all: explode GOEXPERIMENT=regabi into 5 sub-experiments

This separates GOEXPERIMENT=regabi into five sub-experiments:
regabiwrappers, regabig, regabireflect, regabidefer, and regabiargs.
Setting GOEXPERIMENT=regabi now implies the working subset of these
(currently, regabiwrappers, regabig, and regabireflect).

This simplifies testing, helps derisk the register ABI project,
and will also help with performance comparisons.

This replaces the -abiwrap flag to the compiler and linker with
the regabiwrappers experiment.

As part of this, regabiargs now enables registers for all calls
in the compiler. Previously, this was statically disabled in
regabiEnabledForAllCompilation, but now that we can control it
independently, this isn't necessary.

For #40724.

Change-Id: I5171e60cda6789031f2ef034cc2e7c5d62459122
Reviewed-on: https://go-review.googlesource.com/c/go/+/302070
Trust: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: David Chase <drchase@google.com>

1 files changed, 24 insertions, 6 deletions

diff --git a/src/cmd/asm/internal/lex/input.go b/src/cmd/asm/internal/lex/input.go
index 1d4d4be7bd..d3ad328954 100644
--- a/src/cmd/asm/internal/lex/input.go
+++ b/src/cmd/asm/internal/lex/input.go
@@ -46,12 +46,30 @@ func NewInput(name string) *Input {
 func predefine(defines flags.MultiFlag) map[string]*Macro {
 	macros := make(map[string]*Macro)
 
-	if *flags.CompilingRuntime && objabi.Regabi_enabled != 0 {
-		const name = "GOEXPERIMENT_REGABI"
-		macros[name] = &Macro{
-			name:   name,
-			args:   nil,
-			tokens: Tokenize("1"),
+	// Set macros for various GOEXPERIMENTs so we can easily
+	// switch runtime assembly code based on them.
+	if *flags.CompilingRuntime {
+		set := func(name string) {
+			macros[name] = &Macro{
+				name:   name,
+				args:   nil,
+				tokens: Tokenize("1"),
+			}
+		}
+		if objabi.Experiment.RegabiWrappers {
+			set("GOEXPERIMENT_REGABI_WRAPPERS")
+		}
+		if objabi.Experiment.RegabiG {
+			set("GOEXPERIMENT_REGABI_G")
+		}
+		if objabi.Experiment.RegabiReflect {
+			set("GOEXPERIMENT_REGABI_REFLECT")
+		}
+		if objabi.Experiment.RegabiDefer {
+			set("GOEXPERIMENT_REGABI_DEFER")
+		}
+		if objabi.Experiment.RegabiArgs {
+			set("GOEXPERIMENT_REGABI_ARGS")
 		}
 	}