From 4a7c4c76e06b6f2e5a8eef4dc7eb0d93d2754755 Mon Sep 17 00:00:00 2001
From: Roland McGrath <mcgrathr@google.com>
Date: Mon, 13 May 2019 21:01:33 +0000
Subject: [PATCH] [libc] Make sure libc doesn't link against libc++
Bug: ZX-4099 #done
Change-Id: I23e6d4b163ddc8616a22decc2029424888305cdf
---
zircon/system/ulib/c/BUILD.gn | 3 +++
zircon/third_party/lib/cortex-strings/README.fuchsia | 1 +
.../third_party/lib/cortex-strings/src/aarch64/memmove.S | 9 ++++++++-
3 files changed, 12 insertions(+), 1 deletion(-)
diff --git a/zircon/system/ulib/c/BUILD.gn b/zircon/system/ulib/c/BUILD.gn
index 4b50f98be28..252447012c1 100644
--- a/zircon/system/ulib/c/BUILD.gn
+++ b/zircon/system/ulib/c/BUILD.gn
@@ -25,6 +25,9 @@ library("c") {
# Suppress the ${toolchain.implicit_deps} that points back to here.
no_implicit_deps = true
+ # Don't link against the shared libc++.
+ configs += [ "$zx/public/gn/config:static-libc++" ]
+
# TODO(BLD-353): temporary kludges; see //zircon/public/sysroot
metadata = {
legacy_sysroot = [
diff --git a/zircon/third_party/lib/cortex-strings/README.fuchsia b/zircon/third_party/lib/cortex-strings/README.fuchsia
index 9934c6eba1e..2b9a99f3987 100644
--- a/zircon/third_party/lib/cortex-strings/README.fuchsia
+++ b/zircon/third_party/lib/cortex-strings/README.fuchsia
@@ -13,3 +13,4 @@ Modifications:
- The no-neon directory is taken from an earlier revision of the same repo:
bc654e7a594385071b42db3c9c94bd0fd5fe0da5
It contains only a subset of src/aarch64 from that revision.
+- Added ".Lmemcpy" branch veneer to src/aarch64/memmove.S
diff --git a/zircon/third_party/lib/cortex-strings/src/aarch64/memmove.S b/zircon/third_party/lib/cortex-strings/src/aarch64/memmove.S
index c9fe6c1f571..9a3fc8e08b5 100644
--- a/zircon/third_party/lib/cortex-strings/src/aarch64/memmove.S
+++ b/zircon/third_party/lib/cortex-strings/src/aarch64/memmove.S
@@ -93,7 +93,11 @@ def_fn memmove, 6
sub tmp1, dstin, src
cmp count, 96
ccmp tmp1, count, 2, hi
- b.hs memcpy
+ // The linker doesn't generate a veneer for a conditional branch
+ // whose target is too far away, so we need to use our own "veneer".
+ // Unfortunately that introduces the extra jump even when the
+ // distance would allow removing it, because only the linker knows.
+ b.hs .Lmemcpy
cbz tmp1, 3f
add dstend, dstin, count
@@ -147,4 +151,7 @@ def_fn memmove, 6
stp C_l, C_h, [dstin]
3: ret
+.Lmemcpy:
+ b memcpy
+
.size memmove, . - memmove
--
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