[PATCH] D90710: [UBSan] Cannot negate smallest negative signed integer

[Christopher Tetreault via Phabricator via llvm-commits]

ctetreau created this revision.
Herald added subscribers: llvm-commits, hiraditya.
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Silence warning Undefined Behavior Sanitzer warning:
runtime error: negation of -9223372036854775808 cannot be represented in type 'int64_t' (aka 'long'); cast to an unsigned type to negate this value to itself


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D90710

Files:
  llvm/lib/Target/AArch64/AArch64ISelLowering.cpp


Index: llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
===================================================================
--- llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -6228,7 +6228,8 @@
       // instead of a CSEL in that case.
       if (TrueVal == ~FalseVal) {
         Opcode = AArch64ISD::CSINV;
-      } else if (TrueVal == -FalseVal) {
+      } else if (FalseVal > std::numeric_limits<int64_t>::min() &&
+                 TrueVal == -FalseVal) {
         Opcode = AArch64ISD::CSNEG;
       } else if (TVal.getValueType() == MVT::i32) {
         // If our operands are only 32-bit wide, make sure we use 32-bit


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