diff mbox

[V3] When disabling SSE, make sure -fpmath is not set to use SSE either

Message ID 1459439112-30153-1-git-send-email-raj.khem@gmail.com
State New, archived
Headers

Commit Message

Khem Raj March 31, 2016, 3:45 p.m. UTC 
  This fixes errors when we inject sse options through CFLAGS and now
that we have -Werror turned on by default this warning turns to become
error on x86

gcc -m32 -march=core2 -mtune=core2 -msse3 -mfpmath=sse -x c /dev/null -S
-mno-sse -mno-mmx

generates warning
/dev/null:1:0: warning: SSE instruction set disabled, using 387
arithmetics

where as

gcc -m32 -march=core2 -mtune=core2 -msse3 -mfpmath=sse -x c /dev/null -S
-mno-sse -mno-mmx -mfpmath=387

Generates no warnings

Signed-off-by: Khem Raj <raj.khem@gmail.com>
---
Changes since v1:
- Add BZ enry to ChangeLog and commit message

Changes since v2:
- Add commentary in makefile, describing why the change is needed

 ChangeLog             | 6 ++++++
 sysdeps/i386/Makefile | 6 +++++-
 2 files changed, 11 insertions(+), 1 deletion(-)

Comments

Mike Frysinger April 3, 2016, 2:16 a.m. UTC | #1 
On 31 Mar 2016 08:45, Khem Raj wrote:
>  # Make sure no code in ld.so uses mm/xmm/ymm/zmm registers on i386 since
>  # the first 3 mm/xmm/ymm/zmm registers are used to pass vector parameters
>  # which must be preserved.
> +# with SSE disabled, ensure -fpmath is not set to use sse either, this
> +# avoids below compiler diagnostic
> +# warning: SSE instruction set disabled, using 387 arithmetics
> +# which is treated as error with -Werror

the flag change looks fine, but this comment seems excessive.
i think it should just read:
# With SSE disabled, ensure -fpmath is not set to use sse either.
-mike
diff mbox

Patch

diff --git a/ChangeLog b/ChangeLog
index 4fc73b1..6d2fd80 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@ 
+2016-03-31  Khem Raj  <raj.khem@gmail.com>
+
+	[BZ #17950]
+	* sysdeps/i386/Makefile [$(subdir) == elf] (CFLAGS-.os):
+	Add -mfpmath=387.
+
 2016-03-31  Adhemerval Zanella  <adhemerval.zanella@linaro.org>
 
 	* elf/tst-dlsym-error.c: Include <string.h> for strchrnul.
diff --git a/sysdeps/i386/Makefile b/sysdeps/i386/Makefile
index 168512f..929b377 100644
--- a/sysdeps/i386/Makefile
+++ b/sysdeps/i386/Makefile
@@ -88,8 +88,12 @@  ifeq ($(subdir),elf)
 # Make sure no code in ld.so uses mm/xmm/ymm/zmm registers on i386 since
 # the first 3 mm/xmm/ymm/zmm registers are used to pass vector parameters
 # which must be preserved.
+# with SSE disabled, ensure -fpmath is not set to use sse either, this
+# avoids below compiler diagnostic
+# warning: SSE instruction set disabled, using 387 arithmetics
+# which is treated as error with -Werror
 CFLAGS-.os += $(if $(filter $(@F),$(patsubst %,%.os,$(all-rtld-routines))),\
-		   -mno-sse -mno-mmx)
+		   -mno-sse -mno-mmx -mfpmath=387)
 
 tests-special += $(objpfx)tst-ld-sse-use.out
 $(objpfx)tst-ld-sse-use.out: ../sysdeps/i386/tst-ld-sse-use.sh $(objpfx)ld.so