commit 59a4ee97288b1297bb98edd7f24fecd5e9c57170
author Amara Emerson <amara@apple.com> Wed May 26 23:28:44 2021 -0700
committer Amara Emerson <amara@apple.com> Thu May 27 23:52:24 2021 -0700
tree 54b37a786608e6cdb260db4dc97bc2aa0bf64016
parent 6a2af607ad3523ddc3778b0efb7bb1d5d42a1edb

[AArch64][GlobalISel] Legalize oversize G_EXTRACT_VECTOR_ELT sources.

Also changes the fewerElements helper to use the lookthrough constant helper
instead of m_ICst, since m_ICst doesn't look through extends.

Differential Revision: https://reviews.llvm.org/D103227

llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp

diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index 8dca8bf..4240f7f 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -3807,7 +3807,11 @@
   // If the index is a constant, we can really break this down as you would
   // expect, and index into the target size pieces.
   int64_t IdxVal;
-  if (mi_match(Idx, MRI, m_ICst(IdxVal))) {
+  auto MaybeCst =
+      getConstantVRegValWithLookThrough(Idx, MRI, /*LookThroughInstrs*/ true,
+                                        /*HandleFConstants*/ false);
+  if (MaybeCst) {
+    IdxVal = MaybeCst->Value.getSExtValue();
     // Avoid out of bounds indexing the pieces.
     if (IdxVal >= VecTy.getNumElements()) {
       MIRBuilder.buildUndef(DstReg);