InstCombine: Don't assume DataLayout is always available

We tried to get the result of DataLayout::getLargestLegalIntTypeSize but
we didn't have a DataLayout.  This resulted in opt crashing.

This fixes PR21651.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222645 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/InstCombine/InstructionCombining.cpp b/lib/Transforms/InstCombine/InstructionCombining.cpp
index 292c20678ec6a9be05c6d30a256d034be90e4ec9..5eee15f648906cc4997e03a8aaf7ea002cf50063 100644 (file)
--- a/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -2095,7 +2095,8 @@ Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
   // the largest legal integer type. We need to be conservative here since
   // x86 generates redundant zero-extenstion instructions if the operand is
   // truncated to i8 or i16.
-  if (BitWidth > NewWidth && NewWidth >= DL->getLargestLegalIntTypeSize()) {
+  if (DL && BitWidth > NewWidth &&
+      NewWidth >= DL->getLargestLegalIntTypeSize()) {
     IntegerType *Ty = IntegerType::get(SI.getContext(), NewWidth);
     Builder->SetInsertPoint(&SI);
     Value *NewCond = Builder->CreateTrunc(SI.getCondition(), Ty, "trunc");

diff --git a/test/Transforms/InstCombine/pr21651.ll b/test/Transforms/InstCombine/pr21651.ll
new file mode 100644 (file)
index 0000000..914785f
--- /dev/null
+++ b/test/Transforms/InstCombine/pr21651.ll
@@ -0,0 +1,20 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+define void @PR21651() {
+  switch i2 0, label %out [
+    i2 0, label %out
+    i2 1, label %out
+  ]
+
+out:
+  ret void
+}
+
+; CHECK-LABEL: define void @PR21651(
+; CHECK:   switch i2 0, label %out [
+; CHECK:     i2 0, label %out
+; CHECK:     i2 1, label %out
+; CHECK:   ]
+; CHECK: out:                                              ; preds = %0, %0, %0
+; CHECK:   ret void
+; CHECK: }