Re: CVS commit: src/sys/arch
On Wed, Feb 05, 2014 at 11:43:21PM +, David Laight wrote: > On Wed, Feb 05, 2014 at 03:09:59PM -0800, Matt Thomas wrote: > > > > >> > > >> This breaks clang. Please do not depend on one SSE option disabling > > >> another. > > > > > > Without those flags I believe gcc might generate x87 instructions. > > > Quite possibly even for amd64. > > > See a very recent linux fix. > > > Try searching for: Disable generation of traditional x87 instructions > > > > I think Joerg is saying put in -mno-sse2 since that is not disabled > > by -mno-sse when using clang. > > with the gcc I'm looking at (if I'm reading to code properly): > no-sse => no-sse2 => no-sse3 => no-ssse3 & no-sse4a => no-sse4_1 > => no-sse4_2 => no-avx => no-fma => no-fma4 While I mostly believe that -mno-sse will imply -mno-sse2, it is the one I want to be explicit about since it is default feature of the amd64 platform. Joerg
Re: CVS commit: src/sys/arch
On Feb 5, 2014, at 3:43 PM, David Laight wrote: > On Wed, Feb 05, 2014 at 03:09:59PM -0800, Matt Thomas wrote: >> This breaks clang. Please do not depend on one SSE option disabling another. >>> >>> Without those flags I believe gcc might generate x87 instructions. >>> Quite possibly even for amd64. >>> See a very recent linux fix. >>> Try searching for: Disable generation of traditional x87 instructions >> >> I think Joerg is saying put in -mno-sse2 since that is not disabled >> by -mno-sse when using clang. > > with the gcc I'm looking at (if I'm reading to code properly): > no-sse => no-sse2 => no-sse3 => no-ssse3 & no-sse4a => no-sse4_1 > => no-sse4_2 => no-avx => no-fma => no-fma4 But clang is not gcc. :) > You either need all of them, and the one that the next sub-version > of the cpu/compiler add, or you assume that the first ones imply the > latter - at least to some degree. From llvm/dist/llvm/lib/Target/X86/X86.td: // All x86-64 hardware has SSE2, but we don't mark SSE2 as an implied // feature, because SSE2 can be disabled (e.g. for compiling OS kernels) // without disabling 64-bit mode.
Re: CVS commit: src/sys/arch
On Wed, Feb 05, 2014 at 03:09:59PM -0800, Matt Thomas wrote: > > >> > >> This breaks clang. Please do not depend on one SSE option disabling > >> another. > > > > Without those flags I believe gcc might generate x87 instructions. > > Quite possibly even for amd64. > > See a very recent linux fix. > > Try searching for: Disable generation of traditional x87 instructions > > I think Joerg is saying put in -mno-sse2 since that is not disabled > by -mno-sse when using clang. with the gcc I'm looking at (if I'm reading to code properly): no-sse => no-sse2 => no-sse3 => no-ssse3 & no-sse4a => no-sse4_1 => no-sse4_2 => no-avx => no-fma => no-fma4 You either need all of them, and the one that the next sub-version of the cpu/compiler add, or you assume that the first ones imply the latter - at least to some degree. David -- David Laight: da...@l8s.co.uk
Re: CVS commit: src/sys/arch
On Feb 5, 2014, at 3:06 PM, David Laight wrote: > On Wed, Feb 05, 2014 at 11:09:05PM +0100, Joerg Sonnenberger wrote: >> On Wed, Feb 05, 2014 at 06:52:22PM +, David Laight wrote: >>> Module Name:src >>> Committed By: dsl >>> Date: Wed Feb 5 18:52:22 UTC 2014 >>> >>> Modified Files: >>> src/sys/arch/amd64/conf: Makefile.amd64 >>> src/sys/arch/i386/conf: Makefile.i386 >>> >>> Log Message: >>> Change the compiler options to explicitly specify: >>> -mno-mmx -mno-sse -mno-avx -mno-80387 -mno-fp-ret-in-387 >>> Since no-sse implies no-sse2 that should ensure that the compiler really >>> doesn't emit any instructions that might trap trying to use the FPU. >>> On amd64 at least some of those are needed to stop the compiler >>> saving the registers to stack on every varargs function. >>> It might be that -mno-sse did that before. >> >> This breaks clang. Please do not depend on one SSE option disabling >> another. > > Without those flags I believe gcc might generate x87 instructions. > Quite possibly even for amd64. > See a very recent linux fix. > Try searching for: Disable generation of traditional x87 instructions I think Joerg is saying put in -mno-sse2 since that is not disabled by -mno-sse when using clang.
Re: CVS commit: src/sys/arch
On Wed, Feb 05, 2014 at 11:09:05PM +0100, Joerg Sonnenberger wrote: > On Wed, Feb 05, 2014 at 06:52:22PM +, David Laight wrote: > > Module Name:src > > Committed By: dsl > > Date: Wed Feb 5 18:52:22 UTC 2014 > > > > Modified Files: > > src/sys/arch/amd64/conf: Makefile.amd64 > > src/sys/arch/i386/conf: Makefile.i386 > > > > Log Message: > > Change the compiler options to explicitly specify: > > -mno-mmx -mno-sse -mno-avx -mno-80387 -mno-fp-ret-in-387 > > Since no-sse implies no-sse2 that should ensure that the compiler really > > doesn't emit any instructions that might trap trying to use the FPU. > > On amd64 at least some of those are needed to stop the compiler > > saving the registers to stack on every varargs function. > > It might be that -mno-sse did that before. > > This breaks clang. Please do not depend on one SSE option disabling > another. Without those flags I believe gcc might generate x87 instructions. Quite possibly even for amd64. See a very recent linux fix. Try searching for: Disable generation of traditional x87 instructions David -- David Laight: da...@l8s.co.uk
Re: CVS commit: src/sys/arch
On Wed, Feb 05, 2014 at 06:52:22PM +, David Laight wrote: > Module Name: src > Committed By: dsl > Date: Wed Feb 5 18:52:22 UTC 2014 > > Modified Files: > src/sys/arch/amd64/conf: Makefile.amd64 > src/sys/arch/i386/conf: Makefile.i386 > > Log Message: > Change the compiler options to explicitly specify: > -mno-mmx -mno-sse -mno-avx -mno-80387 -mno-fp-ret-in-387 > Since no-sse implies no-sse2 that should ensure that the compiler really > doesn't emit any instructions that might trap trying to use the FPU. > On amd64 at least some of those are needed to stop the compiler > saving the registers to stack on every varargs function. > It might be that -mno-sse did that before. This breaks clang. Please do not depend on one SSE option disabling another. Joerg
