go/analysis/passes/asmdecl: add support for riscv64

Updates golang/go#27532

Change-Id: I9598b610c0b6710644988e5cea7661b2681a0314
Reviewed-on: https://go-review.googlesource.com/c/tools/+/216337
Reviewed-by: Brad Fitzpatrick <[email protected]>
Run-TryBot: Brad Fitzpatrick <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>

Author: 4a6f656c

Diff for: go/analysis/passes/asmdecl/asmdecl.go

@@ -87,6 +87,7 @@ var (
 	asmArchMips64LE = asmArch{name: "mips64le", bigEndian: false, stack: "R29", lr: true}
 	asmArchPpc64    = asmArch{name: "ppc64", bigEndian: true, stack: "R1", lr: true}
 	asmArchPpc64LE  = asmArch{name: "ppc64le", bigEndian: false, stack: "R1", lr: true}
+	asmArchRISCV64  = asmArch{name: "riscv64", bigEndian: false, stack: "SP", lr: true}
 	asmArchS390X    = asmArch{name: "s390x", bigEndian: true, stack: "R15", lr: true}
 	asmArchWasm     = asmArch{name: "wasm", bigEndian: false, stack: "SP", lr: false}
 
@@ -101,6 +102,7 @@ var (
 		&asmArchMips64LE,
 		&asmArchPpc64,
 		&asmArchPpc64LE,
+		&asmArchRISCV64,
 		&asmArchS390X,
 		&asmArchWasm,
 	}