[llvm] [ARM]: codegen `llvm.roundeven.v*` (PR #141786)

Folkert de Vries via llvm-commits llvm-commits at lists.llvm.org
Thu May 29 11:05:30 PDT 2025


https://github.com/folkertdev updated https://github.com/llvm/llvm-project/pull/141786

>From f473a87480e3556d1aabd9bcd713d595c08fd7f4 Mon Sep 17 00:00:00 2001
From: Folkert de Vries <folkert at folkertdev.nl>
Date: Wed, 28 May 2025 16:54:41 +0200
Subject: [PATCH] [ARM]: codegen `llvm.roundeven.v*`

---
 llvm/lib/Target/ARM/ARMISelLowering.cpp       |   6 +
 llvm/lib/Target/ARM/ARMInstrVFP.td            |   8 +-
 llvm/test/CodeGen/ARM/arm32-rounding.ll       |  18 +++
 llvm/test/CodeGen/ARM/vrint.ll                | 108 ++++++++++++++++++
 llvm/test/CodeGen/Thumb2/bf16-instructions.ll |   2 +-
 5 files changed, 140 insertions(+), 2 deletions(-)

diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index afbf1b4c55e70..8b65d3eeafa06 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -905,6 +905,7 @@ ARMTargetLowering::ARMTargetLowering(const TargetMachine &TM,
     setOperationAction(ISD::FCEIL, MVT::v2f64, Expand);
     setOperationAction(ISD::FTRUNC, MVT::v2f64, Expand);
     setOperationAction(ISD::FRINT, MVT::v2f64, Expand);
+    setOperationAction(ISD::FROUNDEVEN, MVT::v2f64, Expand);
     setOperationAction(ISD::FNEARBYINT, MVT::v2f64, Expand);
     setOperationAction(ISD::FFLOOR, MVT::v2f64, Expand);
     setOperationAction(ISD::FMA, MVT::v2f64, Expand);
@@ -927,6 +928,7 @@ ARMTargetLowering::ARMTargetLowering(const TargetMachine &TM,
     setOperationAction(ISD::FCEIL, MVT::v4f32, Expand);
     setOperationAction(ISD::FTRUNC, MVT::v4f32, Expand);
     setOperationAction(ISD::FRINT, MVT::v4f32, Expand);
+    setOperationAction(ISD::FROUNDEVEN, MVT::v4f32, Expand);
     setOperationAction(ISD::FNEARBYINT, MVT::v4f32, Expand);
     setOperationAction(ISD::FFLOOR, MVT::v4f32, Expand);
 
@@ -945,6 +947,7 @@ ARMTargetLowering::ARMTargetLowering(const TargetMachine &TM,
     setOperationAction(ISD::FCEIL, MVT::v2f32, Expand);
     setOperationAction(ISD::FTRUNC, MVT::v2f32, Expand);
     setOperationAction(ISD::FRINT, MVT::v2f32, Expand);
+    setOperationAction(ISD::FROUNDEVEN, MVT::v2f32, Expand);
     setOperationAction(ISD::FNEARBYINT, MVT::v2f32, Expand);
     setOperationAction(ISD::FFLOOR, MVT::v2f32, Expand);
 
@@ -1087,6 +1090,7 @@ ARMTargetLowering::ARMTargetLowering(const TargetMachine &TM,
     setOperationAction(ISD::FCEIL,      MVT::f64, Expand);
     setOperationAction(ISD::FTRUNC,     MVT::f64, Expand);
     setOperationAction(ISD::FRINT,      MVT::f64, Expand);
+    setOperationAction(ISD::FROUNDEVEN, MVT::f64, Expand);
     setOperationAction(ISD::FNEARBYINT, MVT::f64, Expand);
     setOperationAction(ISD::FFLOOR,     MVT::f64, Expand);
     setOperationAction(ISD::SINT_TO_FP, MVT::i32, Custom);
@@ -1534,6 +1538,7 @@ ARMTargetLowering::ARMTargetLowering(const TargetMachine &TM,
     setOperationAction(ISD::FTRUNC, MVT::f32, Legal);
     setOperationAction(ISD::FNEARBYINT, MVT::f32, Legal);
     setOperationAction(ISD::FRINT, MVT::f32, Legal);
+    setOperationAction(ISD::FROUNDEVEN, MVT::f32, Legal);
     setOperationAction(ISD::FMINNUM, MVT::f32, Legal);
     setOperationAction(ISD::FMAXNUM, MVT::f32, Legal);
     if (Subtarget->hasNEON()) {
@@ -1550,6 +1555,7 @@ ARMTargetLowering::ARMTargetLowering(const TargetMachine &TM,
       setOperationAction(ISD::FTRUNC, MVT::f64, Legal);
       setOperationAction(ISD::FNEARBYINT, MVT::f64, Legal);
       setOperationAction(ISD::FRINT, MVT::f64, Legal);
+      setOperationAction(ISD::FROUNDEVEN, MVT::f64, Legal);
       setOperationAction(ISD::FMINNUM, MVT::f64, Legal);
       setOperationAction(ISD::FMAXNUM, MVT::f64, Legal);
     }
diff --git a/llvm/lib/Target/ARM/ARMInstrVFP.td b/llvm/lib/Target/ARM/ARMInstrVFP.td
index 2ee2cb2fda4a0..1fe14971fb7e8 100644
--- a/llvm/lib/Target/ARM/ARMInstrVFP.td
+++ b/llvm/lib/Target/ARM/ARMInstrVFP.td
@@ -1135,8 +1135,14 @@ multiclass vrint_inst_anpm<string opc, bits<2> rm,
         Requires<[HasFPARMv8,HasDPVFP]>;
 }
 
+// Match either any_froundeven or int_arm_neon_vrintn
+def vfrinn_or_froundeven : PatFrags<(ops node:$src), [
+  (int_arm_neon_vrintn node:$src),
+  (any_froundeven node:$src)
+]>;
+
 defm VRINTA : vrint_inst_anpm<"a", 0b00, fround>;
-defm VRINTN : vrint_inst_anpm<"n", 0b01, int_arm_neon_vrintn>;
+defm VRINTN : vrint_inst_anpm<"n", 0b01, vfrinn_or_froundeven>;
 defm VRINTP : vrint_inst_anpm<"p", 0b10, fceil>;
 defm VRINTM : vrint_inst_anpm<"m", 0b11, ffloor>;
 
diff --git a/llvm/test/CodeGen/ARM/arm32-rounding.ll b/llvm/test/CodeGen/ARM/arm32-rounding.ll
index b0a9f54e42404..cc5b5612f49bb 100644
--- a/llvm/test/CodeGen/ARM/arm32-rounding.ll
+++ b/llvm/test/CodeGen/ARM/arm32-rounding.ll
@@ -104,6 +104,22 @@ entry:
   ret double %call
 }
 
+; CHECK-LABEL: test13
+; CHECK: vrintn.f32
+define float @test13(float %a) {
+entry:
+  %round = call float @llvm.roundeven.f32(float %a)
+  ret float %round
+}
+
+; CHECK-LABEL: test14
+; CHECK: vrintn.f64
+define double @test14(double %a) {
+entry:
+  %round = call double @llvm.roundeven.f64(double %a)
+  ret double %round
+}
+
 declare float @floorf(float) nounwind readnone
 declare double @floor(double) nounwind readnone
 declare float @ceilf(float) nounwind readnone
@@ -116,3 +132,5 @@ declare float @nearbyintf(float) nounwind readnone
 declare double @nearbyint(double) nounwind readnone
 declare float @rintf(float) nounwind readnone
 declare double @rint(double) nounwind readnone
+declare float @llvm.roundeven.f32(float)
+declare double @llvm.roundeven.f64(double)
diff --git a/llvm/test/CodeGen/ARM/vrint.ll b/llvm/test/CodeGen/ARM/vrint.ll
index 908be673295ff..40f806ba55d36 100644
--- a/llvm/test/CodeGen/ARM/vrint.ll
+++ b/llvm/test/CodeGen/ARM/vrint.ll
@@ -1,6 +1,8 @@
 ; RUN: llc -mtriple=armv8 -mattr=+neon %s -o - | FileCheck %s
 
 declare float @llvm.arm.neon.vrintn.f32(float) nounwind readnone
+declare <2 x float> @llvm.arm.neon.vrintn.v2f32(<2 x float>) nounwind readnone
+declare <4 x float> @llvm.arm.neon.vrintn.v4f32(<4 x float>) nounwind readnone
 
 ; CHECK-LABEL: vrintn_f32:
 ; CHECK: vrintn.f32
@@ -9,3 +11,109 @@ define float @vrintn_f32(ptr %A) nounwind {
   %tmp2 = call float @llvm.arm.neon.vrintn.f32(float %tmp1)
   ret float %tmp2
 }
+
+define <2 x float> @frintn_2s(<2 x float> %A) nounwind {
+; CHECK-LABEL: frintn_2s:
+; CHECK:       @ %bb.0:
+; CHECK-NEXT:    vmov d16, r0, r1
+; CHECK-NEXT:    vrintn.f32 d16, d16
+; CHECK-NEXT:    vmov r0, r1, d16
+; CHECK-NEXT:    bx lr
+	%tmp3 = call <2 x float> @llvm.arm.neon.vrintn.v2f32(<2 x float> %A)
+	ret <2 x float> %tmp3
+}
+
+define <4 x float> @frintn_4s(<4 x float> %A) nounwind {
+; CHECK-LABEL: frintn_4s:
+; CHECK:       @ %bb.0:
+; CHECK-NEXT:    vmov d17, r2, r3
+; CHECK-NEXT:    vmov d16, r0, r1
+; CHECK-NEXT:    vrintn.f32 q8, q8
+; CHECK-NEXT:    vmov r0, r1, d16
+; CHECK-NEXT:    vmov r2, r3, d17
+; CHECK-NEXT:    bx lr
+	%tmp3 = call <4 x float> @llvm.arm.neon.vrintn.v4f32(<4 x float> %A)
+	ret <4 x float> %tmp3
+}
+
+define <4 x half> @roundeven_4h(<4 x half> %A) nounwind {
+; CHECK-LABEL: roundeven_4h:
+; CHECK:       @ %bb.0:
+; CHECK-NEXT:    vmov s0, r3
+; CHECK-NEXT:    vcvtb.f32.f16 s0, s0
+; CHECK-NEXT:    vmov s2, r2
+; CHECK-NEXT:    vrintn.f32 s0, s0
+; CHECK-NEXT:    vcvtb.f32.f16 s2, s2
+; CHECK-NEXT:    vrintn.f32 s2, s2
+; CHECK-NEXT:    vcvtb.f16.f32 s0, s0
+; CHECK-NEXT:    vcvtb.f16.f32 s2, s2
+; CHECK-NEXT:    vmov r2, s0
+; CHECK-NEXT:    vmov s0, r1
+; CHECK-NEXT:    vmov r3, s2
+; CHECK-NEXT:    vcvtb.f32.f16 s0, s0
+; CHECK-NEXT:    vmov s2, r0
+; CHECK-NEXT:    vrintn.f32 s0, s0
+; CHECK-NEXT:    vcvtb.f32.f16 s2, s2
+; CHECK-NEXT:    vcvtb.f16.f32 s0, s0
+; CHECK-NEXT:    vrintn.f32 s2, s2
+; CHECK-NEXT:    vmov r0, s0
+; CHECK-NEXT:    vcvtb.f16.f32 s2, s2
+; CHECK-NEXT:    vmov r1, s2
+; CHECK-NEXT:    pkhbt r2, r3, r2, lsl #16
+; CHECK-NEXT:    pkhbt r0, r1, r0, lsl #16
+; CHECK-NEXT:    vmov d16, r0, r2
+; CHECK-NEXT:    vmov.u16 r0, d16[0]
+; CHECK-NEXT:    vmov.u16 r1, d16[1]
+; CHECK-NEXT:    vmov.u16 r2, d16[2]
+; CHECK-NEXT:    vmov.u16 r3, d16[3]
+; CHECK-NEXT:    bx lr
+	%tmp3 = call <4 x half> @llvm.roundeven.v4f16(<4 x half> %A)
+	ret <4 x half> %tmp3
+}
+
+define <2 x float> @roundeven_2s(<2 x float> %A) nounwind {
+; CHECK-LABEL: roundeven_2s:
+; CHECK:       @ %bb.0:
+; CHECK-NEXT:    vmov d0, r0, r1
+; CHECK-NEXT:    vrintn.f32 s3, s1
+; CHECK-NEXT:    vrintn.f32 s2, s0
+; CHECK-NEXT:    vmov r0, r1, d1
+; CHECK-NEXT:    bx lr
+	%tmp3 = call <2 x float> @llvm.roundeven.v2f32(<2 x float> %A)
+	ret <2 x float> %tmp3
+}
+
+define <4 x float> @roundeven_4s(<4 x float> %A) nounwind {
+; CHECK-LABEL: roundeven_4s:
+; CHECK:       @ %bb.0:
+; CHECK-NEXT:    vmov d1, r2, r3
+; CHECK-NEXT:    vmov d0, r0, r1
+; CHECK-NEXT:    vrintn.f32 s7, s3
+; CHECK-NEXT:    vrintn.f32 s6, s2
+; CHECK-NEXT:    vrintn.f32 s5, s1
+; CHECK-NEXT:    vrintn.f32 s4, s0
+; CHECK-NEXT:    vmov r2, r3, d3
+; CHECK-NEXT:    vmov r0, r1, d2
+; CHECK-NEXT:    bx lr
+	%tmp3 = call <4 x float> @llvm.roundeven.v4f32(<4 x float> %A)
+	ret <4 x float> %tmp3
+}
+
+define <2 x double> @roundeven_2d(<2 x double> %A) nounwind {
+; CHECK-LABEL: roundeven_2d:
+; CHECK:       @ %bb.0:
+; CHECK-NEXT:    vmov d16, r2, r3
+; CHECK-NEXT:    vmov d17, r0, r1
+; CHECK-NEXT:    vrintn.f64 d16, d16
+; CHECK-NEXT:    vrintn.f64 d17, d17
+; CHECK-NEXT:    vmov r2, r3, d16
+; CHECK-NEXT:    vmov r0, r1, d17
+; CHECK-NEXT:    bx lr
+	%tmp3 = call <2 x double> @llvm.roundeven.v2f64(<2 x double> %A)
+	ret <2 x double> %tmp3
+}
+
+declare <4 x half> @llvm.roundeven.v4f16(<4 x half>) nounwind readnone
+declare <2 x float> @llvm.roundeven.v2f32(<2 x float>) nounwind readnone
+declare <4 x float> @llvm.roundeven.v4f32(<4 x float>) nounwind readnone
+declare <2 x double> @llvm.roundeven.v2f64(<2 x double>) nounwind readnone
diff --git a/llvm/test/CodeGen/Thumb2/bf16-instructions.ll b/llvm/test/CodeGen/Thumb2/bf16-instructions.ll
index c93ddca949234..313d237d54b35 100644
--- a/llvm/test/CodeGen/Thumb2/bf16-instructions.ll
+++ b/llvm/test/CodeGen/Thumb2/bf16-instructions.ll
@@ -2373,7 +2373,7 @@ define bfloat @test_roundeven(bfloat %a) {
 ; CHECK-FP-NEXT:    vmov r0, s0
 ; CHECK-FP-NEXT:    lsls r0, r0, #16
 ; CHECK-FP-NEXT:    vmov s0, r0
-; CHECK-FP-NEXT:    bl roundevenf
+; CHECK-FP-NEXT:    vrintn.f32 s0, s0
 ; CHECK-FP-NEXT:    bl __truncsfbf2
 ; CHECK-FP-NEXT:    vmov.f16 r0, s0
 ; CHECK-FP-NEXT:    vmov s0, r0



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