* Re: [PATCH, MIPS] -mno-float odds and ends
2012-07-30 19:39 ` Richard Sandiford
@ 2012-07-30 21:55 ` Sandra Loosemore
2012-07-30 22:27 ` Sandra Loosemore
1 sibling, 0 replies; 4+ messages in thread
From: Sandra Loosemore @ 2012-07-30 21:55 UTC (permalink / raw)
To: gcc-patches, rdsandiford
[-- Attachment #1: Type: text/plain, Size: 2108 bytes --]
On 07/30/2012 01:38 PM, Richard Sandiford wrote:
>
> ...unfortunately, it doesn't prevent the use floating-point operations.
> That's why it's such a bad option. The only difference from the compiler
> proper's point of view between -msoft-float and -mno-float is that they
> define different preprocessor macros.
>
> The onus is instead on the programmer to avoid writing anything that
> might tempt the compiler into using floating-point operations. If the
> user gets it wrong, they get (at best) a link-time error rather than a
> compile-time error.
>
> I think we should document it that way. E.g. something like:
>
> @item -mno-float
> @opindex mno-float
> Equivalent to @option{-msoft-float}, but asserts that the user is
> trying to avoid all floating-point operations. This option is presently
> supported only by some bare-metal MIPS configurations, where it selects
> a special set of libraries that lack all floating-point support
> (including, for example, the floating-point @code{printf} formats).
> If code compiled with @code{-mno-float} accidentally contains
> floating-point operations, it is likely to suffer a link-time
> or run-time failure.
>
> but you're better at the wordsmithing than I am.
OK, I've gone with a slightly tweaked version of your wording.
> Perhaps we should document the __mips_no_float preprocessor macro too,
> since that's how things like printf() know that they don't need the
> floating-point stuff.
Hmmm, I don't think that's necessary, at least as part of this patch; we
don't document the related __mips_hard_float or __mips_soft_float
preprocessor definitions, either.
> The mips.h part is OK though, thanks. Feel free to apply it separately
> if that's more convenient than keeping the patch together.
I've checked in the attached version of the patch. Thanks for the
speedy review! :-)
-Sandra
2012-07-30 Sandra Loosemore <sandra@codesourcery.com>
Julian Brown <julian@codesourcery.com>
gcc/
* doc/invoke.texi (MIPS Options): Document -mno-float.
* config/mips/mips.h (MIPS_ARCH_FLOAT_SPEC): Make it know
about -mno-float.
[-- Attachment #2: no-float.patch --]
[-- Type: text/x-patch, Size: 2102 bytes --]
Index: gcc/doc/invoke.texi
===================================================================
--- gcc/doc/invoke.texi (revision 189950)
+++ gcc/doc/invoke.texi (working copy)
@@ -733,7 +733,8 @@ Objective-C and Objective-C++ Dialects}.
-mabi=@var{abi} -mabicalls -mno-abicalls @gol
-mshared -mno-shared -mplt -mno-plt -mxgot -mno-xgot @gol
-mgp32 -mgp64 -mfp32 -mfp64 -mhard-float -msoft-float @gol
--msingle-float -mdouble-float -mdsp -mno-dsp -mdspr2 -mno-dspr2 @gol
+-mno-float -msingle-float -mdouble-float @gol
+-mdsp -mno-dsp -mdspr2 -mno-dspr2 @gol
-mmcu -mmno-mcu @gol
-mfpu=@var{fpu-type} @gol
-msmartmips -mno-smartmips @gol
@@ -15633,6 +15634,18 @@ Use floating-point coprocessor instructi
Do not use floating-point coprocessor instructions. Implement
floating-point calculations using library calls instead.
+@item -mno-float
+@opindex mno-float
+Equivalent to @option{-msoft-float}, but additionally asserts that the
+program being compiled does not perform any floating-point operations.
+This option is presently supported only by some bare-metal MIPS
+configurations, where it may select a special set of libraries
+that lack all floating-point support (including, for example, the
+floating-point @code{printf} formats).
+If code compiled with @code{-mno-float} accidentally contains
+floating-point operations, it is likely to suffer a link-time
+or run-time failure.
+
@item -msingle-float
@opindex msingle-float
Assume that the floating-point coprocessor only supports single-precision
Index: gcc/config/mips/mips.h
===================================================================
--- gcc/config/mips/mips.h (revision 189950)
+++ gcc/config/mips/mips.h (working copy)
@@ -713,7 +713,7 @@ struct mips_cpu_info {
link-compatible. */
#define MIPS_ARCH_FLOAT_SPEC \
- "%{mhard-float|msoft-float|march=mips*:; \
+ "%{mhard-float|msoft-float|mno-float|march=mips*:; \
march=vr41*|march=m4k|march=4k*|march=24kc|march=24kec \
|march=34kc|march=74kc|march=1004kc|march=5kc \
|march=octeon|march=xlr: -msoft-float; \
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH, MIPS] -mno-float odds and ends
2012-07-30 19:39 ` Richard Sandiford
2012-07-30 21:55 ` Sandra Loosemore
@ 2012-07-30 22:27 ` Sandra Loosemore
1 sibling, 0 replies; 4+ messages in thread
From: Sandra Loosemore @ 2012-07-30 22:27 UTC (permalink / raw)
To: gcc-patches, rdsandiford
[-- Attachment #1: Type: text/plain, Size: 2108 bytes --]
On 07/30/2012 01:38 PM, Richard Sandiford wrote:
>
> ...unfortunately, it doesn't prevent the use floating-point operations.
> That's why it's such a bad option. The only difference from the compiler
> proper's point of view between -msoft-float and -mno-float is that they
> define different preprocessor macros.
>
> The onus is instead on the programmer to avoid writing anything that
> might tempt the compiler into using floating-point operations. If the
> user gets it wrong, they get (at best) a link-time error rather than a
> compile-time error.
>
> I think we should document it that way. E.g. something like:
>
> @item -mno-float
> @opindex mno-float
> Equivalent to @option{-msoft-float}, but asserts that the user is
> trying to avoid all floating-point operations. This option is presently
> supported only by some bare-metal MIPS configurations, where it selects
> a special set of libraries that lack all floating-point support
> (including, for example, the floating-point @code{printf} formats).
> If code compiled with @code{-mno-float} accidentally contains
> floating-point operations, it is likely to suffer a link-time
> or run-time failure.
>
> but you're better at the wordsmithing than I am.
OK, I've gone with a slightly tweaked version of your wording.
> Perhaps we should document the __mips_no_float preprocessor macro too,
> since that's how things like printf() know that they don't need the
> floating-point stuff.
Hmmm, I don't think that's necessary, at least as part of this patch; we
don't document the related __mips_hard_float or __mips_soft_float
preprocessor definitions, either.
> The mips.h part is OK though, thanks. Feel free to apply it separately
> if that's more convenient than keeping the patch together.
I've checked in the attached version of the patch. Thanks for the
speedy review! :-)
-Sandra
2012-07-30 Sandra Loosemore <sandra@codesourcery.com>
Julian Brown <julian@codesourcery.com>
gcc/
* doc/invoke.texi (MIPS Options): Document -mno-float.
* config/mips/mips.h (MIPS_ARCH_FLOAT_SPEC): Make it know
about -mno-float.
[-- Attachment #2: no-float.patch --]
[-- Type: text/x-patch, Size: 2102 bytes --]
Index: gcc/doc/invoke.texi
===================================================================
--- gcc/doc/invoke.texi (revision 189950)
+++ gcc/doc/invoke.texi (working copy)
@@ -733,7 +733,8 @@ Objective-C and Objective-C++ Dialects}.
-mabi=@var{abi} -mabicalls -mno-abicalls @gol
-mshared -mno-shared -mplt -mno-plt -mxgot -mno-xgot @gol
-mgp32 -mgp64 -mfp32 -mfp64 -mhard-float -msoft-float @gol
--msingle-float -mdouble-float -mdsp -mno-dsp -mdspr2 -mno-dspr2 @gol
+-mno-float -msingle-float -mdouble-float @gol
+-mdsp -mno-dsp -mdspr2 -mno-dspr2 @gol
-mmcu -mmno-mcu @gol
-mfpu=@var{fpu-type} @gol
-msmartmips -mno-smartmips @gol
@@ -15633,6 +15634,18 @@ Use floating-point coprocessor instructi
Do not use floating-point coprocessor instructions. Implement
floating-point calculations using library calls instead.
+@item -mno-float
+@opindex mno-float
+Equivalent to @option{-msoft-float}, but additionally asserts that the
+program being compiled does not perform any floating-point operations.
+This option is presently supported only by some bare-metal MIPS
+configurations, where it may select a special set of libraries
+that lack all floating-point support (including, for example, the
+floating-point @code{printf} formats).
+If code compiled with @code{-mno-float} accidentally contains
+floating-point operations, it is likely to suffer a link-time
+or run-time failure.
+
@item -msingle-float
@opindex msingle-float
Assume that the floating-point coprocessor only supports single-precision
Index: gcc/config/mips/mips.h
===================================================================
--- gcc/config/mips/mips.h (revision 189950)
+++ gcc/config/mips/mips.h (working copy)
@@ -713,7 +713,7 @@ struct mips_cpu_info {
link-compatible. */
#define MIPS_ARCH_FLOAT_SPEC \
- "%{mhard-float|msoft-float|march=mips*:; \
+ "%{mhard-float|msoft-float|mno-float|march=mips*:; \
march=vr41*|march=m4k|march=4k*|march=24kc|march=24kec \
|march=34kc|march=74kc|march=1004kc|march=5kc \
|march=octeon|march=xlr: -msoft-float; \
^ permalink raw reply [flat|nested] 4+ messages in thread