From fac6dee9eb58b2b558fec2aea749460ca623f6d6 Mon Sep 17 00:00:00 2001
From: Eric van Gyzen <vangyzen@FreeBSD.org>
Date: Tue, 12 May 2020 15:22:40 +0000
Subject: [PATCH] Remove tests for obsolete compilers in the build system

Assume gcc is at least 6.4, the oldest xtoolchain in the ports tree.
Assume clang is at least 6, which was in 11.2-RELEASE.  Drop conditions
for older compilers.

Reviewed by:	imp (earlier version), emaste, jhb
MFC after:	2 weeks
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D24802
---
 lib/libclang_rt/Makefile.inc  |  2 +-
 lib/libthr/Makefile           |  3 --
 lib/msun/Makefile             |  4 +--
 libexec/rtld-elf/Makefile     |  4 ---
 libexec/tftpd/tests/Makefile  |  3 --
 share/mk/bsd.compiler.mk      | 14 ++-------
 share/mk/bsd.sys.mk           | 56 +++++++++--------------------------
 stand/arm/uboot/Makefile      |  2 +-
 stand/defs.mk                 |  4 ---
 stand/efi/Makefile            |  6 ----
 stand/efi/boot1/Makefile      |  4 ---
 stand/efi/loader/Makefile     |  4 ---
 stand/i386/boot2/Makefile     |  3 --
 stand/i386/isoboot/Makefile   |  3 --
 stand/libsa/Makefile          |  4 ---
 sys/conf/Makefile.arm         |  4 ---
 sys/conf/Makefile.powerpc     |  2 +-
 sys/conf/kern.mk              | 36 +++++-----------------
 sys/conf/kern.post.mk         |  3 --
 sys/conf/kern.pre.mk          |  4 ---
 sys/conf/kmod.mk              | 11 -------
 sys/modules/Makefile          |  2 --
 usr.sbin/acpi/acpidb/Makefile |  2 +-
 usr.sbin/trpt/Makefile        |  6 ----
 usr.sbin/zic/zic/Makefile     |  2 +-
 25 files changed, 32 insertions(+), 156 deletions(-)

diff --git a/lib/libclang_rt/Makefile.inc b/lib/libclang_rt/Makefile.inc
index 80820469301..8d829c9210a 100644
--- a/lib/libclang_rt/Makefile.inc
+++ b/lib/libclang_rt/Makefile.inc
@@ -32,7 +32,7 @@ CFLAGS+=	${PICFLAG}
 CFLAGS+=	-fno-builtin
 CFLAGS+=	-fno-exceptions
 CXXFLAGS+=	-fno-rtti
-.if ${COMPILER_TYPE} == clang && ${COMPILER_VERSION} >= 30700
+.if ${COMPILER_TYPE} == clang
 CFLAGS+=	-fno-sanitize=safe-stack
 .endif
 CFLAGS+=	-fno-stack-protector
diff --git a/lib/libthr/Makefile b/lib/libthr/Makefile
index 5f3d52661c9..c77b6b565a8 100644
--- a/lib/libthr/Makefile
+++ b/lib/libthr/Makefile
@@ -29,10 +29,7 @@ CFLAGS+=-Winline
 
 CFLAGS.thr_stack.c+=	-Wno-cast-align
 CFLAGS.rtld_malloc.c+=	-Wno-cast-align
-.include <bsd.compiler.mk>
-.if !(${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} < 40300)
 CFLAGS.thr_symbols.c+=	-Wno-missing-variable-declarations
-.endif
 
 .ifndef NO_THREAD_UNWIND_STACK
 CFLAGS+=-fexceptions
diff --git a/lib/msun/Makefile b/lib/msun/Makefile
index 6c9af4c018c..4491bc216a4 100644
--- a/lib/msun/Makefile
+++ b/lib/msun/Makefile
@@ -108,13 +108,13 @@ COMMON_SRCS+=	catrigl.c \
 	s_nextafterl.c s_nexttoward.c s_remquol.c s_rintl.c s_roundl.c \
 	s_scalbnl.c s_sinl.c s_sincosl.c \
 	s_tanhl.c s_tanl.c s_truncl.c w_cabsl.c
-# Work around this warning from gcc 6:
+# Work around this warning from gcc:
 #     lib/msun/ld80/e_powl.c:275:1: error: floating constant exceeds range of
 #     'long double' [-Werror=overflow]
 #     if( y >= LDBL_MAX )
 # See also: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=130067
 .include <bsd.compiler.mk>
-.if ${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} >= 60000
+.if ${COMPILER_TYPE} == "gcc"
 CFLAGS.e_powl.c+= -Wno-error=overflow
 .endif
 .endif
diff --git a/libexec/rtld-elf/Makefile b/libexec/rtld-elf/Makefile
index b83c8357284..23a0f99af2c 100644
--- a/libexec/rtld-elf/Makefile
+++ b/libexec/rtld-elf/Makefile
@@ -90,8 +90,4 @@ ${PROG_FULL}:	${VERSION_MAP}
 # GCC warns about redeclarations even though they have __exported
 # and are therefore not identical to the ones from the system headers.
 CFLAGS+=	-Wno-redundant-decls
-.if ${COMPILER_VERSION} < 40300
-# Silence -Wshadow false positives in ancient GCC
-CFLAGS+=	-Wno-shadow
-.endif
 .endif
diff --git a/libexec/tftpd/tests/Makefile b/libexec/tftpd/tests/Makefile
index 9aa420cec1a..390921e31de 100644
--- a/libexec/tftpd/tests/Makefile
+++ b/libexec/tftpd/tests/Makefile
@@ -2,11 +2,8 @@
 
 .include <bsd.own.mk>
 
-# Skip on GCC 4.2, because it lacks __COUNTER__
-.if ${COMPILER_TYPE} != "gcc" || ${COMPILER_VERSION} >= 40300
 ATF_TESTS_C=	functional
 TEST_METADATA.functional+=	timeout=15
-.endif
 
 LIBADD=	util
 WARNS?=	6
diff --git a/share/mk/bsd.compiler.mk b/share/mk/bsd.compiler.mk
index 2902e8b01f2..ffea2c9e125 100644
--- a/share/mk/bsd.compiler.mk
+++ b/share/mk/bsd.compiler.mk
@@ -205,20 +205,12 @@ ${X_}COMPILER_FREEBSD_VERSION=	unknown
 ${X_}COMPILER_RESOURCE_DIR!=	${${cc}:N${CCACHE_BIN}} -print-resource-dir 2>/dev/null || echo unknown
 .endif
 
-${X_}COMPILER_FEATURES=
-.if (${${X_}COMPILER_TYPE} == "clang" && ${${X_}COMPILER_VERSION} >= 30300) || \
-	(${${X_}COMPILER_TYPE} == "gcc" && ${${X_}COMPILER_VERSION} >= 40800)
-${X_}COMPILER_FEATURES+=	c++11
-.endif
-.if (${${X_}COMPILER_TYPE} == "clang" && ${${X_}COMPILER_VERSION} >= 30400) || \
-	(${${X_}COMPILER_TYPE} == "gcc" && ${${X_}COMPILER_VERSION} >= 50000)
-${X_}COMPILER_FEATURES+=	c++14
-.endif
-.if (${${X_}COMPILER_TYPE} == "clang" && ${${X_}COMPILER_VERSION} >= 50000) || \
+${X_}COMPILER_FEATURES=		c++11 c++14
+.if ${${X_}COMPILER_TYPE} == "clang" || \
 	(${${X_}COMPILER_TYPE} == "gcc" && ${${X_}COMPILER_VERSION} >= 70000)
 ${X_}COMPILER_FEATURES+=	c++17
 .endif
-.if ${${X_}COMPILER_TYPE} == "clang" && ${${X_}COMPILER_VERSION} >= 60000
+.if ${${X_}COMPILER_TYPE} == "clang"
 ${X_}COMPILER_FEATURES+=	retpoline
 .endif
 
diff --git a/share/mk/bsd.sys.mk b/share/mk/bsd.sys.mk
index b003bb68a2c..d2c73d95b2a 100644
--- a/share/mk/bsd.sys.mk
+++ b/share/mk/bsd.sys.mk
@@ -6,8 +6,7 @@
 # Enable various levels of compiler warning checks.  These may be
 # overridden (e.g. if using a non-gcc compiler) by defining MK_WARNS=no.
 
-# for 4.2.1 GCC:   http://gcc.gnu.org/onlinedocs/gcc-4.2.1/gcc/Warning-Options.html
-# for current GCC: https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
+# for GCC:   https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
 # for clang: https://clang.llvm.org/docs/DiagnosticsReference.html
 
 .include <bsd.compiler.mk>
@@ -29,15 +28,6 @@ CFLAGS+=	-std=${CSTD}
 CXXFLAGS+=	-std=${CXXSTD}
 .endif
 
-#
-# Turn off -Werror for gcc 4.2.1. The compiler is on the glide path out of the
-# system, and any warnings specific to it are no longer relevant as there are
-# too many false positives.
-#
-.if ${COMPILER_VERSION} <  50000
-NO_WERROR.gcc=	yes
-.endif
-
 # -pedantic is problematic because it also imposes namespace restrictions
 #CFLAGS+=	-pedantic
 .if defined(WARNS)
@@ -81,19 +71,13 @@ CWARNFLAGS+=	-Wno-pointer-sign
 # is set to low values, these have to be disabled explicitly.
 .if ${WARNS} <= 6
 CWARNFLAGS.clang+=	-Wno-empty-body -Wno-string-plus-int
-.if ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 30400
 CWARNFLAGS.clang+=	-Wno-unused-const-variable
-.endif
 .endif # WARNS <= 6
 .if ${WARNS} <= 3
 CWARNFLAGS.clang+=	-Wno-tautological-compare -Wno-unused-value\
 		-Wno-parentheses-equality -Wno-unused-function -Wno-enum-conversion
-.if ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 30600
 CWARNFLAGS.clang+=	-Wno-unused-local-typedef
-.endif
-.if ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 40000
 CWARNFLAGS.clang+=	-Wno-address-of-packed-member
-.endif
 .if ${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} >= 90100
 CWARNFLAGS.gcc+=	-Wno-address-of-packed-member
 .endif
@@ -113,7 +97,7 @@ CWARNFLAGS.clang+=	-Wno-array-bounds
 .endif # NO_WARRAY_BOUNDS
 .if defined(NO_WMISLEADING_INDENTATION) && \
     ((${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 100000) || \
-     (${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} >= 60100))
+      ${COMPILER_TYPE} == "gcc")
 CWARNFLAGS+=		-Wno-misleading-indentation
 .endif # NO_WMISLEADING_INDENTATION
 .endif # WARNS
@@ -137,8 +121,10 @@ CWARNFLAGS+=	-Werror
 CWARNFLAGS+=	-Wno-format
 .endif # NO_WFORMAT || NO_WFORMAT.${COMPILER_TYPE}
 
-# GCC 5.2.0
-.if ${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} >= 50200
+# GCC
+# We should clean up warnings produced with these flags.
+# They were originally added as a quick hack to enable gcc5/6.
+.if ${COMPILER_TYPE} == "gcc"
 CWARNFLAGS+=	-Wno-error=address			\
 		-Wno-error=array-bounds			\
 		-Wno-error=attributes			\
@@ -150,23 +136,18 @@ CWARNFLAGS+=	-Wno-error=address			\
 		-Wno-error=extra			\
 		-Wno-error=inline			\
 		-Wno-error=logical-not-parentheses	\
+		-Wno-error=nonnull-compare		\
+		-Wno-error=shift-negative-value		\
 		-Wno-error=strict-aliasing		\
+		-Wno-error=tautological-compare		\
 		-Wno-error=uninitialized		\
 		-Wno-error=unused-but-set-variable	\
+		-Wno-error=unused-const-variable	\
 		-Wno-error=unused-function		\
 		-Wno-error=unused-value
-.endif
-
-# GCC 6.1.0
-.if ${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} >= 60100
-CWARNFLAGS+=	-Wno-error=nonnull-compare		\
-		-Wno-error=shift-negative-value		\
-		-Wno-error=tautological-compare		\
-		-Wno-error=unused-const-variable
-.endif
 
 # GCC 7.1.0
-.if ${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} >= 70100
+.if ${COMPILER_VERSION} >= 70100
 CWARNFLAGS+=	-Wno-error=bool-operation		\
 		-Wno-error=deprecated			\
 		-Wno-error=expansion-to-defined		\
@@ -182,7 +163,7 @@ CWARNFLAGS+=	-Wno-error=bool-operation		\
 .endif
 
 # GCC 8.1.0
-.if ${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} >= 80100
+.if ${COMPILER_VERSION} >= 80100
 CWARNFLAGS+=	-Wno-error=aggressive-loop-optimizations	\
 		-Wno-error=cast-function-type			\
 		-Wno-error=catch-value				\
@@ -191,9 +172,10 @@ CWARNFLAGS+=	-Wno-error=aggressive-loop-optimizations	\
 		-Wno-error=sizeof-pointer-memaccess		\
 		-Wno-error=stringop-truncation
 .endif
+.endif	# gcc
 
 # How to handle FreeBSD custom printf format specifiers.
-.if ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 30600
+.if ${COMPILER_TYPE} == "clang"
 FORMAT_EXTENSIONS=	-D__printf__=__freebsd_kprintf__
 .else
 FORMAT_EXTENSIONS=	-fformat-extensions
@@ -223,11 +205,7 @@ CFLAGS+=-nobuiltininc -idirafter ${COMPILER_RESOURCE_DIR}/include
 
 CLANG_OPT_SMALL= -mstack-alignment=8 -mllvm -inline-threshold=3\
 		 -mllvm -simplifycfg-dup-ret
-.if ${COMPILER_VERSION} >= 30500 && ${COMPILER_VERSION} < 30700
-CLANG_OPT_SMALL+= -mllvm -enable-gvn=false
-.else
 CLANG_OPT_SMALL+= -mllvm -enable-load-pre=false
-.endif
 CFLAGS.clang+=	 -Qunused-arguments
 # The libc++ headers use c++11 extensions.  These are normally silenced because
 # they are treated as system headers, but we explicitly disable that warning
@@ -238,14 +216,8 @@ CXXFLAGS.clang+=	 -Wno-c++11-extensions
 
 .if ${MK_SSP} != "no" && \
     ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
-.if (${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 30500) || \
-    (${COMPILER_TYPE} == "gcc" && \
-     (${COMPILER_VERSION} == 40201 || ${COMPILER_VERSION} >= 40900))
 # Don't use -Wstack-protector as it breaks world with -Werror.
 SSP_CFLAGS?=	-fstack-protector-strong
-.else
-SSP_CFLAGS?=	-fstack-protector
-.endif
 CFLAGS+=	${SSP_CFLAGS}
 .endif # SSP && !ARM && !MIPS
 
diff --git a/stand/arm/uboot/Makefile b/stand/arm/uboot/Makefile
index 0c906c99ee6..f99282aa6e5 100644
--- a/stand/arm/uboot/Makefile
+++ b/stand/arm/uboot/Makefile
@@ -24,7 +24,7 @@ UBLDR_LOADADDR?=	0x1000000
 # Architecture-specific loader code
 SRCS=		start.S conf.c self_reloc.c vers.c
 
-.if ${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} > 40201
+.if ${COMPILER_TYPE} == "gcc"
 CWARNFLAGS.self_reloc.c+=	-Wno-error=maybe-uninitialized
 .endif
 
diff --git a/stand/defs.mk b/stand/defs.mk
index 89ccf2f4bdb..776da61e66c 100644
--- a/stand/defs.mk
+++ b/stand/defs.mk
@@ -143,11 +143,7 @@ CFLAGS+=	-fPIC -mno-red-zone
 # Do not generate movt/movw, because the relocation fixup for them does not
 # translate to the -Bsymbolic -pie format required by self_reloc() in loader(8).
 # Also, the fpu is not available in a standalone environment.
-.if ${COMPILER_VERSION} < 30800
-CFLAGS.clang+=	-mllvm -arm-use-movt=0
-.else
 CFLAGS.clang+=	-mno-movt
-.endif
 CFLAGS.clang+=  -mfpu=none
 CFLAGS+=	-fPIC
 .endif
diff --git a/stand/efi/Makefile b/stand/efi/Makefile
index 2e0daba6dab..f6cbede52bd 100644
--- a/stand/efi/Makefile
+++ b/stand/efi/Makefile
@@ -4,16 +4,10 @@ NO_OBJ=t
 
 .include <bsd.init.mk>
 
-# In-tree GCC does not support __attribute__((ms_abi)), but gcc newer
-# than 4.5 supports it.
-.if ${COMPILER_TYPE} != "gcc" || ${COMPILER_VERSION} >= 40500
-
 SUBDIR.${MK_FDT}+=	fdt
 SUBDIR.yes+=	libefi boot1 gptboot
 SUBDIR.${MK_FORTH}+= loader_4th
 SUBDIR.${MK_LOADER_LUA}+= loader_lua
 SUBDIR.yes+=	loader_simp
 
-.endif # ${COMPILER_TYPE} != "gcc" || ${COMPILER_VERSION} >= 40500
-
 .include <bsd.subdir.mk>
diff --git a/stand/efi/boot1/Makefile b/stand/efi/boot1/Makefile
index 56a3eb02899..b8644ace4d4 100644
--- a/stand/efi/boot1/Makefile
+++ b/stand/efi/boot1/Makefile
@@ -42,10 +42,6 @@ CFLAGS.zfs_module.c+=	-I${SYSDIR}/cddl/contrib/opensolaris/common/lz4
 CFLAGS+=	-DEFI_ZFS_BOOT
 .endif
 
-.if ${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} > 40201
-CWARNFLAGS.self_reloc.c+=	-Wno-error=maybe-uninitialized
-.endif
-
 CFLAGS+=	-I${EFIINC}
 CFLAGS+=	-I${EFIINCMD}
 CFLAGS+=	-I${SYSDIR}/contrib/dev/acpica/include
diff --git a/stand/efi/loader/Makefile b/stand/efi/loader/Makefile
index 6ee613e7bfe..73b1975ad3e 100644
--- a/stand/efi/loader/Makefile
+++ b/stand/efi/loader/Makefile
@@ -31,10 +31,6 @@ CFLAGS+=	-DEFI_ZFS_BOOT
 HAVE_ZFS=	yes
 .endif
 
-.if ${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} > 40201
-CWARNFLAGS.self_reloc.c+=	-Wno-error=maybe-uninitialized
-.endif
-
 # We implement a slightly non-standard %S in that it always takes a
 # CHAR16 that's common in UEFI-land instead of a wchar_t. This only
 # seems to matter on arm64 where wchar_t defaults to an int instead
diff --git a/stand/i386/boot2/Makefile b/stand/i386/boot2/Makefile
index 9bb31275b9c..8758261ad45 100644
--- a/stand/i386/boot2/Makefile
+++ b/stand/i386/boot2/Makefile
@@ -37,9 +37,6 @@ CFLAGS+=-fomit-frame-pointer \
 CFLAGS.gcc+=	-Os \
 		-fno-asynchronous-unwind-tables \
 		--param max-inline-insns-single=100
-.if ${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} <= 40201
-CFLAGS.gcc+=   -mno-align-long-strings
-.endif
 
 CFLAGS.clang+=	-Oz ${CLANG_OPT_SMALL}
 
diff --git a/stand/i386/isoboot/Makefile b/stand/i386/isoboot/Makefile
index 9fcd1f35723..67936e16176 100644
--- a/stand/i386/isoboot/Makefile
+++ b/stand/i386/isoboot/Makefile
@@ -32,9 +32,6 @@ CFLAGS+=-DBOOTPROG=\"isoboot\" \
 	-Winline -Wno-pointer-sign
 
 CFLAGS.gcc+=	--param max-inline-insns-single=100
-.if ${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} <= 40201
-CFLAGS.gcc+=	-Wno-uninitialized
-.endif
 CFLAGS.clang+=  -Oz ${CLANG_OPT_SMALL}
 
 LD_FLAGS+=${LD_FLAGS_BIN}
diff --git a/stand/libsa/Makefile b/stand/libsa/Makefile
index b9b70b93e03..d016a07ff0e 100644
--- a/stand/libsa/Makefile
+++ b/stand/libsa/Makefile
@@ -46,11 +46,7 @@ SRCS+=	subr_boot.c
 # Do not generate movt/movw, because the relocation fixup for them does not
 # translate to the -Bsymbolic -pie format required by self_reloc() in loader(8).
 # Also, the fpu is not available in a standalone environment.
-.if ${COMPILER_VERSION} < 30800
-CFLAGS.clang+=	-mllvm -arm-use-movt=0
-.else
 CFLAGS.clang+=	-mno-movt
-.endif
 CFLAGS.clang+=	-mfpu=none
 
 .PATH: ${SRCTOP}/contrib/llvm-project/compiler-rt/lib/builtins/arm/
diff --git a/sys/conf/Makefile.arm b/sys/conf/Makefile.arm
index 23108641ba0..1d0ab347827 100644
--- a/sys/conf/Makefile.arm
+++ b/sys/conf/Makefile.arm
@@ -44,10 +44,6 @@ CFLAGS.clang += -mfpu=none
 
 .if !empty(DDB_ENABLED)
 CFLAGS += -funwind-tables
-.if ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} < 30500
-# clang < 3.5.0 requires us to tell it to emit assembly with unwind information
-CFLAGS += -mllvm -arm-enable-ehabi
-.endif
 .endif
 
 # "makeoptions KERNVIRTADDR=" is now optional, supply the default value.
diff --git a/sys/conf/Makefile.powerpc b/sys/conf/Makefile.powerpc
index f8b5bd6b054..a933c6b4209 100644
--- a/sys/conf/Makefile.powerpc
+++ b/sys/conf/Makefile.powerpc
@@ -51,7 +51,7 @@ DPAAWARNFLAGS += \
         -Wno-error=incompatible-pointer-types-discards-qualifiers \
         -Wno-error=non-literal-null-conversion \
         -Wno-error=enum-conversion
-.elif "${COMPILER_TYPE}" == "gcc" && ${COMPILER_VERSION} >= 50200
+.elif "${COMPILER_TYPE}" == "gcc"
 DPAAWARNFLAGS += \
 	-Wno-error=redundant-decls \
 	-Wno-error=int-in-bool-context
diff --git a/sys/conf/kern.mk b/sys/conf/kern.mk
index 23c98de879b..71abc84247e 100644
--- a/sys/conf/kern.mk
+++ b/sys/conf/kern.mk
@@ -31,19 +31,14 @@ NO_WTAUTOLOGICAL_POINTER_COMPARE= -Wno-tautological-pointer-compare
 CWARNEXTRA?=	-Wno-error-tautological-compare -Wno-error-empty-body \
 		-Wno-error-parentheses-equality -Wno-error-unused-function \
 		-Wno-error-pointer-sign
-.if ${COMPILER_VERSION} >= 30700
 CWARNEXTRA+=	-Wno-error-shift-negative-value
-.endif
-.if ${COMPILER_VERSION} >= 40000
 CWARNEXTRA+=	-Wno-address-of-packed-member
-.endif
 .if ${COMPILER_VERSION} >= 100000
 NO_WMISLEADING_INDENTATION=	-Wno-misleading-indentation
 .endif
-.endif
+.endif	# clang
 
 .if ${COMPILER_TYPE} == "gcc"
-.if ${COMPILER_VERSION} >= 40800
 # Catch-all for all the things that are in our tree, but for which we're
 # not yet ready for this compiler.
 NO_WUNUSED_BUT_SET_VARIABLE = -Wno-unused-but-set-variable
@@ -55,15 +50,13 @@ CWARNEXTRA?=	-Wno-error=address				\
 		-Wno-error=enum-compare				\
 		-Wno-error=inline				\
 		-Wno-error=maybe-uninitialized			\
+		-Wno-error=misleading-indentation		\
+		-Wno-error=nonnull-compare			\
 		-Wno-error=overflow				\
 		-Wno-error=sequence-point			\
-		-Wno-unused-but-set-variable
-.if ${COMPILER_VERSION} >= 60100
-CWARNEXTRA+=	-Wno-error=misleading-indentation		\
-		-Wno-error=nonnull-compare			\
 		-Wno-error=shift-overflow			\
-		-Wno-error=tautological-compare
-.endif
+		-Wno-error=tautological-compare			\
+		-Wno-unused-but-set-variable
 .if ${COMPILER_VERSION} >= 70100
 CWARNEXTRA+=	-Wno-error=stringop-overflow
 .endif
@@ -76,15 +69,7 @@ CWARNEXTRA+=	-Wno-error=packed-not-aligned
 .if ${COMPILER_VERSION} >= 90100
 CWARNEXTRA+=	-Wno-address-of-packed-member
 .endif
-.else
-# For gcc 4.2, eliminate the too-often-wrong warnings about uninitialized vars.
-CWARNEXTRA?=	-Wno-uninitialized
-# GCC 4.2 doesn't have -Wno-error=cast-qual, so just disable the warning for
-# the few files that are already known to generate cast-qual warnings.
-NO_WCAST_QUAL= -Wno-cast-qual
-NO_WNONNULL=	-Wno-nonnull
-.endif
-.endif
+.endif	# gcc
 
 # This warning is utter nonsense
 CWARNFLAGS+=	-Wno-format-zero-length
@@ -93,7 +78,7 @@ CWARNFLAGS+=	-Wno-format-zero-length
 # to be disabled.  WARNING: format checking is disabled in this case.
 .if ${MK_FORMAT_EXTENSIONS} == "no"
 FORMAT_EXTENSIONS=	-Wno-format
-.elif ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 30600
+.elif ${COMPILER_TYPE} == "clang"
 FORMAT_EXTENSIONS=	-D__printf__=__freebsd_kprintf__
 .else
 FORMAT_EXTENSIONS=	-fformat-extensions
@@ -201,12 +186,7 @@ CFLAGS.gcc+=	-mno-spe
 # DDB happy. ELFv2, if available, has some other efficiency benefits.
 #
 .if ${MACHINE_ARCH} == "powerpc64"
-.if ${COMPILER_VERSION} >= 40900
-CFLAGS.gcc+=	-mabi=elfv2
-.else
-CFLAGS.gcc+=	-mcall-aixdesc
-.endif
-CFLAGS.clang+=	-mabi=elfv2
+CFLAGS+=	-mabi=elfv2
 .endif
 
 #
diff --git a/sys/conf/kern.post.mk b/sys/conf/kern.post.mk
index 529a02ac679..883c8d8b52f 100644
--- a/sys/conf/kern.post.mk
+++ b/sys/conf/kern.post.mk
@@ -345,10 +345,7 @@ ${__obj}: ${OBJS_DEPEND_GUESS.${__obj}}
 
 .depend: .PRECIOUS ${SRCS}
 
-.if ${COMPILER_TYPE} == "clang" || \
-    (${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} >= 60000)
 _MAP_DEBUG_PREFIX= yes
-.endif
 
 _ILINKS= machine
 .if ${MACHINE} != ${MACHINE_CPUARCH} && ${MACHINE} != "arm64"
diff --git a/sys/conf/kern.pre.mk b/sys/conf/kern.pre.mk
index b1b01e3a2eb..2436269c893 100644
--- a/sys/conf/kern.pre.mk
+++ b/sys/conf/kern.pre.mk
@@ -93,11 +93,7 @@ CFLAGS.gcc+= -fms-extensions
 .if defined(CFLAGS_ARCH_PARAMS)
 CFLAGS.gcc+=${CFLAGS_ARCH_PARAMS}
 .endif
-.if ${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} < 50000
-WERROR?=	-Wno-error
-.else
 WERROR?=	-Werror
-.endif
 # The following should be removed no earlier than LLVM11 being imported into the
 # tree, to ensure we don't regress the build.  LLVM11 and GCC10 will switch the
 # default over to -fno-common, making this redundant.
diff --git a/sys/conf/kmod.mk b/sys/conf/kmod.mk
index d1f98ef51cf..f48ee46f956 100644
--- a/sys/conf/kmod.mk
+++ b/sys/conf/kmod.mk
@@ -88,11 +88,7 @@ __KLD_SHARED=no
 .if !empty(CFLAGS:M-O[23s]) && empty(CFLAGS:M-fno-strict-aliasing)
 CFLAGS+=	-fno-strict-aliasing
 .endif
-.if ${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} < 50000
-WERROR?=	-Wno-error
-.else
 WERROR?=	-Werror
-.endif
 
 LINUXKPI_GENSRCS+= \
 	bus_if.h \
@@ -160,11 +156,7 @@ CFLAGS+=	-fPIC
 # Temporary workaround for PR 196407, which contains the fascinating details.
 # Don't allow clang to use fpu instructions or registers in kernel modules.
 .if ${MACHINE_CPUARCH} == arm
-.if ${COMPILER_VERSION} < 30800
-CFLAGS.clang+=	-mllvm -arm-use-movt=0
-.else
 CFLAGS.clang+=	-mno-movt
-.endif
 CFLAGS.clang+=	-mfpu=none
 CFLAGS+=	-funwind-tables
 .endif
@@ -283,10 +275,7 @@ ${FULLPROG}: ${OBJS}
 	${OBJCOPY} --strip-debug ${.TARGET}
 .endif
 
-.if ${COMPILER_TYPE} == "clang" || \
-    (${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} >= 60000)
 _MAP_DEBUG_PREFIX= yes
-.endif
 
 _ILINKS=machine
 .if ${MACHINE_CPUARCH} == "i386" || ${MACHINE_CPUARCH} == "amd64"
diff --git a/sys/modules/Makefile b/sys/modules/Makefile
index b7641713c8e..499a3af7a48 100644
--- a/sys/modules/Makefile
+++ b/sys/modules/Makefile
@@ -620,10 +620,8 @@ _aac=		aac
 _aacraid=	aacraid
 _acpi=		acpi
 .if ${MK_CRYPT} != "no" || defined(ALL_MODULES)
-.if ${COMPILER_TYPE} != "gcc" || ${COMPILER_VERSION} > 40201
 _aesni=		aesni
 .endif
-.endif
 _amd_ecc_inject=amd_ecc_inject
 _amdsbwd=	amdsbwd
 _amdsmn=	amdsmn
diff --git a/usr.sbin/acpi/acpidb/Makefile b/usr.sbin/acpi/acpidb/Makefile
index 566794fa6f4..5a6fceb2a4c 100644
--- a/usr.sbin/acpi/acpidb/Makefile
+++ b/usr.sbin/acpi/acpidb/Makefile
@@ -87,6 +87,6 @@ LIBADD=	pthread
 # integer to pointer, which is a GNU extension.
 #
 # Turn off the warning, because this is in contributed code.
-.if ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 60000
+.if ${COMPILER_TYPE} == "clang"
 CWARNFLAGS+=	-Wno-null-pointer-arithmetic
 .endif
diff --git a/usr.sbin/trpt/Makefile b/usr.sbin/trpt/Makefile
index 4756cb1a0d0..33a3d1f81a7 100644
--- a/usr.sbin/trpt/Makefile
+++ b/usr.sbin/trpt/Makefile
@@ -8,18 +8,12 @@ MAN=	trpt.8
 BINGRP=	kmem
 BINMODE= 2555
 
-.if ${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} < 50000
-WARNS?=	4
-.endif
-
 .if ${MK_INET6_SUPPORT} != "no"
 CFLAGS+= -DINET6
 .endif
 
 .include <bsd.prog.mk>
 
-.if ${COMPILER_TYPE} != "gcc" || ${COMPILER_VERSION} >= 50000
 # Several included system headers tickle this warning in ways that are
 # difficult to work around in this program.
 CFLAGS+= -Wno-missing-variable-declarations
-.endif
diff --git a/usr.sbin/zic/zic/Makefile b/usr.sbin/zic/zic/Makefile
index 36cc79009b4..17ffb33a57e 100644
--- a/usr.sbin/zic/zic/Makefile
+++ b/usr.sbin/zic/zic/Makefile
@@ -15,7 +15,7 @@ CFLAGS+= -I${.CURDIR:H} -I${SRCTOP}/contrib/tzcode/stdtime
 
 WARNS?=	2
 
-.if ${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} >= 50300
+.if ${COMPILER_TYPE} == "gcc"
 CWARNFLAGS+=	-Wno-error=strict-overflow
 .endif