Author: bdragon
Date: Tue Sep 8 01:27:03 2020
New Revision: 365441
URL: https://svnweb.freebsd.org/changeset/base/365441
Log:
[PowerPC] Work around -O miscompile on powerpc 32 bit.
Work around llvm 11 miscompile in 32 bit powerpc that appears to cause ifuncs
to branch to the wrong address by forcing -O2. This worked in previous
versions because -O was mapped to -O2 previously (but is now -O1.)
While here, remove the old temporary workaround from r224882 that does the
opposite thing for powerpc non-DEBUG kernels, bringing it in line with other
platforms that compile at -O2.
This fixes kernel boot on powerpc and powerpcspe after the llvm11 transition.
Sponsored by: Tag1 Consulting, Inc.
Modified:
head/sys/conf/kern.pre.mk
Modified: head/sys/conf/kern.pre.mk
==============================================================================
--- head/sys/conf/kern.pre.mk Tue Sep 8 00:48:18 2020 (r365440)
+++ head/sys/conf/kern.pre.mk Tue Sep 8 01:27:03 2020 (r365441)
@@ -51,14 +51,15 @@ OBJCOPY?= objcopy
SIZE?= size
.if defined(DEBUG)
+.if ${MACHINE_ARCH} == "powerpc" || ${MACHINE_ARCH} == "powerpcspe"
+# Work around clang 11 miscompile on 32 bit powerpc.
+_MINUS_O= -O2
+.else
_MINUS_O= -O
+.endif
CTFFLAGS+= -g
.else
-.if ${MACHINE_CPUARCH} == "powerpc"
-_MINUS_O= -O # gcc miscompiles some code at -O2
-.else
_MINUS_O= -O2
-.endif
.endif
.if ${MACHINE_CPUARCH} == "amd64"
.if ${COMPILER_TYPE} == "clang"
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