[PATCH] D110437: [IR] Handle large element size when calculating GEP indices

[Nikita Popov via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rG5969e5743ae9: [IR] Handle large element size when calculating GEP indices (authored by nikic).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D110437/new/

https://reviews.llvm.org/D110437

Files:
  llvm/lib/IR/DataLayout.cpp
  llvm/test/Transforms/GlobalOpt/large-element-size.ll


Index: llvm/test/Transforms/GlobalOpt/large-element-size.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/GlobalOpt/large-element-size.ll
@@ -0,0 +1,12 @@
+; RUN: opt -S -passes=globalopt < %s | FileCheck %s
+
+target datalayout = "p:32:32"
+
+%struct.s.2 = type { %struct.t.1, %struct.t.1, %struct.t.1, %struct.u.0, %struct.u.0 }
+%struct.t.1 = type { %struct.u.0, %struct.u.0, %struct.u.0, %struct.u.0, i32, i32, i32, i32 }
+%struct.u.0 = type { i32, i32, i32, i8 }
+
+ at s = external global [700 x [24000 x %struct.s.2]], align 1
+ at p = global %struct.s.2* bitcast (i8* getelementptr (i8, i8* bitcast ([700 x [24000 x %struct.s.2]]* @s to i8*), i64 2247483647) to %struct.s.2*), align 1
+
+; CHECK: @p = local_unnamed_addr global %struct.s.2* bitcast (i8* getelementptr (i8, i8* bitcast ([700 x [24000 x %struct.s.2]]* @s to i8*), i32 -2047483649) to %struct.s.2*), align 1
Index: llvm/lib/IR/DataLayout.cpp
===================================================================
--- llvm/lib/IR/DataLayout.cpp
+++ llvm/lib/IR/DataLayout.cpp
@@ -903,9 +903,13 @@
 
 static void addElementIndex(SmallVectorImpl<APInt> &Indices, TypeSize ElemSize,
                             APInt &Offset) {
-  // Skip over scalable or zero size elements.
-  if (ElemSize.isScalable() || ElemSize == 0) {
-    Indices.push_back(APInt::getZero(Offset.getBitWidth()));
+  // Skip over scalable or zero size elements. Also skip element sizes larger
+  // than the positive index space, because the arithmetic below may not be
+  // correct in that case.
+  unsigned BitWidth = Offset.getBitWidth();
+  if (ElemSize.isScalable() || ElemSize == 0 ||
+      !isUIntN(BitWidth - 1, ElemSize)) {
+    Indices.push_back(APInt::getZero(BitWidth));
     return;
   }
 


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