[PATCH] D94433: [ValueTracking] Check that alignment is non-zero in computeKnownBitsFromAssume (PR48713).

[Ryan Mansfield via Phabricator via llvm-commits]

rmansfield created this revision.
rmansfield added a reviewer: spatel.
Herald added a subscriber: hiraditya.
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Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D94433

Files:
  llvm/lib/Analysis/ValueTracking.cpp
  llvm/test/Analysis/ValueTracking/pr48713.ll


Index: llvm/test/Analysis/ValueTracking/pr48713.ll
===================================================================
--- /dev/null
+++ llvm/test/Analysis/ValueTracking/pr48713.ll
@@ -0,0 +1,11 @@
+; RUN: opt -instsimplify < %s
+
+define i8* @PR48713() {
+  %call = call i8* @PR48713()
+  call void @llvm.assume(i1 true) [ "align"(i8* %call, i64 0) ]
+  %cmp = icmp eq i8* %call, null
+  %conv = zext i1 %cmp to i32
+  ret i8* null
+}
+
+declare void @llvm.assume(i1 noundef)
Index: llvm/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/lib/Analysis/ValueTracking.cpp
+++ llvm/lib/Analysis/ValueTracking.cpp
@@ -666,7 +666,8 @@
   if (V->getType()->isPointerTy()) {
     if (RetainedKnowledge RK = getKnowledgeValidInContext(
             V, {Attribute::Alignment}, Q.CxtI, Q.DT, Q.AC)) {
-      Known.Zero.setLowBits(Log2_32(RK.ArgValue));
+      if (RK.ArgValue)
+        Known.Zero.setLowBits(Log2_32(RK.ArgValue));
     }
   }
 


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