[SROA] pr37267: fix assertion failure in integer widening

The current integer widening does not support rewriting partial split slices in rewriteIntegerStore (and rewriteIntegerLoad).
This patch adds explicit checks for this case in isIntegerWideningViableForSlice.
Before r322533, splitting is allowed only for the whole-alloca slice and hence the above case is implicitly rejected by another check `if (DL.getTypeStoreSize(ValueTy) > Size)` because whole-alloca slice is larger than the partition.

Differential Revision: https://reviews.llvm.org/D46750

llvm-svn: 332575

1 files changed, 8 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Scalar/SROA.cpp b/llvm/lib/Transforms/Scalar/SROA.cpp
index 2db08b72972..7c2fb4b788d 100644
--- a/llvm/lib/Transforms/Scalar/SROA.cpp
+++ b/llvm/lib/Transforms/Scalar/SROA.cpp
@@ -1968,6 +1968,10 @@ static bool isIntegerWideningViableForSlice(const Slice &S,
     // We can't handle loads that extend past the allocated memory.
     if (DL.getTypeStoreSize(LI->getType()) > Size)
       return false;
+    // So far, AllocaSliceRewriter does not support widening split slice tails
+    // in rewriteIntegerLoad.
+    if (S.beginOffset() < AllocBeginOffset)
+      return false;
     // Note that we don't count vector loads or stores as whole-alloca
     // operations which enable integer widening because we would prefer to use
     // vector widening instead.
@@ -1989,6 +1993,10 @@ static bool isIntegerWideningViableForSlice(const Slice &S,
     // We can't handle stores that extend past the allocated memory.
     if (DL.getTypeStoreSize(ValueTy) > Size)
       return false;
+    // So far, AllocaSliceRewriter does not support widening split slice tails
+    // in rewriteIntegerStore.
+    if (S.beginOffset() < AllocBeginOffset)
+      return false;
     // Note that we don't count vector loads or stores as whole-alloca
     // operations which enable integer widening because we would prefer to use
     // vector widening instead.