On 8 September 2017 at 09:48, Laszlo Ersek <[email protected]> wrote: > On 09/08/17 09:01, Thomas Lamprecht wrote: >> TianoCore BZ#700 [1] >> >> Set the '-Wno-unused-const-variables' in RELEASE builds with the >> GGC49 and GCC5 toolchain. >> >> This fixes the RELEASE build of OVMF with GCC in version 6 or newer. >> GCC 6 added the '-Wunused-const-variable' warning, which gets >> activated by '-Wunused-variable' and has the following behavior: >> "Warn whenever a constant static variable is unused aside from its >> declaration" [2] >> >> Commit 2ad6ba80a1bd58382bde6b994070f7c01d2fb48d introduced a case >> where exactly this happens on a RELEASE build. All uses of the static >> const variable are located in debug code only, which gets thrown out >> by the compiler on RELEASE builds and thus triggers the >> unused-const-variable warning. >> >> There is currently no GCC 6 toolchain target defined and doing so >> would add a lot of boilerplate code. Instead, use the fact that GCC >> ignores unknown '-Wno-*' options: >> >> "[...] if the -Wno- form is used [...] no diagnostic is produced for >> -Wno-unknown-warning unless other diagnostics are being produced" >> >> This behavior is available in GCC 4.9 [3] (and also earlier, for that >> matter), so add the flag to the GCC49 and GCC5 toolchain, even if >> both GCC versions do not supports it. >> GCC49 doesn't enables LTO whereas GCC5 does. As GCC 6.0 through 6.2 >> had bugs relating to LTO there can be desire to use the GCC49 target >> even if compiling with GCC 6, see 432f1d83f77a. >> >> Orient the changes on 20d00edf21d2 which moved the >> '-Wno-unused-but-set-variable' flag to RELEASE builds only, as there >> it ensure that it does not gets raised if the only usage of a >> variable is in (then collapsed) debug code. >> >> [1] https://bugzilla.tianocore.org/show_bug.cgi?id=700 >> [2] >> https://gcc.gnu.org/onlinedocs/gcc-6.4.0/gcc/Warning-Options.html#index-Wunused-const-variable >> [3] https://gcc.gnu.org/onlinedocs/gcc-4.9.0/gcc/Warning-Options.html >> >> Cc: Yonghong Zhu <[email protected]> >> Cc: Liming Gao <[email protected]> >> Cc: Laszlo Ersek <[email protected]> >> Cc: Ard Biesheuvel <[email protected]> >> Contributed-under: TianoCore Contribution Agreement 1.1 >> Signed-off-by: Thomas Lamprecht <[email protected]>
Reviewed-by: Ard Biesheuvel <[email protected]> >> --- >> >> changes v1 -> v2: >> * add the flag also to the GCC49 toolchain to allow using GCC 6 with >> LTO disabled builds, thanks for the hints Laszlo and Liming! >> * adapt commit message slightly, especially to the fact that GCC49 >> gets the flag now too. >> * CC Ard >> >> BaseTools/Conf/tools_def.template | 16 ++++++++-------- >> 1 file changed, 8 insertions(+), 8 deletions(-) >> >> diff --git a/BaseTools/Conf/tools_def.template >> b/BaseTools/Conf/tools_def.template >> index ba1d1a16de..cbb5024c1b 100755 >> --- a/BaseTools/Conf/tools_def.template >> +++ b/BaseTools/Conf/tools_def.template >> @@ -5179,7 +5179,7 @@ RELEASE_GCC48_AARCH64_CC_FLAGS = >> DEF(GCC48_AARCH64_CC_FLAGS) -Wno-unused-but-s >> *_GCC49_IA32_NASM_FLAGS = -f elf32 >> >> DEBUG_GCC49_IA32_CC_FLAGS = DEF(GCC49_IA32_CC_FLAGS) -Os >> -RELEASE_GCC49_IA32_CC_FLAGS = DEF(GCC49_IA32_CC_FLAGS) -Os >> -Wno-unused-but-set-variable >> +RELEASE_GCC49_IA32_CC_FLAGS = DEF(GCC49_IA32_CC_FLAGS) -Os >> -Wno-unused-but-set-variable -Wno-unused-const-variable >> NOOPT_GCC49_IA32_CC_FLAGS = DEF(GCC49_IA32_CC_FLAGS) -O0 >> >> ################## >> @@ -5207,7 +5207,7 @@ RELEASE_GCC49_IA32_CC_FLAGS = >> DEF(GCC49_IA32_CC_FLAGS) -Os -Wno-unused-but >> *_GCC49_X64_NASM_FLAGS = -f elf64 >> >> DEBUG_GCC49_X64_CC_FLAGS = DEF(GCC49_X64_CC_FLAGS) -Os >> -RELEASE_GCC49_X64_CC_FLAGS = DEF(GCC49_X64_CC_FLAGS) -Os >> -Wno-unused-but-set-variable >> +RELEASE_GCC49_X64_CC_FLAGS = DEF(GCC49_X64_CC_FLAGS) -Os >> -Wno-unused-but-set-variable -Wno-unused-const-variable >> NOOPT_GCC49_X64_CC_FLAGS = DEF(GCC49_X64_CC_FLAGS) -O0 >> >> ################## >> @@ -5240,7 +5240,7 @@ RELEASE_GCC49_X64_CC_FLAGS = >> DEF(GCC49_X64_CC_FLAGS) -Os -Wno-unused-but-s >> *_GCC49_ARM_CC_XIPFLAGS = DEF(GCC49_ARM_CC_XIPFLAGS) >> >> DEBUG_GCC49_ARM_CC_FLAGS = DEF(GCC49_ARM_CC_FLAGS) -O0 >> -RELEASE_GCC49_ARM_CC_FLAGS = DEF(GCC49_ARM_CC_FLAGS) >> -Wno-unused-but-set-variable >> +RELEASE_GCC49_ARM_CC_FLAGS = DEF(GCC49_ARM_CC_FLAGS) >> -Wno-unused-but-set-variable -Wno-unused-const-variable >> NOOPT_GCC49_ARM_CC_FLAGS = DEF(GCC49_ARM_CC_FLAGS) -O0 >> >> ################## >> @@ -5272,7 +5272,7 @@ RELEASE_GCC49_ARM_CC_FLAGS = >> DEF(GCC49_ARM_CC_FLAGS) -Wno-unused-but-set-v >> DEBUG_GCC49_AARCH64_DLINK_FLAGS = DEF(GCC49_AARCH64_DLINK_FLAGS) -z >> common-page-size=0x1000 >> DEBUG_GCC49_AARCH64_DLINK_XIPFLAGS = -z common-page-size=0x20 >> >> -RELEASE_GCC49_AARCH64_CC_FLAGS = DEF(GCC49_AARCH64_CC_FLAGS) >> -Wno-unused-but-set-variable -mcmodel=tiny -fomit-frame-pointer >> +RELEASE_GCC49_AARCH64_CC_FLAGS = DEF(GCC49_AARCH64_CC_FLAGS) >> -Wno-unused-but-set-variable -Wno-unused-const-variable -mcmodel=tiny >> -fomit-frame-pointer >> RELEASE_GCC49_AARCH64_DLINK_FLAGS = DEF(GCC49_AARCH64_DLINK_FLAGS) >> >> NOOPT_GCC49_AARCH64_CC_FLAGS = DEF(GCC49_AARCH64_CC_FLAGS) -O0 >> -mcmodel=small >> @@ -5326,7 +5326,7 @@ RELEASE_GCC49_AARCH64_DLINK_FLAGS = >> DEF(GCC49_AARCH64_DLINK_FLAGS) >> DEBUG_GCC5_IA32_CC_FLAGS = DEF(GCC5_IA32_CC_FLAGS) -flto -Os >> DEBUG_GCC5_IA32_DLINK_FLAGS = DEF(GCC5_IA32_X64_DLINK_FLAGS) -flto -Os >> -Wl,-m,elf_i386,--oformat=elf32-i386 >> >> -RELEASE_GCC5_IA32_CC_FLAGS = DEF(GCC5_IA32_CC_FLAGS) -flto -Os >> -Wno-unused-but-set-variable >> +RELEASE_GCC5_IA32_CC_FLAGS = DEF(GCC5_IA32_CC_FLAGS) -flto -Os >> -Wno-unused-but-set-variable -Wno-unused-const-variable >> RELEASE_GCC5_IA32_DLINK_FLAGS = DEF(GCC5_IA32_X64_DLINK_FLAGS) -flto -Os >> -Wl,-m,elf_i386,--oformat=elf32-i386 >> >> NOOPT_GCC5_IA32_CC_FLAGS = DEF(GCC5_IA32_CC_FLAGS) -O0 >> @@ -5358,7 +5358,7 @@ RELEASE_GCC5_IA32_DLINK_FLAGS = >> DEF(GCC5_IA32_X64_DLINK_FLAGS) -flto -Os -Wl, >> DEBUG_GCC5_X64_CC_FLAGS = DEF(GCC5_X64_CC_FLAGS) -flto -DUSING_LTO >> -Os >> DEBUG_GCC5_X64_DLINK_FLAGS = DEF(GCC5_X64_DLINK_FLAGS) -flto -Os >> >> -RELEASE_GCC5_X64_CC_FLAGS = DEF(GCC5_X64_CC_FLAGS) -flto -DUSING_LTO >> -Os -Wno-unused-but-set-variable >> +RELEASE_GCC5_X64_CC_FLAGS = DEF(GCC5_X64_CC_FLAGS) -flto -DUSING_LTO >> -Os -Wno-unused-but-set-variable -Wno-unused-const-variable >> RELEASE_GCC5_X64_DLINK_FLAGS = DEF(GCC5_X64_DLINK_FLAGS) -flto -Os >> >> NOOPT_GCC5_X64_CC_FLAGS = DEF(GCC5_X64_CC_FLAGS) -O0 >> @@ -5393,7 +5393,7 @@ RELEASE_GCC5_X64_DLINK_FLAGS = >> DEF(GCC5_X64_DLINK_FLAGS) -flto -Os >> DEBUG_GCC5_ARM_CC_FLAGS = DEF(GCC5_ARM_CC_FLAGS) -O0 >> DEBUG_GCC5_ARM_DLINK_FLAGS = DEF(GCC5_ARM_DLINK_FLAGS) >> >> -RELEASE_GCC5_ARM_CC_FLAGS = DEF(GCC5_ARM_CC_FLAGS) -flto >> -Wno-unused-but-set-variable >> +RELEASE_GCC5_ARM_CC_FLAGS = DEF(GCC5_ARM_CC_FLAGS) -flto >> -Wno-unused-but-set-variable -Wno-unused-const-variable >> RELEASE_GCC5_ARM_DLINK_FLAGS = DEF(GCC5_ARM_DLINK_FLAGS) -flto -Os >> -L$(WORKSPACE)/ArmPkg/Library/GccLto -llto-arm >> -Wl,-plugin-opt=-pass-through=-llto-arm >> >> NOOPT_GCC5_ARM_CC_FLAGS = DEF(GCC5_ARM_CC_FLAGS) -O0 >> @@ -5428,7 +5428,7 @@ RELEASE_GCC5_ARM_DLINK_FLAGS = >> DEF(GCC5_ARM_DLINK_FLAGS) -flto -Os -L$(WORKS >> DEBUG_GCC5_AARCH64_DLINK_FLAGS = DEF(GCC5_AARCH64_DLINK_FLAGS) -z >> common-page-size=0x1000 >> DEBUG_GCC5_AARCH64_DLINK_XIPFLAGS = -z common-page-size=0x20 >> >> -RELEASE_GCC5_AARCH64_CC_FLAGS = DEF(GCC5_AARCH64_CC_FLAGS) -flto >> -Wno-unused-but-set-variable -mcmodel=tiny -fomit-frame-pointer >> +RELEASE_GCC5_AARCH64_CC_FLAGS = DEF(GCC5_AARCH64_CC_FLAGS) -flto >> -Wno-unused-but-set-variable -Wno-unused-const-variable -mcmodel=tiny >> -fomit-frame-pointer >> RELEASE_GCC5_AARCH64_DLINK_FLAGS = DEF(GCC5_AARCH64_DLINK_FLAGS) -flto -Os >> -L$(WORKSPACE)/ArmPkg/Library/GccLto -llto-aarch64 >> -Wl,-plugin-opt=-pass-through=-llto-aarch64 -Wno-lto-type-mismatch >> >> NOOPT_GCC5_AARCH64_CC_FLAGS = DEF(GCC5_AARCH64_CC_FLAGS) -O0 >> -mcmodel=small >> > > > Reviewed-by: Laszlo Ersek <[email protected]> _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
