[SDAG] Remove noundef workaround for range metadata/attributes (#141745)

In https://reviews.llvm.org/D157685 I changed SDAG to only transfer
range metadata to SDAG if it also has !noundef. At the time, this was
necessary because SDAG incorrectly propagated poison when folding
logical and/or to bitwise and/or.

The root cause of that issue has since been addressed by
https://github.com/llvm/llvm-project/pull/84924, so drop the workaround
now.

1 files changed, 3 insertions, 13 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 693a7f5..77771ee 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -4468,23 +4468,13 @@ void SelectionDAGBuilder::visitAlloca(const AllocaInst &I) {
 }
 
 static const MDNode *getRangeMetadata(const Instruction &I) {
-  // If !noundef is not present, then !range violation results in a poison
-  // value rather than immediate undefined behavior. In theory, transferring
-  // these annotations to SDAG is fine, but in practice there are key SDAG
-  // transforms that are known not to be poison-safe, such as folding logical
-  // and/or to bitwise and/or. For now, only transfer !range if !noundef is
-  // also present.
-  if (!I.hasMetadata(LLVMContext::MD_noundef))
-    return nullptr;
   return I.getMetadata(LLVMContext::MD_range);
 }
 
 static std::optional<ConstantRange> getRange(const Instruction &I) {
-  if (const auto *CB = dyn_cast<CallBase>(&I)) {
-    // see comment in getRangeMetadata about this check
-    if (CB->hasRetAttr(Attribute::NoUndef))
-      return CB->getRange();
-  }
+  if (const auto *CB = dyn_cast<CallBase>(&I))
+    if (std::optional<ConstantRange> CR = CB->getRange())
+      return CR;
   if (const MDNode *Range = getRangeMetadata(I))
     return getConstantRangeFromMetadata(*Range);
   return std::nullopt;