[llvm] 99774ec - [LoongArch] Override cost hooks to expose more DAG combine opportunities (#157824)
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Mon Sep 29 01:02:44 PDT 2025
Author: ZhaoQi
Date: 2025-09-29T08:02:39Z
New Revision: 99774ec661a4487f0c334d8396487359db918cd1
URL: https://github.com/llvm/llvm-project/commit/99774ec661a4487f0c334d8396487359db918cd1
DIFF: https://github.com/llvm/llvm-project/commit/99774ec661a4487f0c334d8396487359db918cd1.diff
LOG: [LoongArch] Override cost hooks to expose more DAG combine opportunities (#157824)
Added:
Modified:
llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp
llvm/lib/Target/LoongArch/LoongArchISelLowering.h
llvm/test/CodeGen/LoongArch/lasx/scalarize-fp.ll
llvm/test/CodeGen/LoongArch/lsx/scalarize-fp.ll
Removed:
################################################################################
diff --git a/llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp b/llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp
index ecd003cae3263..098bcfa67d1d3 100644
--- a/llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp
+++ b/llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp
@@ -9559,3 +9559,20 @@ bool LoongArchTargetLowering::shouldScalarizeBinop(SDValue VecOp) const {
EVT ScalarVT = VecVT.getScalarType();
return isOperationLegalOrCustomOrPromote(Opc, ScalarVT);
}
+
+bool LoongArchTargetLowering::isExtractSubvectorCheap(EVT ResVT, EVT SrcVT,
+ unsigned Index) const {
+ if (!isOperationLegalOrCustom(ISD::EXTRACT_SUBVECTOR, ResVT))
+ return false;
+
+ // Extract a 128-bit subvector from index 0 of a 256-bit vector is free.
+ return Index == 0;
+}
+
+bool LoongArchTargetLowering::isExtractVecEltCheap(EVT VT,
+ unsigned Index) const {
+ EVT EltVT = VT.getScalarType();
+
+ // Extract a scalar FP value from index 0 of a vector is free.
+ return (EltVT == MVT::f32 || EltVT == MVT::f64) && Index == 0;
+}
diff --git a/llvm/lib/Target/LoongArch/LoongArchISelLowering.h b/llvm/lib/Target/LoongArch/LoongArchISelLowering.h
index 3c00296116ac2..9b60a9fd53726 100644
--- a/llvm/lib/Target/LoongArch/LoongArchISelLowering.h
+++ b/llvm/lib/Target/LoongArch/LoongArchISelLowering.h
@@ -338,6 +338,9 @@ class LoongArchTargetLowering : public TargetLowering {
unsigned Depth) const override;
bool shouldScalarizeBinop(SDValue VecOp) const override;
+ bool isExtractSubvectorCheap(EVT ResVT, EVT SrcVT,
+ unsigned Index) const override;
+ bool isExtractVecEltCheap(EVT VT, unsigned Index) const override;
/// Check if a constant splat can be generated using [x]vldi, where imm[12]
/// is 1.
diff --git a/llvm/test/CodeGen/LoongArch/lasx/scalarize-fp.ll b/llvm/test/CodeGen/LoongArch/lasx/scalarize-fp.ll
index c93a6582b9c69..39ac647d6875c 100644
--- a/llvm/test/CodeGen/LoongArch/lasx/scalarize-fp.ll
+++ b/llvm/test/CodeGen/LoongArch/lasx/scalarize-fp.ll
@@ -5,9 +5,8 @@
define <8 x float> @fadd_elt0_v8f32(float %a) nounwind {
; CHECK-LABEL: fadd_elt0_v8f32:
; CHECK: # %bb.0: # %entry
-; CHECK-NEXT: # kill: def $f0 killed $f0 def $xr0
-; CHECK-NEXT: xvldi $xr1, -1424
-; CHECK-NEXT: xvfadd.s $xr0, $xr0, $xr1
+; CHECK-NEXT: vldi $vr1, -1168
+; CHECK-NEXT: fadd.s $fa0, $fa0, $fa1
; CHECK-NEXT: ret
entry:
%b = insertelement <8 x float> poison, float %a, i32 0
@@ -18,9 +17,8 @@ entry:
define <4 x double> @fadd_elt0_v4f64(double %a) nounwind {
; CHECK-LABEL: fadd_elt0_v4f64:
; CHECK: # %bb.0: # %entry
-; CHECK-NEXT: # kill: def $f0_64 killed $f0_64 def $xr0
-; CHECK-NEXT: xvldi $xr1, -912
-; CHECK-NEXT: xvfadd.d $xr0, $xr0, $xr1
+; CHECK-NEXT: vldi $vr1, -912
+; CHECK-NEXT: fadd.d $fa0, $fa0, $fa1
; CHECK-NEXT: ret
entry:
%b = insertelement <4 x double> poison, double %a, i32 0
@@ -31,11 +29,8 @@ entry:
define <8 x float> @fsub_splat_v8f32(float %a, float %b) nounwind {
; CHECK-LABEL: fsub_splat_v8f32:
; CHECK: # %bb.0: # %entry
-; CHECK-NEXT: # kill: def $f1 killed $f1 def $vr1
-; CHECK-NEXT: # kill: def $f0 killed $f0 def $vr0
-; CHECK-NEXT: vfsub.s $vr0, $vr0, $vr1
-; CHECK-NEXT: xvpermi.d $xr0, $xr0, 68
-; CHECK-NEXT: xvrepl128vei.w $xr0, $xr0, 0
+; CHECK-NEXT: fsub.s $fa0, $fa0, $fa1
+; CHECK-NEXT: xvreplve0.w $xr0, $xr0
; CHECK-NEXT: ret
entry:
%insa = insertelement <8 x float> poison, float %a, i32 0
@@ -49,10 +44,9 @@ entry:
define <4 x double> @fsub_splat_v4f64(double %a) nounwind {
; CHECK-LABEL: fsub_splat_v4f64:
; CHECK: # %bb.0: # %entry
-; CHECK-NEXT: # kill: def $f0_64 killed $f0_64 def $xr0
-; CHECK-NEXT: xvldi $xr1, -784
-; CHECK-NEXT: xvfadd.d $xr0, $xr0, $xr1
-; CHECK-NEXT: xvpermi.d $xr0, $xr0, 0
+; CHECK-NEXT: vldi $vr1, -784
+; CHECK-NEXT: fadd.d $fa0, $fa0, $fa1
+; CHECK-NEXT: xvreplve0.d $xr0, $xr0
; CHECK-NEXT: ret
entry:
%insa = insertelement <4 x double> poison, double %a, i32 0
diff --git a/llvm/test/CodeGen/LoongArch/lsx/scalarize-fp.ll b/llvm/test/CodeGen/LoongArch/lsx/scalarize-fp.ll
index cc2d3d818b412..b651f11596c82 100644
--- a/llvm/test/CodeGen/LoongArch/lsx/scalarize-fp.ll
+++ b/llvm/test/CodeGen/LoongArch/lsx/scalarize-fp.ll
@@ -5,9 +5,8 @@
define <4 x float> @fadd_elt0_v4f32(float %a) nounwind {
; CHECK-LABEL: fadd_elt0_v4f32:
; CHECK: # %bb.0: # %entry
-; CHECK-NEXT: # kill: def $f0 killed $f0 def $vr0
-; CHECK-NEXT: vldi $vr1, -1424
-; CHECK-NEXT: vfadd.s $vr0, $vr0, $vr1
+; CHECK-NEXT: vldi $vr1, -1168
+; CHECK-NEXT: fadd.s $fa0, $fa0, $fa1
; CHECK-NEXT: ret
entry:
%b = insertelement <4 x float> poison, float %a, i32 0
@@ -18,9 +17,8 @@ entry:
define <2 x double> @fadd_elt0_v2f64(double %a) nounwind {
; CHECK-LABEL: fadd_elt0_v2f64:
; CHECK: # %bb.0: # %entry
-; CHECK-NEXT: # kill: def $f0_64 killed $f0_64 def $vr0
; CHECK-NEXT: vldi $vr1, -912
-; CHECK-NEXT: vfadd.d $vr0, $vr0, $vr1
+; CHECK-NEXT: fadd.d $fa0, $fa0, $fa1
; CHECK-NEXT: ret
entry:
%b = insertelement <2 x double> poison, double %a, i32 0
@@ -31,9 +29,8 @@ entry:
define <4 x float> @fsub_splat_v4f32(float %b) nounwind {
; CHECK-LABEL: fsub_splat_v4f32:
; CHECK: # %bb.0: # %entry
-; CHECK-NEXT: # kill: def $f0 killed $f0 def $vr0
-; CHECK-NEXT: vldi $vr1, -1424
-; CHECK-NEXT: vfsub.s $vr0, $vr1, $vr0
+; CHECK-NEXT: vldi $vr1, -1168
+; CHECK-NEXT: fsub.s $fa0, $fa1, $fa0
; CHECK-NEXT: vreplvei.w $vr0, $vr0, 0
; CHECK-NEXT: ret
entry:
@@ -48,9 +45,7 @@ entry:
define <2 x double> @fsub_splat_v2f64(double %a, double %b) nounwind {
; CHECK-LABEL: fsub_splat_v2f64:
; CHECK: # %bb.0: # %entry
-; CHECK-NEXT: # kill: def $f1_64 killed $f1_64 def $vr1
-; CHECK-NEXT: # kill: def $f0_64 killed $f0_64 def $vr0
-; CHECK-NEXT: vfsub.d $vr0, $vr0, $vr1
+; CHECK-NEXT: fsub.d $fa0, $fa0, $fa1
; CHECK-NEXT: vreplvei.d $vr0, $vr0, 0
; CHECK-NEXT: ret
entry:
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