[X86] Add a common-avx512 CPU to match icc's -xCOMMON-AVX512 option

[craig.topper]

Summary

This adds a common-avx512 CPU to target the avx512 features common between skylake-avx512 and knl.

[greened]

include/llvm/Support/X86TargetParser.def

70

Is there any reason in particular this isn't grouped with the other INTEL declarations above? I don't know if it should be or not. I assume eventually AMD will have an AVX512 offering and maybe common-avx512 can be used for both Intel and AMD targets.

lib/Target/X86/X86.td

874

AVX512F is supposed to be the minimum support needed for common AVX512 functionality. Instead of "common" throughout, would it make sense to just say "avx512f?" "common-avx512" isn't a specification that exists anywhere, while "avx512f" is.

[craig.topper]

lib/Target/X86/X86.td

874

This also includes AVX512CD(strangely named FeatureCDI) which both KNL and skylake support and is enabled by the -xCOMMON-AVX512 option in icc. I'm just trying to match that existing feature. I'll admit the name sucks

[greened]

lib/Target/X86/X86.td

874

Ok, thanks for explaining. What about "avx512f-cd?" That name sucks too but is at least descriptive of what this is. "Common" seems too generic to me.

[craig.topper]

Abandoning after an internal discussion

include/llvm/Support/X86TargetParser.def

 X86_CPU_TYPE                  ("nocona",      INTEL_NOCONA)
 X86_CPU_TYPE                  ("prescott",    INTEL_PRESCOTT)
 X86_CPU_TYPE                  ("i486",        AMD_i486)
 X86_CPU_TYPE                  ("pentium",     AMDPENTIUM)
 X86_CPU_TYPE                  ("athlon",      AMD_ATHLON)
 X86_CPU_TYPE                  ("athlon-xp",   AMD_ATHLON_XP)
 X86_CPU_TYPE                  ("k8",          AMD_K8)
 X86_CPU_TYPE                  ("k8-sse3",     AMD_K8SSE3)
+X86_CPU_TYPE                  ("common-avx512", INTEL_COMMON_AVX512)
 #undef X86_CPU_TYPE_COMPAT_WITH_ALIAS
 #undef X86_CPU_TYPE_COMPAT
 #undef X86_CPU_TYPE
 
 // This macro is used for cpu subtypes present in compiler-rt/libgcc.
 #ifndef X86_CPU_SUBTYPE_COMPAT
 #define X86_CPU_SUBTYPE_COMPAT(ARCHNAME, ENUM, STR) X86_CPU_SUBTYPE(ARCHNAME, ENUM)
 #endif

lib/Target/X86/X86.td

 class SkylakeServerProc<string Name> : ProcModel<Name, SkylakeServerModel,
                                                  SKXFeatures.Value, [
   FeatureHasFastGather,
   FeaturePOPCNTFalseDeps
 ]>;
 def : SkylakeServerProc<"skylake-avx512">;
 def : SkylakeServerProc<"skx">; // Legacy alias.
 
+// Fake CPU to represent the intersection between SKX and KNL. Matches
+// icc's -xCOMMON-AVX512. BDW ISA + AVX512F + AVX512CD.
+class CommonAVX512Proc<string Name> : ProcModel<Name, BroadwellModel,
+                                                BDWFeatures.Value, [
+  FeatureAVX512,
+  FeatureCDI,
+  FeaturePOPCNTFalseDeps,
+  FeatureLZCNTFalseDeps
+]>;
+def : CommonAVX512Proc<"common-avx512">;
+
 def CNLFeatures : ProcessorFeatures<SKLFeatures.Value, [
   FeatureAVX512,
   FeatureCDI,
   FeatureDQI,
   FeatureBWI,
   FeatureVLX,
   FeaturePKU,
   FeatureVBMI,

test/CodeGen/X86/cpus-intel.ll

 ; RUN: llc < %s -o /dev/null -mtriple=x86_64-unknown-unknown -mcpu=bonnell 2>&1 | FileCheck %s --check-prefix=CHECK-NO-ERROR --allow-empty
 ; RUN: llc < %s -o /dev/null -mtriple=x86_64-unknown-unknown -mcpu=silvermont 2>&1 | FileCheck %s --check-prefix=CHECK-NO-ERROR --allow-empty
 ; RUN: llc < %s -o /dev/null -mtriple=x86_64-unknown-unknown -mcpu=slm 2>&1 | FileCheck %s --check-prefix=CHECK-NO-ERROR --allow-empty
 ; RUN: llc < %s -o /dev/null -mtriple=x86_64-unknown-unknown -mcpu=goldmont 2>&1 | FileCheck %s --check-prefix=CHECK-NO-ERROR --allow-empty
 ; RUN: llc < %s -o /dev/null -mtriple=x86_64-unknown-unknown -mcpu=goldmont-plus 2>&1 | FileCheck %s --check-prefix=CHECK-NO-ERROR --allow-empty
 ; RUN: llc < %s -o /dev/null -mtriple=x86_64-unknown-unknown -mcpu=tremont 2>&1 | FileCheck %s --check-prefix=CHECK-NO-ERROR --allow-empty
 ; RUN: llc < %s -o /dev/null -mtriple=x86_64-unknown-unknown -mcpu=knl 2>&1 | FileCheck %s --check-prefix=CHECK-NO-ERROR --allow-empty
 ; RUN: llc < %s -o /dev/null -mtriple=x86_64-unknown-unknown -mcpu=knm 2>&1 | FileCheck %s --check-prefix=CHECK-NO-ERROR --allow-empty
+; RUN: llc < %s -o /dev/null -mtriple=x86_64-unknown-unknown -mcpu=common-avx512 2>&1 | FileCheck %s --check-prefix=CHECK-NO-ERROR --allow-empty
 
 define void @foo() {
   ret void
 }