From: Cherry Zhang <cherryyz@google.com>
Date: Thu, 8 Apr 2021 18:41:44 +0000 (-0400)
Subject: cmd/compile: don't use fast32/64 map functions for aggregates
X-Git-Tag: go1.17beta1~764
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=6c98ecda100c2e3f8325d0b958f53aeaeb92c101;p=gostls13.git

cmd/compile: don't use fast32/64 map functions for aggregates

Under register ABI, aggregates like [2]uint32 is passed
differently than a uint64. For now, don't use the fast version
of the map functions for non-trivial aggregates.

GOEXPERIMENT=regabi,regabiargs can now pass make.bash, modulo
staleness checks.

TODO: maybe find some way to use the fast functions. Maybe
unsafe-cast to uint32/64 then call the map function. But need to
make the type checker happy.

Change-Id: If42717280dde12636fb970798cf1ca8fb29a3d06
Reviewed-on: https://go-review.googlesource.com/c/go/+/308650
Trust: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: David Chase <drchase@google.com>
---

diff --git a/src/cmd/compile/internal/walk/walk.go b/src/cmd/compile/internal/walk/walk.go
index d889786c72..1f0b777263 100644
--- a/src/cmd/compile/internal/walk/walk.go
+++ b/src/cmd/compile/internal/walk/walk.go
@@ -14,6 +14,7 @@ import (
 	"cmd/compile/internal/ssagen"
 	"cmd/compile/internal/typecheck"
 	"cmd/compile/internal/types"
+	"cmd/internal/objabi"
 	"cmd/internal/src"
 )
 
@@ -203,6 +204,13 @@ func mapfast(t *types.Type) int {
 	}
 	switch reflectdata.AlgType(t.Key()) {
 	case types.AMEM32:
+		if objabi.Experiment.RegabiArgs && t.Key().NumComponents(types.CountBlankFields) != 1 {
+			// If key has multiple components, under register ABI it will
+			// be passed differently than uint32.
+			// TODO: maybe unsafe-case to uint32. But needs to make the type
+			// checker happy.
+			return mapslow
+		}
 		if !t.Key().HasPointers() {
 			return mapfast32
 		}
@@ -211,6 +219,10 @@ func mapfast(t *types.Type) int {
 		}
 		base.Fatalf("small pointer %v", t.Key())
 	case types.AMEM64:
+		if objabi.Experiment.RegabiArgs && t.Key().NumComponents(types.CountBlankFields) != 1 {
+			// See above.
+			return mapslow
+		}
 		if !t.Key().HasPointers() {
 			return mapfast64
 		}