[PATCH] D106257: [ISD] Add disclaimer comments to AssertSext/Zext/Align opcodes about poison values

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon created this revision.
RKSimon added reviewers: eli.friedman, aqjune, spatel, craig.topper, xiangzhangllvm, LuoYuanke.
RKSimon requested review of this revision.
Herald added a project: LLVM.

As encountered on D106053 <https://reviews.llvm.org/D106053>, we need to be very explicit that the Assertion nodes don't hold true for a poison value (or for specific poisoned vector elements).


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D106257

Files:
  llvm/include/llvm/CodeGen/ISDOpcodes.h


Index: llvm/include/llvm/CodeGen/ISDOpcodes.h
===================================================================
--- llvm/include/llvm/CodeGen/ISDOpcodes.h
+++ llvm/include/llvm/CodeGen/ISDOpcodes.h
@@ -55,9 +55,16 @@
   /// value that has already been zero or sign extended from a narrower type.
   /// These nodes take two operands.  The first is the node that has already
   /// been extended, and the second is a value type node indicating the width
-  /// of the extension
+  /// of the extension.
+  /// NOTE: In case of the source value (or any vector element value) is
+  /// poisoned the assertion will not be true for that value.
   AssertSext,
   AssertZext,
+
+  /// AssertAlign - These nodes record if a register contains a value that
+  /// has a known alignment and the trailing bits are known to be zero.
+  /// NOTE: In case of the source value (or any vector element value) is
+  /// poisoned the assertion will not be true for that value.
   AssertAlign,
 
   /// Various leaf nodes.


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