[dev.typeparams] cmd/compile: simplify interface conversions

Simplify the implementation of interface conversions in the compiler.
Don't pass fields that aren't needed (the data word, usually) to the runtime.

For generics, we need to put a dynamic type in an interface. The new
dataWord function is exactly what we need (the type word will come
from a dictionary).

Change-Id: Iade5de5c174854b65ad248f35c7893c603f7be3d
Reviewed-on: https://go-review.googlesource.com/c/go/+/340029
Trust: Keith Randall <khr@golang.org>
Trust: Dan Scales <danscales@google.com>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Dan Scales <danscales@google.com>

1 files changed, 8 insertions, 11 deletions

diff --git a/src/cmd/compile/internal/typecheck/builtin/runtime.go b/src/cmd/compile/internal/typecheck/builtin/runtime.go
index 2b29ea3c08..605b904288 100644
--- a/src/cmd/compile/internal/typecheck/builtin/runtime.go
+++ b/src/cmd/compile/internal/typecheck/builtin/runtime.go
@@ -84,10 +84,15 @@ func decoderune(string, int) (retv rune, retk int)
 func countrunes(string) int
 
 // Non-empty-interface to non-empty-interface conversion.
-func convI2I(typ *byte, elem any) (ret any)
+func convI2I(typ *byte, itab *uintptr) (ret *uintptr)
 
-// Specialized type-to-interface conversion.
-// These return only a data pointer.
+// Convert non-interface type to the data word of a (empty or nonempty) interface.
+func convT(typ *byte, elem *any) unsafe.Pointer
+
+// Same as convT, for types with no pointers in them.
+func convTnoptr(typ *byte, elem *any) unsafe.Pointer
+
+// Specialized versions of convT for specific types.
 // These functions take concrete types in the runtime. But they may
 // be used for a wider range of types, which have the same memory
 // layout as the parameter type. The compiler converts the
@@ -99,14 +104,6 @@ func convT64(val uint64) unsafe.Pointer
 func convTstring(val string) unsafe.Pointer
 func convTslice(val []uint8) unsafe.Pointer
 
-// Type to empty-interface conversion.
-func convT2E(typ *byte, elem *any) (ret any)
-func convT2Enoptr(typ *byte, elem *any) (ret any)
-
-// Type to non-empty-interface conversion.
-func convT2I(tab *byte, elem *any) (ret any)
-func convT2Inoptr(tab *byte, elem *any) (ret any)
-
 // interface type assertions x.(T)
 func assertE2I(inter *byte, typ *byte) *byte
 func assertE2I2(inter *byte, eface any) (ret any)