[Bug c/57657] New: [regression from 4.7] Reports incorrect cache sizes on corei7

["thomas dot braun at virtuell-zuhause dot de" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57657

            Bug ID: 57657
           Summary: [regression from 4.7] Reports incorrect cache sizes on
                    corei7
           Product: gcc
           Version: 4.8.1
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: thomas.braun@virtuell-zuhause.de

I have a "Intel(R) Core(TM) i7-3930K CPU @ 3.20GH" CPU and I'm on debian
unstable.

The bottom line is that gcc-4.8 reports incorrect cache sizes compared to
gcc-4.7.

#gcc-4.8 -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.8/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 4.8.1-3'
--with-bugurl=file:///usr/share/doc/gcc-4.8/README.Bugs
--enable-languages=c,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-4.8 --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--with-gxx-include-dir=/usr/include/c++/4.8 --libdir=/usr/lib --enable-nls
--with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug
--enable-libstdcxx-time=yes --enable-gnu-unique-object --enable-plugin
--with-system-zlib --disable-browser-plugin --enable-java-awt=gtk
--enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64/jre
--enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64
--with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-4.8-amd64
--with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar
--enable-objc-gc --enable-multiarch --with-arch-32=i586 --with-abi=m64
--with-multilib-list=m32,m64,mx32 --with-tune=generic --enable-checking=release
--build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.8.1 (Debian 4.8.1-3) 

Calling
#gcc-4.8 -### -E -march=native /usr/include/stdlib.h 2>&1 | grep cache-size
gives
 /usr/lib/gcc/x86_64-linux-gnu/4.8/cc1 -E -quiet -imultilib . -imultiarch
x86_64-linux-gnu /usr/include/stdlib.h "-march=corei7-avx" -mcx16 -msahf
-mno-movbe -maes -mpclmul -mpopcnt -mno-abm -mno-lwp -mno-fma -mno-fma4
-mno-xop -mno-bmi -mno-bmi2 -mno-tbm -mavx -mno-avx2 -msse4.2 -msse4.1
-mno-lzcnt -mno-rtm -mno-hle -mno-rdrnd -mno-f16c -mno-fsgsbase -mno-rdseed
-mno-prfchw -mno-adx -mfxsr -mxsave -mxsaveopt --param "l1-cache-size=0"
--param "l1-cache-line-size=0" --param "l2-cache-size=256" "-mtune=corei7-avx"

Whereas
#cat /proc/cpuinfo | grep -E "(cache size|cache_alignment)" | tail -n 2
says
cache size      : 12288 KB
cache_alignment : 64

Using an older version of gcc
#gcc-4.7 --version
gcc-4.7 (Debian 4.7.3-5) 4.7.3
Copyright (C) 2012 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE

I get what I expect
#gcc-4.7 -### -E -march=native /usr/include/stdlib.h 2>&1 | grep cache-size
 /usr/lib/gcc/x86_64-linux-gnu/4.7/cc1 -E -quiet -imultilib . -imultiarch
x86_64-linux-gnu /usr/include/stdlib.h "-march=corei7-avx" -mcx16 -msahf
-mno-movbe -maes -mpclmul -mpopcnt -mno-abm -mno-lwp -mno-fma -mno-fma4
-mno-xop -mno-bmi -mno-bmi2 -mno-tbm -mavx -mno-avx2 -msse4.2 -msse4.1
-mno-lzcnt -mno-rdrnd -mno-f16c -mno-fsgsbase --param "l1-cache-size=32"
--param "l1-cache-line-size=64" --param "l2-cache-size=12288"
"-mtune=corei7-avx

Thanks for reading
Thomas

PS: Output of cpuid
 eax in    eax      ebx      ecx      edx
00000000 0000000d 756e6547 6c65746e 49656e69
00000001 000206d7 03200800 1fbee3bf bfebfbff
00000002 76035a01 00f0b2ff 00000000 00ca0000
00000003 00000000 00000000 00000000 00000000
00000004 00000000 00000000 00000000 00000000
00000005 00000040 00000040 00000003 00021120
00000006 00000077 00000002 00000009 00000000
00000007 00000000 00000000 00000000 00000000
00000008 00000000 00000000 00000000 00000000
00000009 00000001 00000000 00000000 00000000
0000000a 07300403 00000000 00000000 00000603
0000000b 00000000 00000000 0000002c 00000003
0000000c 00000000 00000000 00000000 00000000
0000000d 00000000 00000000 00000000 00000000
80000000 80000008 00000000 00000000 00000000
80000001 00000000 00000000 00000001 2c100800
80000002 20202020 49202020 6c65746e 20295228
80000003 65726f43 294d5428 2d376920 30333933
80000004 5043204b 20402055 30322e33 007a4847
80000005 00000000 00000000 00000000 00000000
80000006 00000000 00000000 01006040 00000000
80000007 00000000 00000000 00000000 00000100
80000008 0000302e 00000000 00000000 00000000

Vendor ID: "GenuineIntel"; CPUID level 13

Intel-specific functions:
Version 000206d7:
Type 0 - Original OEM
Family 6 - Pentium Pro
Model 13 - 
Stepping 7
Reserved 8

Extended brand string: "       Intel(R) Core(TM) i7-3930K CPU @ 3.20GHz"
CLFLUSH instruction cache line size: 8
Initial APIC ID: 3
Hyper threading siblings: 32

Feature flags bfebfbff:
FPU    Floating Point Unit
VME    Virtual 8086 Mode Enhancements
DE     Debugging Extensions
PSE    Page Size Extensions
TSC    Time Stamp Counter
MSR    Model Specific Registers
PAE    Physical Address Extension
MCE    Machine Check Exception
CX8    COMPXCHG8B Instruction
APIC   On-chip Advanced Programmable Interrupt Controller present and enabled
SEP    Fast System Call
MTRR   Memory Type Range Registers
PGE    PTE Global Flag
MCA    Machine Check Architecture
CMOV   Conditional Move and Compare Instructions
FGPAT  Page Attribute Table
PSE-36 36-bit Page Size Extension
CLFSH  CFLUSH instruction
DS     Debug store
ACPI   Thermal Monitor and Clock Ctrl
MMX    MMX instruction set
FXSR   Fast FP/MMX Streaming SIMD Extensions save/restore
SSE    Streaming SIMD Extensions instruction set
SSE2   SSE2 extensions
SS     Self Snoop
HT     Hyper Threading
TM     Thermal monitor
31     reserved

TLB and cache info:
5a: unknown TLB/cache descriptor
03: Data TLB: 4KB pages, 4-way set assoc, 64 entries
76: unknown TLB/cache descriptor
ff: unknown TLB/cache descriptor
b2: unknown TLB/cache descriptor
f0: unknown TLB/cache descriptor
ca: unknown TLB/cache descriptor
Processor serial: XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX