compiler, internal/abi: implement FuncPCABI0, FuncPCABIInternal

The Go 1.18 standard library uses an internal/abi package with two
functions that are implemented in the compiler. This patch implements
them in the gofrontend, to support the upcoming update to 1.18.

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/383514

3 files changed, 42 insertions, 5 deletions

diff --git a/libgo/go/internal/abi/abi.go b/libgo/go/internal/abi/abi.go
new file mode 100644
index 00000000000..c4a108847ca
--- /dev/null
+++ b/libgo/go/internal/abi/abi.go
@@ -0,0 +1,35 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package abi
+
+// FuncPC* intrinsics.
+//
+// CAREFUL: In programs with plugins, FuncPC* can return different values
+// for the same function (because there are actually multiple copies of
+// the same function in the address space). To be safe, don't use the
+// results of this function in any == expression. It is only safe to
+// use the result as an address at which to start executing code.
+
+// FuncPCABI0 returns the entry PC of the function f, which must be a
+// direct reference of a function defined as ABI0. Otherwise it is a
+// compile-time error.
+//
+// Implemented as a compile intrinsic.
+func FuncPCABI0(f any) uintptr {
+        // The compiler should remove all calls.
+        panic("FuncPCABI0")
+}
+
+// FuncPCABIInternal returns the entry PC of the function f. If f is a
+// direct reference of a function, it must be defined as ABIInternal.
+// Otherwise it is a compile-time error. If f is not a direct reference
+// of a defined function, it assumes that f is a func value. Otherwise
+// the behavior is undefined.
+//
+// Implemented as a compile intrinsic.
+func FuncPCABIInternal(f any) uintptr {
+        // The compiler should remove all calls.
+        panic("FuncPCABIInternal")
+}
diff --git a/libgo/go/runtime/proc.go b/libgo/go/runtime/proc.go
index 05342905ff1..343f13b40f0 100644
--- a/libgo/go/runtime/proc.go
+++ b/libgo/go/runtime/proc.go
@@ -5,6 +5,7 @@
 package runtime
 
 import (
+        "internal/abi"
         "internal/cpu"
         "runtime/internal/atomic"
         "runtime/internal/sys"
@@ -4243,11 +4244,11 @@ func _GC()                        { _GC() }
 func _LostSIGPROFDuringAtomic64() { _LostSIGPROFDuringAtomic64() }
 func _VDSO()                      { _VDSO() }
 
-var _SystemPC = funcPC(_System)
-var _ExternalCodePC = funcPC(_ExternalCode)
-var _LostExternalCodePC = funcPC(_LostExternalCode)
-var _GCPC = funcPC(_GC)
-var _LostSIGPROFDuringAtomic64PC = funcPC(_LostSIGPROFDuringAtomic64)
+var _SystemPC = abi.FuncPCABIInternal(_System)
+var _ExternalCodePC = abi.FuncPCABIInternal(_ExternalCode)
+var _LostExternalCodePC = abi.FuncPCABIInternal(_LostExternalCode)
+var _GCPC = abi.FuncPCABIInternal(_GC)
+var _LostSIGPROFDuringAtomic64PC = abi.FuncPCABIInternal(_LostSIGPROFDuringAtomic64)
 
 // Called if we receive a SIGPROF signal.
 // Called by the signal handler, may run during STW.
diff --git a/libgo/libgo-packages.txt b/libgo/libgo-packages.txt
index 4fc8c843f02..f3097dc0a6a 100644
--- a/libgo/libgo-packages.txt
+++ b/libgo/libgo-packages.txt
@@ -113,6 +113,7 @@ image/internal/imageutil
 image/jpeg
 image/png
 index/suffixarray
+internal/abi
 internal/buildcfg
 internal/bytealg
 internal/cfg