[PATCH] D59872: [X86MacroFusion] Handle branch fusion (AMD CPUs).

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added a comment.

Looks good.
Can there be a test that we don't fuse non-CMP/TEST instructions if we only have `branchfusion`?



================
Comment at: llvm/lib/Target/X86/X86.td:347-357
 // Sandy Bridge and newer processors have many instructions that can be
 // fused with conditional branches and pass through the CPU as a single
 // operation.
 def FeatureMacroFusion
     : SubtargetFeature<"macrofusion", "HasMacroFusion", "true",
                  "Various instructions can be fused with conditional branches">;
 
----------------
I think it would be better to swap these around?
`FeatureMacroFusion` is a superset of `FeatureBranchFusion`.
(maybe even inherit `FeatureBranchFusion` by `FeatureMacroFusion`, not sure it is possible here.)


================
Comment at: llvm/lib/Target/X86/X86.td:354
 
+// Bulldozer and newer processors can merge CMP/TEST with conditional branches.
+def FeatureBranchFusion
----------------
```
// Bulldozer and newer processors can merge CMP/TEST (but not other instructions)
// with conditional branches.
```


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D59872/new/

https://reviews.llvm.org/D59872