SROA: Don't create variable fragments that are outside of the variable.

An alloca may be larger than a variable that is described to be stored
there. Don't create a dbg.value for fragments that are outside of the
variable.

This fixes PR35447.
https://bugs.llvm.org/show_bug.cgi?id=35447

llvm-svn: 319230

1 files changed, 9 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Scalar/SROA.cpp b/llvm/lib/Transforms/Scalar/SROA.cpp
index b430d07406c..bd064978b64 100644
--- a/llvm/lib/Transforms/Scalar/SROA.cpp
+++ b/llvm/lib/Transforms/Scalar/SROA.cpp
@@ -4134,6 +4134,15 @@ bool SROA::splitAlloca(AllocaInst &AI, AllocaSlices &AS) {
                  "new fragment is outside of original fragment");
           Start -= OrigFragment->OffsetInBits;
         }
+
+        // The alloca may be larger than the variable.
+        if (VarSize) {
+          if (Size > *VarSize)
+            Size = *VarSize;
+          if (Size == 0 || Start + Size > *VarSize)
+            continue;
+        }
+
         // Avoid creating a fragment expression that covers the entire variable.
         if (!VarSize || *VarSize != Size) {
           if (auto E =