fix PR10605 / rdar://9930964 by adding a pretty scary missed check.
It's somewhat surprising anything works without this. Before we would
compile the testcase into:
test: # @test
movl $4, 8(%rdi)
movl 8(%rdi), %eax
orl %esi, %eax
cmpl $32, %edx
movl %eax, -4(%rsp) # 4-byte Spill
je .LBB0_2
now we produce:
test: # @test
movl 8(%rdi), %eax
movl $4, 8(%rdi)
orl %esi, %eax
cmpl $32, %edx
movl %eax, -4(%rsp) # 4-byte Spill
je .LBB0_2
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@137303 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 87bb296..ec8f014 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -754,6 +754,11 @@
TheUser = TheUser->use_back();
}
+ // If we didn't find the fold instruction, then we failed to collapse the
+ // sequence.
+ if (TheUser != FoldInst)
+ return false;
+
// Don't try to fold volatile loads. Target has to deal with alignment
// constraints.
if (LI->isVolatile()) return false;