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[RS6000] -mno-minimal-toc vs. power10 pcrelative

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We've had this hack in the libgcc config to build libgcc with
-mcmodel=small for powerpc64 for a long time.  It wouldn't be a bad
thing if someone who knows the multilib machinery well could arrange
for -mcmodel=small to be passed just for ppc64 when building for
earlier than power10.  But for now, make -mno-minimal-toc do nothing
when pcrel.  Which will do the right thing for any project that has
copied libgcc's trick.

We want this if configuring using --with-cpu=power10 to build a
power10 pcrel libgcc.  --mcmodel=small turns off pcrel.

gcc/
	* config/rs6000/linux64.h (SUBSUBTARGET_OVERRIDE_OPTIONS): Don't
	set -mcmodel=small for -mno-minimal-toc when pcrel.
libgcc/
	* config/rs6000/t-linux: Document purpose of -mno-minimal-toc.
This commit is contained in:
Alan Modra 2020-09-28 16:23:01 +09:30
parent cf7dae0173
commit c6be439b37
2 changed files with 19 additions and 5 deletions
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17
gcc/config/rs6000/linux64.h
View File

@ -132,20 +132,29 @@ extern int dot_symbols;
if ((rs6000_isa_flags & OPTION_MASK_POWERPC64) == 0) \
{ \
rs6000_isa_flags |= OPTION_MASK_POWERPC64; \
error ("%<-m64%> requires a PowerPC64 cpu"); \
error ("%<-m64%> requires a PowerPC64 cpu"); \
} \
if (!global_options_set.x_rs6000_current_cmodel) \
SET_CMODEL (CMODEL_MEDIUM); \
if ((rs6000_isa_flags_explicit \
& OPTION_MASK_MINIMAL_TOC) != 0) \
{ \
if (global_options_set.x_rs6000_current_cmodel \
&& rs6000_current_cmodel != CMODEL_SMALL) \
error ("%<-mcmodel incompatible with other toc options%>"); \
SET_CMODEL (CMODEL_SMALL); \
if (TARGET_MINIMAL_TOC) \
SET_CMODEL (CMODEL_SMALL); \
else if (TARGET_PCREL \
|| (PCREL_SUPPORTED_BY_OS \
&& (rs6000_isa_flags_explicit \
& OPTION_MASK_PCREL) == 0)) \
/* Ignore -mno-minimal-toc. */ \
; \
else \
SET_CMODEL (CMODEL_SMALL); \
} \
else \
{ \
if (!global_options_set.x_rs6000_current_cmodel) \
SET_CMODEL (CMODEL_MEDIUM); \
if (rs6000_current_cmodel != CMODEL_SMALL) \
{ \
if (!global_options_set.x_TARGET_NO_FP_IN_TOC) \

7
libgcc/config/rs6000/t-linux
View File

@ -1,3 +1,8 @@
SHLIB_MAPFILES += $(srcdir)/config/rs6000/libgcc-glibc.ver
HOST_LIBGCC2_CFLAGS += -mlong-double-128 -mno-minimal-toc
HOST_LIBGCC2_CFLAGS += -mlong-double-128
# This is a way of selecting -mcmodel=small for ppc64, which gives
# smaller and faster libgcc code. Directly specifying -mcmodel=small
# would need to take into account targets for which -mcmodel is invalid.
HOST_LIBGCC2_CFLAGS += -mno-minimal-toc