[PATCH] D93292: [AArch64][SVE] Add optimization to remove redundant ptest instructions

[Paul Walker via Phabricator via llvm-commits]

paulwalker-arm added a comment.

Other than some missing tests this looks reasonable to me.



================
Comment at: llvm/lib/Target/AArch64/AArch64InstrInfo.cpp:1341-1365
+    switch (Pred->getOpcode()) {
+    case AArch64::BRKB_PPzP:
+    case AArch64::BRKPB_PPzPP: {
+      // Op 0 is chain, 1 is the mask, 2 the previous predicate to
+      // propagate, 3 the new predicate.
+
+      // Check to see if our mask is the same as the brkpb's. If
----------------
I cannot see any unit tests for this block of functionality.


================
Comment at: llvm/lib/Target/AArch64/AArch64InstrInfo.cpp:1394-1395
+
+  // If we've gotten past all the checks, it's safe to remove the ptest
+  // and use the flag-setting form of brkpb.
+  Pred->setDesc(get(NewOp));
----------------
What about:

If we pass all the checks, it's safe to remove the PTEST and either use the flags as they are prior to PTEST.  Sometimes this requires the tested PTEST operand to be replaced with an equivalent instruction that also sets the flags.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D93292/new/

https://reviews.llvm.org/D93292