[PATCH] D64052: Return Undef from isBytewiseValue for empty arrays or structs

[Vitaly Buka via Phabricator via llvm-commits]

vitalybuka created this revision.
vitalybuka added reviewers: pcc, eugenis.
Herald added subscribers: llvm-commits, hiraditya.
Herald added a project: LLVM.
vitalybuka added a parent revision: D64031: isBytewiseValue checks ConstantVector element by element.

Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D64052

Files:
  llvm/lib/Analysis/ValueTracking.cpp
  llvm/unittests/Analysis/ValueTrackingTest.cpp


Index: llvm/unittests/Analysis/ValueTrackingTest.cpp
===================================================================
--- llvm/unittests/Analysis/ValueTrackingTest.cpp
+++ llvm/unittests/Analysis/ValueTrackingTest.cpp
@@ -798,7 +798,7 @@
         "i16* inttoptr (i96 -1 to i16*)",
     },
     {
-        "i8 0",
+        "i8 undef",
         "[0 x i8] zeroinitializer",
     },
     {
@@ -880,7 +880,7 @@
         "[2 x i16] [i16 -21836, i16 -21846]]",
     },
     {
-        "i8 0",
+        "i8 undef",
         "{ } zeroinitializer",
     },
     {
Index: llvm/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/lib/Analysis/ValueTracking.cpp
+++ llvm/lib/Analysis/ValueTracking.cpp
@@ -3179,6 +3179,13 @@
   if (isa<UndefValue>(V))
     return UndefInt8;
 
+  if (auto *T = dyn_cast<SequentialType>(V->getType()))
+    if (!T->getNumElements())
+      return UndefInt8;
+  if (auto *T = dyn_cast<StructType>(V->getType()))
+    if (!T->getNumElements())
+      return UndefInt8;
+
   Constant *C = dyn_cast<Constant>(V);
   if (!C) {
     // Conceptually, we could handle things like:


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