[PATCH] D25849: [GVN] Prevent load coercion with irregular vector types

[Davide Italiano via llvm-commits]

davide updated this revision to Diff 75379.
davide added a comment.

Yes, it's alignTo (didn't look at MathExtras.h before this commit, sorry =)). Reordered the check. Does it look OK to you?
BTW, RKSimon gave LGTM offline (forgot to mention).


https://reviews.llvm.org/D25849

Files:
  lib/Transforms/Scalar/GVN.cpp
  test/Transforms/GVN/i7vector.ll


Index: test/Transforms/GVN/i7vector.ll
===================================================================
--- /dev/null
+++ test/Transforms/GVN/i7vector.ll
@@ -0,0 +1,16 @@
+; RUN: opt -gvn %s -S -o -
+
+define void @f() {
+entry:
+  %a = alloca <7 x i1>, align 2
+  store <7 x i1> undef, <7 x i1>* %a, align 2
+  %0 = getelementptr inbounds <7 x i1>, <7 x i1>* %a, i64 0, i64 0
+  %val = load i1, i1* %0, align 2
+  br i1 %val, label %cond.true, label %cond.false
+
+cond.true:
+  ret void
+
+cond.false:
+  ret void
+}
Index: lib/Transforms/Scalar/GVN.cpp
===================================================================
--- lib/Transforms/Scalar/GVN.cpp
+++ lib/Transforms/Scalar/GVN.cpp
@@ -713,9 +713,16 @@
       StoredVal->getType()->isArrayTy())
     return false;
 
+  uint64_t StoreSize = DL.getTypeSizeInBits(StoredVal->getType());
+
+  // Prevent load coercion with irregular vector types (e.g. <7 x i1>).
+  // Other parts of the code don't deal with them very well and we're
+  // going to crash later anyway.
+  if (llvm::alignTo(StoreSize, 8) != StoreSize)
+    return false;
+
   // The store has to be at least as big as the load.
-  if (DL.getTypeSizeInBits(StoredVal->getType()) <
-        DL.getTypeSizeInBits(LoadTy))
+  if (StoreSize < DL.getTypeSizeInBits(LoadTy))
     return false;
 
   return true;


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