvt.d.s fa5, fa0
+; CHECK-NEXT: vsetvli a3, zero, e64, m2, ta, ma
+; CHECK-NEXT: .LBB128_1: # %vector.body
+; CHECK-NEXT: # =>This Inner Loop Header: Depth=1
+; CHECK-NEXT: vl2re64.v v8, (a0)
+; CHECK-NEXT: addi a1, a1, 4
+; CHECK-NEXT: addi a2, a2, -4
+; CHECK-NEXT: vfmul.vf v8, v8, fa5
+; CHECK-NEXT: vs2r.v v8, (a0)
+; CHECK-NEXT: addi a0, a0, 16
+; CHECK-NEXT: j .LBB128_1
+entry:
+ %f.ext = fpext float %f to double
+ %broadcast.splatinsert = insertelement <vscale x 2 x double> poison, double %f.ext, i32 0
+ %broadcast.splat = shufflevector <vscale x 2 x double> %broadcast.splatinsert, <vscale x 2 x double> poison, <vscale x 2 x i32> zeroinitializer
+ br label %vector.body
+
+vector.body: ; preds = %vector.body, %entry
+ %index = phi i64 [ 0, %entry ], [ %index.next, %vector.body ]
+ %0 = getelementptr float, ptr %a, i64 %index
+ %wide.load = load <vscale x 2 x double>, ptr %0
+ %1 = fmul <vscale x 2 x double> %wide.load, %broadcast.splat
+ %2 = getelementptr double, ptr %b, i64 %index
+ store <vscale x 2 x double> %1, ptr %0
+ %index.next = add i64 %index, 4
+ %3 = icmp eq i64 %index.next, 1024
+ br i1 32, label %for.cond.cleanup, label %vector.body
+
+for.cond.cleanup: ; preds = %vector.body
+ ret void
+}
``````````
</details>
https://github.com/llvm/llvm-project/pull/125800
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