Merge commit d0be944aa511 from llvm-project (by Simon Pilgrim):

  [X86] Add slow div64 tuning flag to Nehalem target (#91129)

  This appears to have been missed because later cpus don't inherit from Nehalem tuning much.

  Noticed while cleaning up for #90985

Merge commit 8b400de79eff from llvm-project (by Simon Pilgrim):

  [X86] Enable TuningSlowDivide64 on Barcelona/Bobcat/Bulldozer/Ryzen Families (#91277)

  Despite most AMD cpus having a lower latency for i64 divisions that converge early, we are still better off testing for values representable as i32 and performing a i32 division if possible.

  All AMD cpus appear to have been missed when we added the "idivq-to-divl" attribute - this patch now matches Intel cpu behaviour (and the x86-64/v2/3/4 levels).

  Unfortunately the difference in code scheduling means I've had to stop using the update_llc_test_checks script and just use old-fashioned CHECK-DAG checks for divl/divq pairs.

  Fixes #90985

This fixes possibly worse runtime performance on AMD Zen hardware, when
using -march=znver4 (or any other znver), as opposed to -march=x86-64-v4
or the baseline -march=x86-64. A similar fix is applied for Nehalem.

PR:		278908
MFC after:	3 days

1 files changed, 6 insertions, 0 deletions

diff --git a/contrib/llvm-project/llvm/lib/Target/X86/X86.td b/contrib/llvm-project/llvm/lib/Target/X86/X86.td
index e89ddcc570c9..1aff5f9fad97 100644
--- a/contrib/llvm-project/llvm/lib/Target/X86/X86.td
+++ b/contrib/llvm-project/llvm/lib/Target/X86/X86.td
@@ -867,6 +867,7 @@ def ProcessorFeatures {
   // Nehalem
   list<SubtargetFeature> NHMFeatures = X86_64V2Features;
   list<SubtargetFeature> NHMTuning = [TuningMacroFusion,
+                                      TuningSlowDivide64,
                                       TuningInsertVZEROUPPER,
                                       TuningNoDomainDelayMov];
 
@@ -1336,6 +1337,7 @@ def ProcessorFeatures {
                                               FeatureCMOV,
                                               FeatureX86_64];
   list<SubtargetFeature> BarcelonaTuning = [TuningFastScalarShiftMasks,
+                                            TuningSlowDivide64,
                                             TuningSlowSHLD,
                                             TuningSBBDepBreaking,
                                             TuningInsertVZEROUPPER];
@@ -1358,6 +1360,7 @@ def ProcessorFeatures {
   list<SubtargetFeature> BtVer1Tuning = [TuningFast15ByteNOP,
                                          TuningFastScalarShiftMasks,
                                          TuningFastVectorShiftMasks,
+                                         TuningSlowDivide64,
                                          TuningSlowSHLD,
                                          TuningSBBDepBreaking,
                                          TuningInsertVZEROUPPER];
@@ -1380,6 +1383,7 @@ def ProcessorFeatures {
                                          TuningFastVectorShiftMasks,
                                          TuningFastMOVBE,
                                          TuningSBBDepBreaking,
+                                         TuningSlowDivide64,
                                          TuningSlowSHLD];
   list<SubtargetFeature> BtVer2Features =
     !listconcat(BtVer1Features, BtVer2AdditionalFeatures);
@@ -1404,6 +1408,7 @@ def ProcessorFeatures {
                                            FeatureLWP,
                                            FeatureLAHFSAHF64];
   list<SubtargetFeature> BdVer1Tuning = [TuningSlowSHLD,
+                                         TuningSlowDivide64,
                                          TuningFast11ByteNOP,
                                          TuningFastScalarShiftMasks,
                                          TuningBranchFusion,
@@ -1483,6 +1488,7 @@ def ProcessorFeatures {
                                      TuningFastScalarShiftMasks,
                                      TuningFastVariablePerLaneShuffle,
                                      TuningFastMOVBE,
+                                     TuningSlowDivide64,
                                      TuningSlowSHLD,
                                      TuningSBBDepBreaking,
                                      TuningInsertVZEROUPPER,