[llvm-branch-commits] [llvm] release/20.x: [AArch64] Fix SVE scalar fcopysign lowering without neon. (#129787) (PR #129997)

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Wed Mar 5 22:48:18 PST 2025


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-aarch64

Author: None (llvmbot)

<details>
<summary>Changes</summary>

Backport 4c2d1b4c53de d4ab3df320f9

Requested by: @<!-- -->davemgreen

---
Full diff: https://github.com/llvm/llvm-project/pull/129997.diff


2 Files Affected:

- (modified) llvm/lib/Target/AArch64/AArch64ISelLowering.cpp (+19) 
- (modified) llvm/test/CodeGen/AArch64/sve-streaming-mode-fixed-length-fcopysign.ll (+199) 


``````````diff
diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
index b5cca88b6b511..62a26b0aef187 100644
--- a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -10681,6 +10681,25 @@ SDValue AArch64TargetLowering::LowerFCOPYSIGN(SDValue Op,
     return convertFromScalableVector(DAG, VT, Res);
   }
 
+  // With SVE, but without Neon, extend the scalars to scalable vectors and use
+  // a SVE FCOPYSIGN.
+  if (!VT.isVector() && !Subtarget->isNeonAvailable() &&
+      Subtarget->isSVEorStreamingSVEAvailable()) {
+    if (VT != MVT::f16 && VT != MVT::f32 && VT != MVT::f64)
+      return SDValue();
+    EVT SVT = getPackedSVEVectorVT(VT);
+
+    SDValue Ins1 =
+        DAG.getNode(ISD::INSERT_VECTOR_ELT, DL, SVT, DAG.getUNDEF(SVT), In1,
+                    DAG.getConstant(0, DL, MVT::i64));
+    SDValue Ins2 =
+        DAG.getNode(ISD::INSERT_VECTOR_ELT, DL, SVT, DAG.getUNDEF(SVT), In2,
+                    DAG.getConstant(0, DL, MVT::i64));
+    SDValue FCS = DAG.getNode(ISD::FCOPYSIGN, DL, SVT, Ins1, Ins2);
+    return DAG.getNode(ISD::EXTRACT_VECTOR_ELT, DL, VT, FCS,
+                       DAG.getConstant(0, DL, MVT::i64));
+  }
+
   auto BitCast = [this](EVT VT, SDValue Op, SelectionDAG &DAG) {
     if (VT.isScalableVector())
       return getSVESafeBitCast(VT, Op, DAG);
diff --git a/llvm/test/CodeGen/AArch64/sve-streaming-mode-fixed-length-fcopysign.ll b/llvm/test/CodeGen/AArch64/sve-streaming-mode-fixed-length-fcopysign.ll
index 2282e74af5d00..79921e25caf53 100644
--- a/llvm/test/CodeGen/AArch64/sve-streaming-mode-fixed-length-fcopysign.ll
+++ b/llvm/test/CodeGen/AArch64/sve-streaming-mode-fixed-length-fcopysign.ll
@@ -8,6 +8,205 @@ target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128"
 
 target triple = "aarch64-unknown-linux-gnu"
 
+define void @test_copysign_f16(ptr %ap, ptr %bp) {
+; SVE-LABEL: test_copysign_f16:
+; SVE:       // %bb.0:
+; SVE-NEXT:    ldr h0, [x1]
+; SVE-NEXT:    ldr h1, [x0]
+; SVE-NEXT:    and z0.h, z0.h, #0x8000
+; SVE-NEXT:    and z1.h, z1.h, #0x7fff
+; SVE-NEXT:    orr z0.d, z1.d, z0.d
+; SVE-NEXT:    str h0, [x0]
+; SVE-NEXT:    ret
+;
+; SVE2-LABEL: test_copysign_f16:
+; SVE2:       // %bb.0:
+; SVE2-NEXT:    mov z0.h, #32767 // =0x7fff
+; SVE2-NEXT:    ldr h1, [x1]
+; SVE2-NEXT:    ldr h2, [x0]
+; SVE2-NEXT:    bsl z2.d, z2.d, z1.d, z0.d
+; SVE2-NEXT:    str h2, [x0]
+; SVE2-NEXT:    ret
+;
+; NONEON-NOSVE-LABEL: test_copysign_f16:
+; NONEON-NOSVE:       // %bb.0:
+; NONEON-NOSVE-NEXT:    sub sp, sp, #16
+; NONEON-NOSVE-NEXT:    .cfi_def_cfa_offset 16
+; NONEON-NOSVE-NEXT:    ldr h0, [x0]
+; NONEON-NOSVE-NEXT:    ldr h1, [x1]
+; NONEON-NOSVE-NEXT:    fcvt s0, h0
+; NONEON-NOSVE-NEXT:    str h1, [sp, #12]
+; NONEON-NOSVE-NEXT:    ldrb w8, [sp, #13]
+; NONEON-NOSVE-NEXT:    tst w8, #0x80
+; NONEON-NOSVE-NEXT:    fabs s0, s0
+; NONEON-NOSVE-NEXT:    fneg s1, s0
+; NONEON-NOSVE-NEXT:    fcsel s0, s1, s0, ne
+; NONEON-NOSVE-NEXT:    fcvt h0, s0
+; NONEON-NOSVE-NEXT:    str h0, [x0]
+; NONEON-NOSVE-NEXT:    add sp, sp, #16
+; NONEON-NOSVE-NEXT:    ret
+  %a = load half, ptr %ap
+  %b = load half, ptr %bp
+  %r = call half @llvm.copysign.f16(half %a, half %b)
+  store half %r, ptr %ap
+  ret void
+}
+
+define void @test_copysign_bf16(ptr %ap, ptr %bp) {
+; SVE-LABEL: test_copysign_bf16:
+; SVE:       // %bb.0:
+; SVE-NEXT:    sub sp, sp, #16
+; SVE-NEXT:    .cfi_def_cfa_offset 16
+; SVE-NEXT:    ldr h0, [x0]
+; SVE-NEXT:    ldr h1, [x1]
+; SVE-NEXT:    fmov w8, s0
+; SVE-NEXT:    str h1, [sp, #12]
+; SVE-NEXT:    ldrb w9, [sp, #13]
+; SVE-NEXT:    and w8, w8, #0x7fff
+; SVE-NEXT:    tst w9, #0x80
+; SVE-NEXT:    fmov s0, w8
+; SVE-NEXT:    eor w8, w8, #0x8000
+; SVE-NEXT:    fmov s1, w8
+; SVE-NEXT:    fcsel h0, h1, h0, ne
+; SVE-NEXT:    str h0, [x0]
+; SVE-NEXT:    add sp, sp, #16
+; SVE-NEXT:    ret
+;
+; SVE2-LABEL: test_copysign_bf16:
+; SVE2:       // %bb.0:
+; SVE2-NEXT:    sub sp, sp, #16
+; SVE2-NEXT:    .cfi_def_cfa_offset 16
+; SVE2-NEXT:    ldr h0, [x0]
+; SVE2-NEXT:    ldr h1, [x1]
+; SVE2-NEXT:    fmov w8, s0
+; SVE2-NEXT:    str h1, [sp, #12]
+; SVE2-NEXT:    ldrb w9, [sp, #13]
+; SVE2-NEXT:    and w8, w8, #0x7fff
+; SVE2-NEXT:    tst w9, #0x80
+; SVE2-NEXT:    fmov s0, w8
+; SVE2-NEXT:    eor w8, w8, #0x8000
+; SVE2-NEXT:    fmov s1, w8
+; SVE2-NEXT:    fcsel h0, h1, h0, ne
+; SVE2-NEXT:    str h0, [x0]
+; SVE2-NEXT:    add sp, sp, #16
+; SVE2-NEXT:    ret
+;
+; NONEON-NOSVE-LABEL: test_copysign_bf16:
+; NONEON-NOSVE:       // %bb.0:
+; NONEON-NOSVE-NEXT:    sub sp, sp, #80
+; NONEON-NOSVE-NEXT:    .cfi_def_cfa_offset 80
+; NONEON-NOSVE-NEXT:    ldr h0, [x0]
+; NONEON-NOSVE-NEXT:    ldr h1, [x1]
+; NONEON-NOSVE-NEXT:    str h0, [sp, #40]
+; NONEON-NOSVE-NEXT:    ldr d0, [sp, #40]
+; NONEON-NOSVE-NEXT:    str h1, [sp, #76]
+; NONEON-NOSVE-NEXT:    ushll v0.4s, v0.4h, #0
+; NONEON-NOSVE-NEXT:    str q0, [sp]
+; NONEON-NOSVE-NEXT:    ldr w8, [sp, #12]
+; NONEON-NOSVE-NEXT:    lsl w9, w8, #16
+; NONEON-NOSVE-NEXT:    ldr w8, [sp, #8]
+; NONEON-NOSVE-NEXT:    lsl w8, w8, #16
+; NONEON-NOSVE-NEXT:    stp w8, w9, [sp, #24]
+; NONEON-NOSVE-NEXT:    ldr w8, [sp, #4]
+; NONEON-NOSVE-NEXT:    lsl w9, w8, #16
+; NONEON-NOSVE-NEXT:    ldr w8, [sp]
+; NONEON-NOSVE-NEXT:    lsl w8, w8, #16
+; NONEON-NOSVE-NEXT:    stp w8, w9, [sp, #16]
+; NONEON-NOSVE-NEXT:    ldrb w8, [sp, #77]
+; NONEON-NOSVE-NEXT:    ldr q0, [sp, #16]
+; NONEON-NOSVE-NEXT:    tst w8, #0x80
+; NONEON-NOSVE-NEXT:    str q0, [sp, #48]
+; NONEON-NOSVE-NEXT:    ldr s0, [sp, #48]
+; NONEON-NOSVE-NEXT:    fabs s0, s0
+; NONEON-NOSVE-NEXT:    fneg s1, s0
+; NONEON-NOSVE-NEXT:    fcsel s0, s1, s0, ne
+; NONEON-NOSVE-NEXT:    fmov w8, s0
+; NONEON-NOSVE-NEXT:    lsr w8, w8, #16
+; NONEON-NOSVE-NEXT:    fmov s0, w8
+; NONEON-NOSVE-NEXT:    str h0, [x0]
+; NONEON-NOSVE-NEXT:    add sp, sp, #80
+; NONEON-NOSVE-NEXT:    ret
+  %a = load bfloat, ptr %ap
+  %b = load bfloat, ptr %bp
+  %r = call bfloat @llvm.copysign.bf16(bfloat %a, bfloat %b)
+  store bfloat %r, ptr %ap
+  ret void
+}
+
+define void @test_copysign_f32(ptr %ap, ptr %bp) {
+; SVE-LABEL: test_copysign_f32:
+; SVE:       // %bb.0:
+; SVE-NEXT:    ldr s0, [x1]
+; SVE-NEXT:    ldr s1, [x0]
+; SVE-NEXT:    and z0.s, z0.s, #0x80000000
+; SVE-NEXT:    and z1.s, z1.s, #0x7fffffff
+; SVE-NEXT:    orr z0.d, z1.d, z0.d
+; SVE-NEXT:    str s0, [x0]
+; SVE-NEXT:    ret
+;
+; SVE2-LABEL: test_copysign_f32:
+; SVE2:       // %bb.0:
+; SVE2-NEXT:    mov z0.s, #0x7fffffff
+; SVE2-NEXT:    ldr s1, [x1]
+; SVE2-NEXT:    ldr s2, [x0]
+; SVE2-NEXT:    bsl z2.d, z2.d, z1.d, z0.d
+; SVE2-NEXT:    str s2, [x0]
+; SVE2-NEXT:    ret
+;
+; NONEON-NOSVE-LABEL: test_copysign_f32:
+; NONEON-NOSVE:       // %bb.0:
+; NONEON-NOSVE-NEXT:    ldr s0, [x0]
+; NONEON-NOSVE-NEXT:    ldr w8, [x1]
+; NONEON-NOSVE-NEXT:    fabs s0, s0
+; NONEON-NOSVE-NEXT:    tst w8, #0x80000000
+; NONEON-NOSVE-NEXT:    fneg s1, s0
+; NONEON-NOSVE-NEXT:    fcsel s0, s1, s0, ne
+; NONEON-NOSVE-NEXT:    str s0, [x0]
+; NONEON-NOSVE-NEXT:    ret
+  %a = load float, ptr %ap
+  %b = load float, ptr %bp
+  %r = call float @llvm.copysign.f32(float %a, float %b)
+  store float %r, ptr %ap
+  ret void
+}
+
+define void @test_copysign_f64(ptr %ap, ptr %bp) {
+; SVE-LABEL: test_copysign_f64:
+; SVE:       // %bb.0:
+; SVE-NEXT:    ldr d0, [x1]
+; SVE-NEXT:    ldr d1, [x0]
+; SVE-NEXT:    and z0.d, z0.d, #0x8000000000000000
+; SVE-NEXT:    and z1.d, z1.d, #0x7fffffffffffffff
+; SVE-NEXT:    orr z0.d, z1.d, z0.d
+; SVE-NEXT:    str d0, [x0]
+; SVE-NEXT:    ret
+;
+; SVE2-LABEL: test_copysign_f64:
+; SVE2:       // %bb.0:
+; SVE2-NEXT:    mov z0.d, #0x7fffffffffffffff
+; SVE2-NEXT:    ldr d1, [x1]
+; SVE2-NEXT:    ldr d2, [x0]
+; SVE2-NEXT:    bsl z2.d, z2.d, z1.d, z0.d
+; SVE2-NEXT:    str d2, [x0]
+; SVE2-NEXT:    ret
+;
+; NONEON-NOSVE-LABEL: test_copysign_f64:
+; NONEON-NOSVE:       // %bb.0:
+; NONEON-NOSVE-NEXT:    ldr d0, [x0]
+; NONEON-NOSVE-NEXT:    ldr x8, [x1]
+; NONEON-NOSVE-NEXT:    fabs d0, d0
+; NONEON-NOSVE-NEXT:    tst x8, #0x8000000000000000
+; NONEON-NOSVE-NEXT:    fneg d1, d0
+; NONEON-NOSVE-NEXT:    fcsel d0, d1, d0, ne
+; NONEON-NOSVE-NEXT:    str d0, [x0]
+; NONEON-NOSVE-NEXT:    ret
+  %a = load double, ptr %ap
+  %b = load double, ptr %bp
+  %r = call double @llvm.copysign.f64(double %a, double %b)
+  store double %r, ptr %ap
+  ret void
+}
+
 ;============ f16
 
 define void @test_copysign_v4f16_v4f16(ptr %ap, ptr %bp) {

``````````

</details>


https://github.com/llvm/llvm-project/pull/129997


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