Remove handling of AddrSpaceCast in stripAndAccumulateInBoundsConstantOffsets

Patch by: simoncook

Unlike BitCasts, AddrSpaceCasts do not always produce an output the same size as its input, which was previously assumed. This fixes cases where two address spaces do not have the same size pointer, as an assertion failure would occur when trying to prove deferenceability.  LoopUnswitch is used in the particular test, but LICM also exhibits the same problem.

Differential Revision: http://reviews.llvm.org/D13008

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@248422 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/IR/Value.cpp b/lib/IR/Value.cpp
index f554d590284fa895762527e7fa8eab569499e548..925f2058e5592f48dd06ce9cfeab7e9c48fbba15 100644 (file)
--- a/lib/IR/Value.cpp
+++ b/lib/IR/Value.cpp
@@ -490,8 +490,7 @@ Value *Value::stripAndAccumulateInBoundsConstantOffsets(const DataLayout &DL,
         return V;
       Offset = GEPOffset;
       V = GEP->getPointerOperand();
-    } else if (Operator::getOpcode(V) == Instruction::BitCast ||
-               Operator::getOpcode(V) == Instruction::AddrSpaceCast) {
+    } else if (Operator::getOpcode(V) == Instruction::BitCast) {
       V = cast<Operator>(V)->getOperand(0);
     } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
       V = GA->getAliasee();

diff --git a/test/Transforms/LoopUnswitch/2015-09-18-Addrspace.ll b/test/Transforms/LoopUnswitch/2015-09-18-Addrspace.ll
new file mode 100644 (file)
index 0000000..0f74614
--- /dev/null
+++ b/test/Transforms/LoopUnswitch/2015-09-18-Addrspace.ll
@@ -0,0 +1,28 @@
+; RUN: opt < %s -loop-unswitch -S | FileCheck %s
+
+; In cases where two address spaces do not have the same size pointer, the
+; input for the addrspacecast should not be used as a substitute for itself
+; when manipulating the pointer.
+
+target datalayout = "e-m:e-p:16:16-p1:32:16-i32:16-i64:16-n8:16"
+
+define void @foo() {
+; CHECK-LABEL: @foo
+entry:
+  %arrayidx.i1 = getelementptr inbounds i16, i16* undef, i16 undef
+  %arrayidx.i = addrspacecast i16* %arrayidx.i1 to i16 addrspace(1)*
+  br i1 undef, label %for.body.i, label %bar.exit
+
+for.body.i:                                       ; preds = %for.body.i, %entry
+; When we call makeLoopInvariant (i.e. trivial LICM) on this load, it 
+; will try to find the base object to prove deferenceability.  If we look
+; through the addrspacecast, we'll fail an assertion about bitwidths matching
+; CHECK-LABEL: for.body.i
+; CHECK:   %0 = load i16, i16 addrspace(1)* %arrayidx.i, align 2
+  %0 = load i16, i16 addrspace(1)* %arrayidx.i, align 2
+  %cmp1.i = icmp eq i16 %0, 0
+  br i1 %cmp1.i, label %bar.exit, label %for.body.i
+
+bar.exit:                                         ; preds = %for.body.i, %entry
+  ret void
+}