fix: avoid linking icicle dependent files when tag not provided (#1352)

Co-authored-by: Jeremy Felder <[email protected]>

README.md

@@ -162,9 +162,9 @@ func main() {
 
 ### GPU Support
 
-#### Icicle Library
+#### ICICLE Library
 
-The following schemes and curves support experimental use of Ingonyama's Icicle GPU library for low level zk-SNARK primitives such as MSM, NTT, and polynomial operations:
+The following schemes and curves support experimental use of Ingonyama's ICICLE GPU library for low level zk-SNARK primitives such as MSM, NTT, and polynomial operations:
 
 - [x] [Groth16](https://eprint.iacr.org/2016/260)
 
@@ -184,7 +184,7 @@ You can then toggle on or off icicle acceleration by providing the `WithIcicleAc
     proof, err := groth16.Prove(ccs, pk, secretWitness)
 ```
 
-For more information about prerequisites see the [Icicle repo](https://github.com/ingonyama-zk/icicle).
+For more information about prerequisites see the [ICICLE repo](https://github.com/ingonyama-zk/icicle). **NB! ICICLE CUDA kernels are covered by a special license for now. Follow the instructions to download and set up the kernels.**
 
 ## Citing
 

backend/groth16/bn254/icicle/device.go

@@ -0,0 +1,31 @@
+//go:build icicle
+
+package icicle
+
+import (
+	"fmt"
+	"sync"
+
+	"github.com/consensys/gnark/logger"
+	icicle_runtime "github.com/ingonyama-zk/icicle/v3/wrappers/golang/runtime"
+)
+
+var onceWarmUpDevice sync.Once
+
+func warmUpDevice() {
+	onceWarmUpDevice.Do(func() {
+		log := logger.Logger()
+		err := icicle_runtime.LoadBackendFromEnvOrDefault()
+		if err != icicle_runtime.Success {
+			panic(fmt.Sprintf("ICICLE backend loading error: %s", err.AsString()))
+		}
+		device := icicle_runtime.CreateDevice("CUDA", 0)
+		log.Debug().Int32("id", device.Id).Str("type", device.GetDeviceType()).Msg("ICICLE device created")
+		icicle_runtime.RunOnDevice(&device, func(args ...any) {
+			err := icicle_runtime.WarmUpDevice()
+			if err != icicle_runtime.Success {
+				panic(fmt.Sprintf("ICICLE device warmup error: %s", err.AsString()))
+			}
+		})
+	})
+}

backend/groth16/bn254/icicle/doc.go

@@ -1,2 +1,2 @@
 // Package icicle_bn254 implements ICICLE acceleration for BN254 Groth16 backend.
-package icicle_bn254
+package icicle