From: Than McIntosh <thanm@golang.org>
Date: Thu, 19 Dec 2024 17:58:40 +0000 (-0500)
Subject: internal/buildcfg: enable DWARF version 5 by default
X-Git-Tag: go1.25rc1~754
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=ca19f987ca74605ef977c7a8619a344504c72272;p=gostls13.git

internal/buildcfg: enable DWARF version 5 by default

This patch enables the DWARF version 5 experiment by default for most
platforms that support DWARF. Note that MacOS is kept at version 4,
due to problems with CGO builds; the "dsymutil" tool from older
versions of Xcode (prior to V16) can't handle DWARF5. Similar we keep
DWARF 4 for GOOS=aix, where XCOFF doesn't appear to support the new
section subtypes in DWARF 5.

Updates #26379.

Change-Id: I5edd600c611f03ce8e11be3ca18c1e6686ac74ef
Reviewed-on: https://go-review.googlesource.com/c/go/+/637895
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>
---

diff --git a/src/internal/buildcfg/exp.go b/src/internal/buildcfg/exp.go
index 9c9ec2c711..2dd6045979 100644
--- a/src/internal/buildcfg/exp.go
+++ b/src/internal/buildcfg/exp.go
@@ -73,6 +73,17 @@ func ParseGOEXPERIMENT(goos, goarch, goexp string) (*ExperimentFlags, error) {
 		haveXchg8 = true
 	}
 
+	// Older versions (anything before V16) of dsymutil don't handle
+	// the .debug_rnglists section in DWARF5. See
+	// https://github.com/golang/go/issues/26379#issuecomment-2677068742
+	// for more context. This disables all DWARF5 on mac, which is not
+	// ideal (would be better to disable just for cases where we know
+	// the build will use external linking). In the GOOS=aix case, the
+	// XCOFF format (as far as can be determined) doesn't seem to
+	// support the necessary section subtypes for DWARF-specific
+	// things like .debug_addr (needed for DWARF 5).
+	dwarf5Supported := (goos != "dwarwin" && goos != "ios" && goos != "aix")
+
 	baseline := goexperiment.Flags{
 		RegabiWrappers:  regabiSupported,
 		RegabiArgs:      regabiSupported,
@@ -80,6 +91,7 @@ func ParseGOEXPERIMENT(goos, goarch, goexp string) (*ExperimentFlags, error) {
 		SwissMap:        true,
 		SpinbitMutex:    haveXchg8,
 		SyncHashTrieMap: true,
+		Dwarf5:          dwarf5Supported,
 	}
 
 	// Start with the statically enabled set of experiments.