[PATCH] D83447: [X86] Directly emit X86ISD::BLENDV instead of VSELECT in a few places that were emitting sign bit tests.

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
craig.topper added reviewers: spatel, RKSimon.
Herald added a subscriber: hiraditya.
Herald added a project: LLVM.

Technically a VSELECT expects a vector of all 1s or 0s elements
for its condition.  But we aren't guaranteeing that the sign bit
and the non sign bits match in these locations. So we should use
BLENDV which is more relaxed.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D83447

Files:
  llvm/lib/Target/X86/X86ISelLowering.cpp


Index: llvm/lib/Target/X86/X86ISelLowering.cpp
===================================================================
--- llvm/lib/Target/X86/X86ISelLowering.cpp
+++ llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -27681,7 +27681,8 @@
         V0 = DAG.getBitcast(ExtVT, V0);
         V1 = DAG.getBitcast(ExtVT, V1);
         Sel = DAG.getBitcast(ExtVT, Sel);
-        return DAG.getBitcast(VT, DAG.getNode(X86ISD::BLENDV, dl, ExtVT, Sel, V0, V1));
+        return DAG.getBitcast(
+            VT, DAG.getNode(X86ISD::BLENDV, dl, ExtVT, Sel, V0, V1));
       }
       // On pre-SSE41 targets we splat the sign bit - a negative value will
       // set all bits of the lanes to true and VSELECT uses that in
@@ -27826,7 +27827,8 @@
         V0 = DAG.getBitcast(VT, V0);
         V1 = DAG.getBitcast(VT, V1);
         Sel = DAG.getBitcast(VT, Sel);
-        return DAG.getBitcast(SelVT, DAG.getNode(X86ISD::BLENDV, DL, VT, Sel, V0, V1));
+        return DAG.getBitcast(SelVT,
+                              DAG.getNode(X86ISD::BLENDV, DL, VT, Sel, V0, V1));
       }
       // On pre-SSE41 targets we test for the sign bit by comparing to
       // zero - a negative value will set all bits of the lanes to true


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