[PATCH] D112618: [BasicAA] Remove misleading overflow check

[Nikita Popov via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rG665060ea4583: [BasicAA] Remove misleading overflow check (authored by nikic).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D112618/new/

https://reviews.llvm.org/D112618

Files:
  llvm/lib/Analysis/BasicAliasAnalysis.cpp


Index: llvm/lib/Analysis/BasicAliasAnalysis.cpp
===================================================================
--- llvm/lib/Analysis/BasicAliasAnalysis.cpp
+++ llvm/lib/Analysis/BasicAliasAnalysis.cpp
@@ -657,23 +657,8 @@
 
       // The GEP index scale ("Scale") scales C1*V+C2, yielding (C1*V+C2)*Scale.
       // This gives us an aggregate computation of (C1*Scale)*V + C2*Scale.
-
-      // It can be the case that, even through C1*V+C2 does not overflow for
-      // relevant values of V, (C2*Scale) can overflow. In that case, we cannot
-      // decompose the expression in this way.
-      //
-      // FIXME: C1*Scale and the other operations in the decomposed
-      // (C1*Scale)*V+C2*Scale can also overflow. We should check for this
-      // possibility.
-      bool Overflow;
-      APInt ScaledOffset = LE.Offset.sextOrTrunc(MaxPointerSize)
-                           .smul_ov(Scale, Overflow);
-      if (Overflow) {
-        LE = LinearExpression(CastedValue(Index, 0, SExtBits, TruncBits));
-      } else {
-        Decomposed.Offset += ScaledOffset;
-        Scale *= LE.Scale.sextOrTrunc(MaxPointerSize);
-      }
+      Decomposed.Offset += LE.Offset.sextOrTrunc(MaxPointerSize) * Scale;
+      Scale *= LE.Scale.sextOrTrunc(MaxPointerSize);
 
       // If we already had an occurrence of this index variable, merge this
       // scale into it.  For example, we want to handle:


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