[PATCH] D46323: [compiler-rt][X86][AMD][Bulldozer] Fix Bulldozer Model 2 detection.

Roman Lebedev via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Tue May 1 10:08:02 PDT 2018


lebedev.ri created this revision.
lebedev.ri added reviewers: craig.topper, asbirlea, rnk, GGanesh, andreadb.
Herald added subscribers: Sanitizers, JDevlieghere, arichardson, aprantl, dberris, sdardis.

The compiler-rt side of https://reviews.llvm.org/D46314

I have discovered an issue by accident.

  $ lscpu 
  Architecture:        x86_64
  CPU op-mode(s):      32-bit, 64-bit
  Byte Order:          Little Endian
  CPU(s):              8
  On-line CPU(s) list: 0-7
  Thread(s) per core:  2
  Core(s) per socket:  4
  Socket(s):           1
  NUMA node(s):        1
  Vendor ID:           AuthenticAMD
  CPU family:          21
  Model:               2
  Model name:          AMD FX(tm)-8350 Eight-Core Processor
  Stepping:            0
  CPU MHz:             3584.018
  CPU max MHz:         4000.0000
  CPU min MHz:         1400.0000
  BogoMIPS:            8027.22
  Virtualization:      AMD-V
  L1d cache:           16K
  L1i cache:           64K
  L2 cache:            2048K
  L3 cache:            8192K
  NUMA node0 CPU(s):   0-7
  Flags:               fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm constant_tsc rep_good nopl nonstop_tsc cpuid extd_apicid aperfmperf pni pclmulqdq monitor ssse3 fma cx16 sse4_1 sse4_2 popcnt aes xsave avx f16c lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs xop skinit wdt lwp fma4 tce nodeid_msr tbm topoext perfctr_core perfctr_nb cpb hw_pstate vmmcall bmi1 arat npt lbrv svm_lock nrip_save tsc_scale vmcb_clean flushbyasid decodeassists pausefilter pfthreshold

So this is model-2 bulldozer AMD CPU.

GCC agrees:

  $ echo | gcc -E - -march=native -###
  <...>
   /usr/lib/gcc/x86_64-linux-gnu/7/cc1 -E -quiet -imultiarch x86_64-linux-gnu - "-march=bdver2" -mmmx -mno-3dnow -msse -msse2 -msse3 -mssse3 -msse4a -mcx16 -msahf -mno-movbe -maes -mno-sha -mpclmul -mpopcnt -mabm -mlwp -mfma -mfma4 -mxop -mbmi -mno-sgx -mno-bmi2 -mtbm -mavx -mno-avx2 -msse4.2 -msse4.1 -mlzcnt -mno-rtm -mno-hle -mno-rdrnd -mf16c -mno-fsgsbase -mno-rdseed -mprfchw -mno-adx -mfxsr -mxsave -mno-xsaveopt -mno-avx512f -mno-avx512er -mno-avx512cd -mno-avx512pf -mno-prefetchwt1 -mno-clflushopt -mno-xsavec -mno-xsaves -mno-avx512dq -mno-avx512bw -mno-avx512vl -mno-avx512ifma -mno-avx512vbmi -mno-avx5124fmaps -mno-avx5124vnniw -mno-clwb -mno-mwaitx -mno-clzero -mno-pku -mno-rdpid --param "l1-cache-size=16" --param "l1-cache-line-size=64" --param "l2-cache-size=2048" "-mtune=bdver2"
  <...>

But clang does not: (look for `bdver1`)

  $ echo | clang -E - -march=native -###
  clang version 7.0.0- (trunk)
  Target: x86_64-pc-linux-gnu
  Thread model: posix
  InstalledDir: /usr/local/bin
   "/usr/lib/llvm-7/bin/clang" "-cc1" "-triple" "x86_64-pc-linux-gnu" "-E" "-disable-free" "-disable-llvm-verifier" "-discard-value-names" "-main-file-name" "-" "-mrelocation-model" "static" "-mthread-model" "posix" "-mdisable-fp-elim" "-fmath-errno" "-masm-verbose" "-mconstructor-aliases" "-munwind-tables" "-fuse-init-array" "-target-cpu" "bdver1" "-target-feature" "+sse2" "-target-feature" "+cx16" "-target-feature" "+sahf" "-target-feature" "+tbm" "-target-feature" "-avx512ifma" "-target-feature" "-sha" "-target-feature" "-gfni" "-target-feature" "+fma4" "-target-feature" "-vpclmulqdq" "-target-feature" "+prfchw" "-target-feature" "-bmi2" "-target-feature" "-cldemote" "-target-feature" "-fsgsbase" "-target-feature" "-xsavec" "-target-feature" "+popcnt" "-target-feature" "+aes" "-target-feature" "-avx512bitalg" "-target-feature" "-xsaves" "-target-feature" "-avx512er" "-target-feature" "-avx512vnni" "-target-feature" "-avx512vpopcntdq" "-target-feature" "-clwb" "-target-feature" "-avx512f" "-target-feature" "-clzero" "-target-feature" "-pku" "-target-feature" "+mmx" "-target-feature" "+lwp" "-target-feature" "-rdpid" "-target-feature" "+xop" "-target-feature" "-rdseed" "-target-feature" "-waitpkg" "-target-feature" "-ibt" "-target-feature" "+sse4a" "-target-feature" "-avx512bw" "-target-feature" "-clflushopt" "-target-feature" "+xsave" "-target-feature" "-avx512vbmi2" "-target-feature" "-avx512vl" "-target-feature" "-avx512cd" "-target-feature" "+avx" "-target-feature" "-vaes" "-target-feature" "-rtm" "-target-feature" "+fma" "-target-feature" "+bmi" "-target-feature" "-rdrnd" "-target-feature" "-mwaitx" "-target-feature" "+sse4.1" "-target-feature" "+sse4.2" "-target-feature" "-avx2" "-target-feature" "-wbnoinvd" "-target-feature" "+sse" "-target-feature" "+lzcnt" "-target-feature" "+pclmul" "-target-feature" "-prefetchwt1" "-target-feature" "+f16c" "-target-feature" "+ssse3" "-target-feature" "-sgx" "-target-feature" "-shstk" "-target-feature" "+cmov" "-target-feature" "-avx512vbmi" "-target-feature" "-movbe" "-target-feature" "-xsaveopt" "-target-feature" "-avx512dq" "-target-feature" "-adx" "-target-feature" "-avx512pf" "-target-feature" "+sse3" "-dwarf-column-info" "-debugger-tuning=gdb" "-resource-dir" "/usr/lib/llvm-7/lib/clang/7.0.0" "-internal-isystem" "/usr/local/include" "-internal-isystem" "/usr/lib/llvm-7/lib/clang/7.0.0/include" "-internal-externc-isystem" "/usr/include/x86_64-linux-gnu" "-internal-externc-isystem" "/include" "-internal-externc-isystem" "/usr/include" "-fdebug-compilation-dir" "/build/llvm-build-Clang-release" "-ferror-limit" "19" "-fmessage-length" "271" "-fobjc-runtime=gcc" "-fdiagnostics-show-option" "-fcolor-diagnostics" "-o" "-" "-x" "c" "-"

So clang, unlike gcc, considers this to be `bdver1`.

After some digging, i've come across `getAMDProcessorTypeAndSubtype()` in `Host.cpp`.
I have added the following debug printf after the call to that function in `sys::getHostCPUName()`:

  errs() << "Family " << Family << " Model " << Model << " Type " << Type "\n";

Which produced:

  Family 21 Model 2 Type 5

Which matches the `lscpu` output.

As it was pointed in the review by @craig.topper:

In https://reviews.llvm.org/D46314#1084123, @craig.topper wrote:

> I dont' think this is right. Here is what I found on wikipedia. https://en.wikipedia.org/wiki/List_of_AMD_CPU_microarchitectures.
>
> AMD Bulldozer Family 15h - the successor of 10h/K10. Bulldozer is designed for processors in the 10 to 220W category, implementing XOP, FMA4 and CVT16 instruction sets. Orochi was the first design which implemented it. For Bulldozer, CPUID model numbers are 00h and 01h.
>  AMD Piledriver Family 15h (2nd-gen) - successor to Bulldozer. CPUID model numbers are 02h (earliest "Vishera" Piledrivers) and 10h-1Fh.
>  AMD Steamroller Family 15h (3rd-gen) - third-generation Bulldozer derived core. CPUID model numbers are 30h-3Fh.
>  AMD Excavator Family 15h (4th-gen) - fourth-generation Bulldozer derived core. CPUID model numbers are 60h-6Fh, later updated revisions have model numbers 70h-7Fh.
>
> So there's a weird exception where model 2 should go with 0x10-0x1f.


Though It does not help that the code can't be tested at the moment.
With this logical change, the `bdver2` is properly detected.

  $ echo | /build/llvm-build-Clang-release/bin/clang -E - -march=native -###
  clang version 7.0.0 (trunk 331249) (llvm/trunk 331256)
  Target: x86_64-unknown-linux-gnu
  Thread model: posix
  InstalledDir: /build/llvm-build-Clang-release/bin
   "/build/llvm-build-Clang-release/bin/clang-7" "-cc1" "-triple" "x86_64-unknown-linux-gnu" "-E" "-disable-free" "-main-file-name" "-" "-mrelocation-model" "static" "-mthread-model" "posix" "-mdisable-fp-elim" "-fmath-errno" "-masm-verbose" "-mconstructor-aliases" "-munwind-tables" "-fuse-init-array" "-target-cpu" "bdver2" "-target-feature" "+sse2" "-target-feature" "+cx16" "-target-feature" "+sahf" "-target-feature" "+tbm" "-target-feature" "-avx512ifma" "-target-feature" "-sha" "-target-feature" "-gfni" "-target-feature" "+fma4" "-target-feature" "-vpclmulqdq" "-target-feature" "+prfchw" "-target-feature" "-bmi2" "-target-feature" "-cldemote" "-target-feature" "-fsgsbase" "-target-feature" "-xsavec" "-target-feature" "+popcnt" "-target-feature" "+aes" "-target-feature" "-avx512bitalg" "-target-feature" "-movdiri" "-target-feature" "-xsaves" "-target-feature" "-avx512er" "-target-feature" "-avx512vnni" "-target-feature" "-avx512vpopcntdq" "-target-feature" "-clwb" "-target-feature" "-avx512f" "-target-feature" "-clzero" "-target-feature" "-pku" "-target-feature" "+mmx" "-target-feature" "+lwp" "-target-feature" "-rdpid" "-target-feature" "+xop" "-target-feature" "-rdseed" "-target-feature" "-waitpkg" "-target-feature" "-movdir64b" "-target-feature" "-ibt" "-target-feature" "+sse4a" "-target-feature" "-avx512bw" "-target-feature" "-clflushopt" "-target-feature" "+xsave" "-target-feature" "-avx512vbmi2" "-target-feature" "-avx512vl" "-target-feature" "-avx512cd" "-target-feature" "+avx" "-target-feature" "-vaes" "-target-feature" "-rtm" "-target-feature" "+fma" "-target-feature" "+bmi" "-target-feature" "-rdrnd" "-target-feature" "-mwaitx" "-target-feature" "+sse4.1" "-target-feature" "+sse4.2" "-target-feature" "-avx2" "-target-feature" "-wbnoinvd" "-target-feature" "+sse" "-target-feature" "+lzcnt" "-target-feature" "+pclmul" "-target-feature" "-prefetchwt1" "-target-feature" "+f16c" "-target-feature" "+ssse3" "-target-feature" "-sgx" "-target-feature" "-shstk" "-target-feature" "+cmov" "-target-feature" "-avx512vbmi" "-target-feature" "-movbe" "-target-feature" "-xsaveopt" "-target-feature" "-avx512dq" "-target-feature" "-adx" "-target-feature" "-avx512pf" "-target-feature" "+sse3" "-dwarf-column-info" "-debugger-tuning=gdb" "-resource-dir" "/build/llvm-build-Clang-release/lib/clang/7.0.0" "-internal-isystem" "/usr/local/include" "-internal-isystem" "/build/llvm-build-Clang-release/lib/clang/7.0.0/include" "-internal-externc-isystem" "/usr/include/x86_64-linux-gnu" "-internal-externc-isystem" "/include" "-internal-externc-isystem" "/usr/include" "-fdebug-compilation-dir" "/build/llvm-build-Clang-release" "-ferror-limit" "19" "-fmessage-length" "271" "-fobjc-runtime=gcc" "-fdiagnostics-show-option" "-fcolor-diagnostics" "-o" "-" "-x" "c" "-"


Repository:
  rCRT Compiler Runtime

https://reviews.llvm.org/D46323

Files:
  lib/builtins/cpu_model.c


Index: lib/builtins/cpu_model.c
===================================================================
--- lib/builtins/cpu_model.c
+++ lib/builtins/cpu_model.c
@@ -416,7 +416,7 @@
       *Subtype = AMDFAM15H_BDVER3;
       break; // "bdver3"; 30h-3Fh: Steamroller
     }
-    if (Model >= 0x10 && Model <= 0x1f) {
+    if ((Model >= 0x10 && Model <= 0x1f) || Model == 0x02) {
       *Subtype = AMDFAM15H_BDVER2;
       break; // "bdver2"; 10h-1Fh: Piledriver
     }


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